Introduction
This Glossary was compiled to promote a common understanding
of the terms used in the Air Traffic Control system. It includes those
terms which are intended for pilot/controller communications. Those terms
most frequently used in pilot/controller communications are printed in
bold italics. The definitions are primarily defined in an operational sense
applicable to both users and operators of the National Airspace System.
Use of the Glossary will preclude any misunderstandings concerning the
system's design, function, and purpose.
Because of the international nature of flying, terms used in
the Lexicon, published by the International Civil Aviation Organization
(ICAO), are included when they differ from FAA definitions. These terms
are italicized {Note: In this electronic text these terms are prefaced
by "[ICAO]" - Ed.} For the reader's convenience, there are also cross-references
to related terms in other parts of the Glossary and to other documents,
such as the Federal Aviation Regulations (FARs) and the Aeronautical Information
Manual (AIM).
This Glossary will be revised, as necessary, to maintain a common
understanding of the system.
A
AAI - (See Arrival Aircraft Interval)
AAR - (See Airport Acceptance Rate)
Abbreviated IFR Flight Plans -
An authorization by ATC requiring pilots to submit only that
information needed for the purpose of ATC. It includes only a small portion
of the usual IFR flight plan information. In certain instances, this may
be only aircraft identification, locations, and pilot request. Other information
may be requested if needed by ATC for separation/control purposes. It is
frequently used by aircraft which are airborne and desire an instrument
approach or by aircraft which are on the ground and desire a climb to VFR
on top. (See VFR on top) (Refer to AIM)
ABEAM -
An aircraft is "abeam" a fix, point, or object when that fix,
point, or object is approximately 90 degrees to the right or left of the
aircraft track. Abeam indicates a general position rather than a precise
point.
ABORT -
To terminate a preplanned aircraft maneuver; e.g., an aborted
takeoff.
[ICAO] ACC - (See Area Control Center)
Accelerate-Stop Distance Available (ASDA) -
The runway plus stopway length declared available and suitable
for the acceleration and deceleration of an airplane aborting a takeoff.
[ICAO] Accelerate-Stop Distance Available (ASDA) -
The length of the takeoff run available plus the length of the
stopway if provided.
ACDO - (See Air Carrier District Office)
ACKNOWLEDGE -
Let me know that you have received my message. (See [ICAO] Acknowledge).
[ICAO] Acknowledge -
Let me know that you have received and understood this message.
ACLS - (See Automatic Carrier Landing System)
ACLT - (See Actual Calculated Landing Time (ACLT))
Acrobatic Flight -
An intentional maneuver involving an abrupt change in an aircraft's
attitude, an abnormal attitude, or abnormal acceleration not necessary
for normal flight. (Refer to FAR Part 91) (See [ICAO] Acrobatic Flight)
[ICAO] Acrobatic Flight -
Maneuvers intentionally performed by an aircraft involving an
abrupt change in its attitude, an abnormal attitude, or an abnormal variation
in speed.
Active Runway - (See Runway In Use/Active Runway/Duty Runway)
Actual Calculated Landing Time (ACLT) -
ACLT is a flight's frozen calculated landing time. An actual
time determined at freeze calculated landing time (FCLT) or meter list
display interval (MLDI) for the adapted vertex for each arrival aircraft
based upon runway configuration, airport acceptance rate, airport arrival
delay period, and other metered arrival aircraft. This time is either the
vertex time of arrival (VTA) of the aircraft or the tentative calculated
landing time (TCLT)/ACLT of the previous aircraft plus the arrival aircraft
interval (AAI), whichever is later. This time will not be updated in response
to the aircraft's progress.
Additional Services -
Advisory information provided by ATC which includes but is not
limited to the following:
1. Traffic advisories.
2. Vectors, when requested by the pilot, to assist aircraft
receiving traffic advisories to avoid observed traffic.
3. Altitude deviation information of 300 feet or more from an
assigned altitude as observed on a verified (reading correctly) automatic
altitude readout (Mode C).
4. Advisories that traffic is no longer a factor.
5. Weather and chaff information.
6. Weather assistance.
7. Bird activity information.
8. Holding pattern surveillance.
Additional services are provided to the extent possible contingent
only upon the controller's capability to fit them into the performance
of higher priority duties and on the basis of limitations of the radar,
volume of traffic, frequency congestions, and controller workload. The
controller has complete discretion for determining if he is able to provide
or continue to provide a service in a particular case. The controller's
reason not to provide or continue to provide a service in a particular
case is not subject to question by the pilot and need not be made known
to him. (See Traffic Advisories) (Refer to AIM)
ADF - (See Automatic Direction Finder)
ADIZ - (See Air Defense Identification Zone)
ADLY - (See Arrival Delay))
{New-98-3 Revised February 26, 1998}
Administrator -
The Federal Aviation Administrator or any person to whom he/she
has delegated his/her authority in the matter concerned.
ADVISE INTENTIONS -
Tell me what you plan to do.
Advisory -
Advice and information provided to assist pilots in the safe
conduct of flight and aircraft movement. (See Advisory Service)
Advisory Frequency -
The appropriate frequency to be used for Airport Advisory Service.
(See Local Airport Advisory, UNICOM). Refer to Advisory Circular No. 90-42
and AIM)
Advisory Service -
Advice and information provided by a facility to assist pilots
in the safe conduct of flight and aircraft movement. (See Local Airport
Advisory, Traffic Advisories, Safety Alert, Additional Services, Radar
Advisory, Enroute Flight Advisory Service) (Refer to AIM)
Aerial Refueling -
A procedure used by the military to transfer fuel from one aircraft
to another during flight. (Refer to VFR/IFR Wall Planning Charts).
Aerodrome -
A defined area on land or water (including any buildings, installations
and equipment) intended to be used either wholly or in part for the arrival,
departure, and movement of aircraft.
[ICAO] Aerodrome Beacon -
Aeronautical beacon used to indicate the location of an aerodrome
from the air.
[ICAO] Aerodrome Control Service -
Air traffic control service for aerodrome traffic.
[ICAO] Aerodrome Control Tower -
A unit established to provide air traffic control service to
aerodrome traffic.
[ICAO] Aerodrome Elevation -
The elevation of the highest point of the landing area.
[ICAO] Aerodrome Traffic Circuit -
The specified path to be flown by aircraft operating in the vicinity
of an aerodrome.
Aeronautical Beacon -
A visual NAVAID displaying flashes of white and/or colored light
to indicate the location of an airport, a heliport, a landmark, a certain
point of a Federal airway in mountainous terrain, or an obstruction. (See
Airport Rotating Beacon) (Refer to AIM)
Aeronautical Chart -
A map used in air navigation containing all or part of the following:
Topographic features, hazards and obstructions, navigation aids, navigation
routes, designated airspace, and airports. Commonly used aeronautical charts
are:
a. Sectional Charts (1:500,000) - Designed for visual navigation
of slow or medium speed aircraft. Topographic information on these charts
features the portrayal of relief and a judicious selection of visual check
points for VFR flight. Aeronautical information includes visual and radio
aids to navigation, airports, controlled airspace, restricted areas, obstructions,
and related data.
b. VFR Terminal Area Charts (1:250,000) - Depict Class B airspace
which provides for the control or segregation of all the aircraft within
Class B airspace. The chart depicts topographic information and aeronautical
information which includes visual and radio aids to navigation, airports,
controlled airspace, restricted areas, obstructions, and related data.
c. World Aeronautical Charts (WAC) (1:1,000,000) - Provide a
standard series of aeronautical charts, covering land areas of the world
at a size and scale convenient for navigation by moderate speed aircraft.
Topographic information includes cities and towns, principal roads, railroads,
distinctive landmarks, drainage, and relief. Aeronautical information includes
visual and radio aids to navigation, airports, airways, restricted areas,
obstructions, and other pertinent data.
d. Enroute Low Altitude Charts - Provide aeronautical information
for enroute instrument navigation (IFR) in the low altitude stratum. Information
includes the portrayal of airways, limits of controlled airspace, position
identification and frequencies of radio aids, selected airports, minimum
enroute and minimum obstruction clearance altitudes, airway distances,
reporting points, restricted areas, and related data. Area charts, which
are a part of this series, furnish terminal data at a larger scale in congested
areas.
e. Enroute High Altitude Charts - Provide aeronautical information
for enroute instrument navigation (IFR) in the high altitude stratum. Information
includes the portrayal of jet routes, identification and frequencies of
radio aids, selected airports, distances, time zones, special use airspace,
and related information.
f. Instrument Approach Procedures (IAP) Charts - Portray the
aeronautical data which is required to execute an instrument approach to
an airport. These charts depict the procedures, including all related data,
and the airport diagram. Each procedure is designated for use with a specific
type of electronic navigation system including NDB, TACAN, VOR, ILS/MLS,
and RNAV. These charts are identified by the type of navigational aid(s)
which provide final approach guidance.
{New-98-8 Revised August 13, 1998. "DP" was "SID"}
g. Instrument Departure Procedure (DP) Charts - Designed to
expedite clearance delivery and to facilitate transition between takeoff
and enroute operations. Each DP is presented as a separate chart and may
serve a single airport or more than one airport in a given geographical
location.
h. Standard Terminal Arrival (STAR) Charts - Designed to expedite
air traffic control arrival procedures and to facilitate transition between
enroute and instrument approach operations. Each STAR procedure is presented
as a separate chart and may serve a single airport or more than one airport
in a given geographical location.
i. Airport Taxi Charts - Designed to expedite the efficient
and safe flow of ground traffic at an airport. These charts are identified
by the official airport name; e.g., Washington National Airport.
(See [ICAO] Aeronautical Chart).
[ICAO] Aeronautical Chart -
A representation of a portion of the earth, its culture and relief,
specifically designated to meet the requirements of air navigation.
Aeronautical Information Manual -
A primary FAA publication whose purpose is to instruct airmen
about operating in the National Airspace System of the U.S. It provides
basic flight information, ATC Procedures and general instructional information
concerning health, medical facts, factors affecting flight safety, accident
and hazard reporting, and types of aeronautical charts and their use.
[ICAO] Aeronautical Information Publication (AIP) -
A publication issued by or with the authority of a state and
containing aeronautical information of a lasting character essential to
air navigation.
A/FD - (See Airport/Facility Directory)
AFFIRMATIVE -
Yes.
[ICAO] AIP - (See Aeronautical Information Publication)
Airborne Delay -
Amount of delay to be encountered in airborne holding.
Air Carrier District Office (ACDO) -
An FAA field office serving an assigned geographical area, staffed
with Flight Standards personnel serving the aviation industry and the general
public on matters related to the certification and operation of scheduled
air carriers and other large aircraft operations.
Aircraft -
Device(s) that are used or intended to be used for flight in
the air, and when used in air traffic control terminology, may include
the flight crew. (See [ICAO] Aircraft)
[ICAO] Aircraft -
Any machine that can derive support in the atmosphere from the
reactions of the air other than the reactions of the air against the earth's
surface.
Aircraft Approach Category -
A grouping of aircraft based on a speed of 1.3 times the stall
speed in the landing configuration at maximum gross landing weight. An
aircraft shall fit in only one category. If it is necessary to maneuver
at speeds in excess of the upper limit of a speed range for a category,
the minimums for the next higher category should be used. For example,
an aircraft which falls in Category A, but is circling to land at a speed
in excess of 91 knots, should use the approach Category B minimums when
circling to land. The categories are as follows:
a. Category A - Speed less than 91 knots.
b. Category B - Speed 91 knots or more but less than 121 knots.
c. Category C - Speed 121 knots or more but less than 141 knots.
d. Category D - Speed 141 knots or more but less than 166 knots.
e. Category E - Speed 166 knots or more.
(Refer to FAR Parts 1 and 97)
Aircraft Classes -
For the purposes of Wake Turbulence Separation Minima, ATC classifies
aircraft as Heavy, Large, and Small as follows:
a. Heavy - Aircraft capable of takeoff weights of more than
255,000 pounds whether or not they are operating at this weight during
a particular phase of flight.
b. Large - Aircraft of more than 41,000 pounds, maximum certificated
takeoff weight, up to 255,000 pounds.
c. Small - Aircraft of 41,000 pounds or less maximum certificated
takeoff weight.
(Refer to AIM)
Aircraft Situation Display (ASD) -
ASD is a computer system that receives radar track data from
all 20 CONUS ARTCCs, organizes this data into a mosaic display, and presents
it on a computer screen. The display allows the traffic management coordinator
multiple methods of selection and highlighting of individual aircraft or
groups of aircraft. The user has the option of superimposing these aircraft
positions over any number of background displays. These background options
include ARTCC boundaries, any stratum of enroute sector boundaries, fixes,
airways, military and other special use airspace, airports, and geopolitical
boundaries. By using ASD, a coordinator can monitor any number of traffic
situations or the entire systemwide traffic flows.
Aircraft Surge Launch and Recovery (ASLAR) -
Procedures used at USAF bases to provide increased launch and
recovery rates instrument flight rules conditions. ASLAR is based on:
a. Reduced separation between aircraft which is based on time
or distance. Standard arrival separation applies between participants including
multiple flights until the DRAG point. The DRAG point is a published location
on an ASLAR approach where aircraft landing second in a formation slows
to a predetermined airspeed. The DRAG point is the reference point at which
MARSA applies as expanding elements effect separation within a flight or
between subsequent participating flights.
b. ASLAR procedures shall be covered in a Letter of Agreement
between the responsible USAF military ATC facility and the concerned Federal
Aviation Administration facility. Initial Approach Fix spacing requirements
are normally addressed as a minimum.
Air Defense Emergency -
A military emergency condition declared by a designated authority.
This condition exists when an attack upon the continental U.S., Alaska,
Canada, or U.S. installations in Greenland by hostile aircraft or missiles
is considered probable, is imminent, or is taking place. (Refer to AIM)
Air Defense Identification Zone (ADIZ) -
The area of airspace over land or water, extending upward from
the surface, within which the ready identification, the location, and the
control of aircraft are required in the interest of national security.
1. Domestic Air Defense Identification Zone - An ADIZ within
the United States along an international boundary of the United States.
2. Coastal Air Defense Identification Zone - An ADIZ over the
coastal waters of the United States.
3. Distant Early Warning Identification Zone (DEWIZ) - An ADIZ
over the coastal waters of the State of Alaska.
ADIZ locations and operating and flight plan requirements for
civil aircraft operations are specified in FAR Part 99. (Refer to AIM)
Airman's Meteorological Information - (See AIRMET)
AIRMET -
In-flight weather advisories issued only to amend the area forecast
concerning weather phenomena which are of operational interest to all aircraft
and potentially hazardous to aircraft having limited capability because
of lack of equipment, instrumentation, or pilot qualifications. AIRMETs
concern weather of less severity than that covered by SIGMETs or Convective
SIGMETs. AIRMETs cover moderate icing, moderate turbulence, sustained winds
of 30 knots or more at the surface, widespread areas of ceilings less than
1,000 feet and/or visibility less than 3 miles, and extensive mountain
obscurement. (See AWW, SIGMET, Convective SIGMET, and CWA) (Refer to AIM)
Air Navigation Facility -
Any facility used in, available for use in or designed for use
in, aid of air navigation, including landing areas, lights, any apparatus
or equipment for disseminating weather information, for signaling, for
radio directional finding, or for radio or other electrical communication,
and any other structure or mechanism having a similar purpose for guiding
or controlling flight in the air or the landing and takeoff of aircraft.
(See Navigational Aid)
Airport -
An area on land or water that is used or intended to be used
for the landing and takeoff of aircraft and includes its buildings and
facilities, if any.
Airport Acceptance Rate (AAR) -
A dynamic input parameter specifying the number of arriving aircraft
which an airport or airspace can accept from the ARTCC per hour. The AAR
is used to calculate the desired interval between successive arrival aircraft.
Airport Advisory Area -
The area within ten miles of an airport without a control tower
or where the tower is not in operation, and on which a Flight Service Station
is located. (See Local Airport Advisory) (Refer to AIM)
Airport Elevation -
The highest point of an airport's usable runways measured in
feet from mean sea level. (See Touchdown Zone Elevation, [ICAO] Aerodrome
Elevation)
Airport/Facility Directory (A/FD) -
A publication designed primarily as a pilot's operational manual
containing all airports, seaplane bases, and heliports open to the public
including communications data, navigational facilities, and certain special
notices and procedures. This publication is issued in seven volumes according
to geographical area.
Airport Information AID - (See Airport Information Desk)
Airport Information Desk -
An airport unmanned facility designed for pilot self-service
briefing, flight planning, and filing of flight plans. (Refer to AIM)
Airport Lighting -
Various lighting aids that may be installed on an airport. Types
of airport lighting include:
1. Approach Light System (ALS) - An airport lighting facility
which provides visual guidance to landing aircraft by radiating light beams
in a directional pattern by which the pilot aligns the aircraft with the
extended centerline of the runway on his final approach for landing. Capacitor
Discharge Sequential Flashing Lights/Sequenced Flashing Lights may be installed
in conjunction with the ALS at some airports. Types of Approach Light Systems
are:
a. ALSF-1 - Approach Light System with Sequenced Flashing
Lights in ILS Cat I configuration.
b. ALSF-2 - Approach Light System with Sequenced Flashing
Lights in ILS Cat II configuration. The ALSF-2 may operate as an SSALR
when weather conditions permit.
c. SSALF - Simplified Short Approach Light System with
Sequenced Flashing Lights.
d. SSALR - Simplified Short Approach Light System with
Runway Alignment Indicator Lights.
e. MALSF - Medium Intensity Approach Light System with
Sequenced Flashing Lights.
f. MALSR - Medium Intensity Approach Light System with
Runway Alignment Indicator Lights.
g. LDIN - Lead in light system: Consists of one or more
series of flashing lights installed at or near ground level that provides
positive visual guidance along an approach path, either curving or straight,
where special problems exist with hazardous terrain, obstructions, or noise
abatement procedures.
h. RAIL - Runway Alignment Indicator Lights (Sequenced
Flashing Lights which are installed only combination with other light systems).
i. ODALS - Omnidirectional Approach Lighting System consists
of seven omnidirectional flashing lights located in approach area of a
nonprecision runway. Five lights are located on the runway centerline extended
with the first light located 300 feet from the threshold and extending
at equal intervals up to 1,500 feet from the threshold. The other two lights
are located, one on each side of the runway threshold, at a lateral distance
of 40 feet from the runway edge, or 75 feet from the runway edge when installed
on a runway equipped with a VASI. (Refer to Order 6850.2)
2. Runway Lights/Runway Edge Lights - Lights having a prescribed
angle of emission used to define the lateral limits of a runway. Runway
lights are uniformly spaced at intervals of approximately 200 feet, and
the intensity may be controlled or preset.
3. Touchdown Zone Lighting - Two rows of transverse light bars
located symmetrically about the runway centerline normally at 100 foot
intervals. The basic system extends 3,000 feet along the runway.
4. Runway Centerline Lighting - Flush centerline lights spaced
at 50 foot intervals beginning 75 feet from the landing threshold and extending
to within 75 feet of the opposite end of the runway.
5. Threshold Lights - Fixed green lights arranged symmetrically
left and right of the runway centerline, identifying the runway threshold.
6. Runway End Identifier Lights (REIL) - Two synchronized flashing
lights, one on each side of the runway threshold, which provide rapid and
positive identification of the approach end of a particular runway.
7. Visual Approach Slope Indicator (VASI) - An airport lighting
facility providing vertical visual approach slope guidance to aircraft
during approach to landing by radiating a directional pattern of high intensity
read and white focused light beams which indicate to the pilot that he
is "on path" if he sees red/white, "above path" if white/white, and "below
path" if red/red. Some airports serving large aircraft have three bar VASIs
which provide two visual glidepaths to the same runway.
8. Boundary Lights - Lights defining the perimeter of an airport
or landing area. (Refer to AIM)
Airport Marking Aids -
Markings used on runway and taxiway surfaces to identify a specific
runway, a runway threshold, a centerline, a hold line, etc. A runway should
be marked in accordance with its present usage such as:
1. Visual.
2. Nonprecision instrument.
3. Precision instrument. (Refer to AIM)
Airport Reference Point (ARP) -
The approximate geometric center of all usable runway surfaces.
Airport Reservation Office (ARO) -
Office responsible for monitoring the operation of the high density
rule. Receives and processes requests for IFR operations at high density
traffic airports.
Airport Rotating Beacon -
A visual NAVAID operated at many airports. At civil airports,
alternating white and green flashes indicate the location of the airport.
At military airports, the beacons flash alternately white and green, but
are differentiated from civil beacons by dual peaked (two quick) white
flashes between the green flashes. (See Special VFR Operations, Instrument
Flight Rules) (Refer to AIM) (See [ICAO] Aerodrome Beacon)
Airport Surface Detection Equipment (ASDE) -
Radar equipment specifically designed to detect all principal
features on the surface of an airport, including aircraft and vehicular
traffic, and to present the entire image on a radar indicator console in
the control tower. Used to augment visual observation by tower personnel
of aircraft and/or vehicular movements on runways and taxiways.
Airport Surveillance Radar (ASR) -
Approach control radar used to detect and display an aircraft's
position in the terminal area. ASR provides range and azimuth information
but does not provide elevation data. Coverage of the ASR can extend up
to 60 miles.
Airport Taxi Charts -
(See Aeronautical Chart)
Airport Traffic Control Service -
A service provided by a control tower for aircraft operating
on the movement area and in the vicinity of an airport. (See Movement Area,
Tower) (See [ICAO] Aerodrome Control Service)
Airport Traffic Control Tower - (See Tower)
Air Route Surveillance Radar (ARSR) -
Air route traffic control center (ARTCC) radar used primarily
to detect and display an aircraft's position while enroute between terminal
areas. The ARSR enables controllers to provide radar air traffic control
service when aircraft are within the ARSR coverage. In some instances,
ARSR may enable an ARTCC to provide terminal radar services similar to
but usually more limited than those provided by a radar approach control.
Air Route Traffic Control Center (ARTCC) -
A facility established to provide air traffic control service
to aircraft operating on IFR flight plans within controlled airspace and
principally during the enroute phase of light. When equipment capabilities
and controller workload permit, certain advisory/assistance services may
be provided to VFR aircraft. (See NAS Stage A, Enroute Air Traffic Control
Service) (Refer to AIM)
Airspace Hierarchy -
Within the airspace classes, there is a hierarchy and, in the
event of an overlap of airspace: Class A preempts Class B, Class B preempts
Class C, Class C preempts Class D, Class D preempts Class E, and Class
E preempts Class G.
Airspeed -
The speed of an aircraft relative to its surrounding air mass.
The unqualified term "airspeed" means one of the following:
1. Indicated Airspeed - The speed shown on the aircraft airspeed
indicator. This is the speed used in pilot/controller communications under
the general term "airspeed." (Refer to FAR Part 1)
2. True Airspeed - The airspeed of an aircraft relative to undisturbed
air. Used primarily in flight planning and enroute portion of flight. When
used in pilot/controller communications, it is referred to as "true airspeed"
and not shortened to "airspeed."
Airstart -
The starting of an aircraft engine while the aircraft is airborne,
preceded by engine shutdown during training flights or by actual engine
failure.
Air Taxi -
Used to describe a helicopter/VTOL aircraft movement conducted
above the surface but normally not above 100 feet AGL. The aircraft may
proceed either via hover taxi or flight at speeds more than 20 knots. The
pilot is solely responsible for selecting a safe airspeed/altitude for
the operation being conducted. (See Hover Taxi) (Refer to AIM)
Air Traffic -
Aircraft operating in the air or on an airport surface, exclusive
of loading ramps and parking areas. (See [ICAO] Air Traffic)
[ICAO] Air Traffic -
All aircraft in flight or operating on the maneuvering area of
an aerodrome.
Air Traffic Clearance -
An authorization by air traffic control, for the purpose of preventing
collision between known aircraft, for an aircraft to proceed under specified
traffic conditions within controlled airspace. The pilot in command of
an aircraft may not deviate from the provisions of a visual flight rules
(VFR) or instrument flight rules (IFR) air traffic clearance except in
an emergency or unless an amended clearance has been obtained. Additionally,
the pilot may request a different clearance from that which has been issued
by air traffic control (ATC) if information available to the pilot makes
another course of action more practicable or if aircraft equipment limitations
or company procedures forbid compliance with the clearance issued. Pilots
may also request clarification or amendment, as appropriate, any time a
clearance is not fully understood, or considered unacceptable because of
safety of flight. Controllers should, in such instances and to the extent
of operational practicality and safety, honor the pilot's request. Part
91.3(a) states: "The pilot-in-command of an aircraft is directly responsible
for, and is the final authority as to, the operation of that aircraft."
THE PILOT IS RESPONSIBLE TO REQUEST AN AMENDED CLEARANCE if ATC issues
a clearance that would cause a pilot to deviate from a rule or regulation,
or in the pilot's opinion, would place the aircraft in jeopardy. (See ATC
Instructions) (See [ICAO] Air Traffic Control Clearance)
Air Traffic Control (ATC) -
A service operated by appropriate authority to promote the safe,
orderly and expeditious flow of air traffic. (See [ICAO] Air Traffic Control
Service.)
[ICAO] Air Traffic Control Clearance -
Authorization for an aircraft to proceed under conditions specified
by an air traffic control unit.
Note 1: For convenience, the term air traffic control clearance
is frequently abbreviated to clearance when used in appropriate contexts.
Note 2: The abbreviated term clearance may be prefixed by the
words taxi, takeoff, departure, enroute, approach or landing to indicate
the particular portion of flight to which the air traffic control clearance
relates.
Air Traffic Control Service - (See Air Traffic Control)
[ICAO] Air Traffic Control Service -
A service provided for the purpose of:
1. Preventing collisions:
a. Between aircraft; and
b. On the maneuvering area between aircraft and obstructions;
and
2. Expediting and maintaining an orderly flow of air traffic.
Air Traffic Control Specialist -
A person authorized to provide air traffic control service. (See
Air Traffic Control, Flight Service Station) (See [ICAO] Controller)
Air Traffic Control System Command Center (ATCSCC) -
An Air Traffic Operations Service facility consisting of four
operational units.
1. Central Flow Control Function (CFCF). Responsible for coordination
and approval of all major intercenter flow control restrictions on a system
basis in order to obtain maximum utilization of the airspace. (See Quota
Flow Control)
2. Central Altitude Reservation Function (CARF). Responsible
for coordinating, planning, and approving special user requirements under
the Altitude Reservation (ALTRV) concept. (See Altitude Reservation)
3. Airport Reservation Office (ARO). Responsible for approving
IFR flights at designated high density traffic airports (John F. Kennedy,
LaGuardia, O'Hare, and Washington National) during specified hours. (Refer
to FAR Part 93 and Airport/Facility Directory)
4. ATC Contingency Command Post. A facility which enables the
FAA to manage the ATC system when significant portions of the system's
capabilities have been lost or are threatened.
Air Traffic Service -
A generic term meaning:
1. Flight Information Service:
2. Alerting Service
3. Air Traffic Advisory Service:
4. Air Traffic Control Service:
a. Area Control Service,
b. Approach Control Service, or
c. Airport Control Service.
Airway -
A Class E airspace area established in the form of a corridor,
the centerline of which is defined by radio navigational aids. (Refer to
FAR Part 71, AIM) (See Federal Airways) (See [ICAO] Airway)
[ICAO] Airway -
A control area or portion thereof established in the form of
corridor equipped with radio navigational aids.
Airway Beacon -
Used to mark airway segments in remote mountain areas. The light
flashes Morse Code to identify the beacon site. (Refer to AIM)
AIT -
(See Automated Information Transfer)
[ICAO] ALERFA (Alert Phase) -
The code word used to designate an emergency phase wherein apprehension
exists as to the safety of an aircraft and its occupants.
Alert Area - (See Special Use Airspace)
Alert Notice (ALNOT) -
A request originated by a flight service station (FSS) or an
air route traffic control center (ARTCC) for an extensive communication
search for overdue, unreported, or missing aircraft.
Alerting Service -
A service provided to notify appropriate organizations regarding
aircraft in need of search and rescue aid and assist such organizations
as required.
Along Track Distance (LTD) -
The distance measured from a point-in-space by systems using
area navigation reference capabilities that are not subject to slant range
errors.
ALNOT - (See Alert Notice)
Alphanumeric Display -
Letters and numerals used to show identification, altitude, beacon
code, and other information concerning a target on a radar display. (See
Automated Radar Terminal Systems, NAS Stage A)
[ICAO] Alternate Aerodrome -
An aerodrome specified in the flight plan to which a flight may
proceed when it becomes inadvisable to land at the aerodrome of intended
landing.
Note: The aerodrome from which a flight departs may also be
an enroute or a destination alternate aerodrome for the flight.
Alternate Airport -
An airport at which an aircraft may land if a landing at the
intended airport becomes inadvisable. (See FAA term [ICAO] Alternate Aerodrome)
Altimeter Setting -
The barometric pressure reading used to adjust a pressure altimeter
for variations in existing atmospheric pressure or to the standard altimeter
setting (29.92). (Refer to FAR Part 91, AIM)
Altitude -
The height of a level, point, or object measured in feet Above
Ground Level (AGL) or from Mean Sea Level (MSL). (See Flight Level)
1. MSL Altitude - Altitude expressed in feet measured from mean
sea level.
2. AGL Altitude - Altitude expressed in feet measured above
ground level.
3. Indicated Altitude - The altitude as shown by an altimeter.
On a pressure or barometric altimeter it is altitude as shown uncorrected
for instrument error and uncompensated for variation from standard atmospheric
conditions.
(See [ICAO] Altitude)
[ICAO] Altitude -
The vertical distance of a level, a point or an object considered
as a point, measured from mean sea level (MSL).
ALTITUDE READOUT -
An aircraft's altitude, transmitted via the Mode C transponder
feature, that is visually displayed in 100 foot increments on a radar scope
having readout capability. (See Automated Radar Terminal Systems, NAS Stage
A, Alphanumeric Display) (Refer to AIM)
Altitude Reservation (ALTRV) -
Airspace utilization under prescribed conditions normally employed
for the mass movement of aircraft or other special user requirements which
cannot otherwise be accomplished. ALTRVs are approved by the appropriate
FAA facility. (See Air Traffic Control System Command Center)
Altitude Restriction -
An altitude or altitudes, stated in the order flown, which are
to be maintained until reaching a specific point or time. Altitude restrictions
may be issued by ATC due to traffic, terrain, or other airspace considerations.
ALTITUDE RESTRICTIONS ARE CANCELED -
Adherence to previously imposed altitude restrictions is no longer
required during a climb or descent.
ALTRV - (See Altitude Reservation)
AMVER - (See Automated Mutual Assistance Vessel Rescue System)
Approach Clearance -
Authorization by ATC for a pilot to conduct an instrument approach.
The type of instrument approach for which a clearance and other pertinent
information is provided in the approach clearance when required. (See Instrument
Approach Procedure, Cleared for Approach) (Refer to AIM and FAR Part 91)
Approach Control Facility -
A terminal ATC facility that provides approach control service
in a terminal area. (See Approach Control Service, Radar Approach Control
Facility)
Approach Control Service -
Air traffic control service provided by an approach control facility
for arriving and departing VFR/IFR aircraft and, on occasion, enroute aircraft.
At some airports not served by an approach control facility, the ARTCC
provides limited approach control service. (Refer to AIM) (See [ICAO] Approach
Control Service)
[ICAO] Approach Control Service -
Air traffic control service for arriving or departing controlled
flights.
Approach Gate -
An imaginary point used within ATC as a basis for vectoring aircraft
to the final approach course. The gate will be established along the final
approach course 1 mile from the outer marker (or the fix used in lieu of
the outer marker) on the side away from the airport for precision approaches
and 1 mile from the final approach fix on the side away from the airport
for nonprecision approaches. In either case when measured along the final
approach course, the gate will be no closer than 5 miles from the landing
threshold.
Approach Light System - (See Airport Lighting)
Approach Sequence -
The order in which aircraft are positioned while on approach
or awaiting approach clearance. (See Landing Sequence) (See [ICAO] Approach
Sequence)
[ICAO] Approach Sequence -
The order in which two or more aircraft are cleared to approach
to land at the aerodrome.
APPROACH SPEED -
The recommended speed contained in aircraft manuals used by pilots
when making an approach to landing. This speed will vary for different
segments of an approach as well as for aircraft weight and configuration.
[ICAO] Appropriate ATS Authority -
{New-98-3 Revised February 26, 1998}
The relevant authority designated by the State responsible for
providing air traffic services in the airspace concerned. In the United
States, the "appropriate ATS authority" is the Program Director for Air
Traffic Operations, ATO-1.
Appropriate Authority -
1. Regarding flight over the high seas: the relevant authority
is the State of Registry.
2. Regarding flight over other than the high seas: the relevant
authority is the State having sovereignty over the territory being overflown.
APPROPRIATE OBSTACLE CLEARANCE MINIMUM ALTITUDE -
Any of the following:
(See Minimum IFR Altitude (MIA))
(See Minimum Enroute Altitude (MEA))
(See Minimum Obstruction Clearance Altitude (MOCA))
(See Minimum Vectoring Altitude (MVA))
APPROPRIATE TERRAIN CLEARANCE MINIMUM ALTITUDE -
Any of the following:
(See Minimum IFR Altitude (MIA))
(See Minimum Enroute Altitude (MEA))
(See Minimum Obstruction Clearance Altitude (MOCA))
(See Minimum Vectoring Altitude (MVA))
Apron -
A defined area on an airport or heliport intended to accommodate
aircraft for purposes of loading or unloading passengers or cargo, refueling,
parking, or maintenance. With regard to seaplanes, a ramp is used for access
to the apron from the water. (See [ICAO] Apron)
[ICAO] Apron -
A defined area, on a land aerodrome, intended to accommodate
aircraft for purposes of loading or unloading passengers, mail or cargo,
refueling, parking or maintenance.
Arc -
The track over the ground of an aircraft flying at a constant
distance from a navigational aid by reference to distance measuring equipment
(DME).
[ICAO] Area Control Center (ACC) -
An ICAO term for an air traffic control facility primarily responsible
for ATC services being provided IFR aircraft during the enroute phase of
flight. The U.S. equivalent facility is an air route traffic control center
(ARTCC).
Area Navigation -
A method of navigation that permits aircraft operation on any
desired course within the coverage of station referenced navigation signals
or within the limits of a self-contained system capability. Random area
navigation routes are direct routes, based on area navigation capability,
between waypoints defined in terms of latitude/longitude coordinates, degree/distance
fixes, or offsets from published or established routes/airways at a specified
distance and direction. The major types of equipment are:
a. VORTAC referenced or Course Line Computer (CLC) systems,
which account for the greatest number of RNAV units in use. To function,
the CLC must be within the service range of a VORTAC.
b. OMEGA/VLF, although two separate systems, can be considered
as one operationally. A long range navigation system based upon Very Low
Frequency radio signals transmitted from a total of 17 stations worldwide.
c. Inertial (INS) systems, which are totally self-contained
and require no information from external references. They provide aircraft
position and navigation information in response to signals resulting from
inertial effects on components within the system.
d. MLS Area Navigation (MLS/RNAV), which provides area navigation
with reference to an MLS ground facility.
e. LORAN C is a long range radio navigation system that uses
ground waves transmitted at low frequency to provide user position information
at ranges of up to 600 to 1,200 nautical miles at both enroute and approach
altitudes. The useable signal coverage areas are determined by the signal
to noise ratio, the envelope to cycle difference, and the geometric relationship
between the positions of the user and the transmitting stations.
f. GPS is a space-base radio positioning, navigation, and time-transfer
system. The system provides highly accurate position and velocity information,
and precise time, on a continuous global basis, to an unlimited number
of properly equipped users. The system is unaffected by weather, and provides
a worldwide common grid reference system.
(See [ICAO] Area Navigation)
Area Navigation [ICAO] -
A method of navigation which permits aircraft operation on any
desired flight path within the coverage of station referenced navigation
aids or within the limits of the capability of self-contained aids, or
a combination of these.
AREA NAVIGATION (RNAV) APPROACH CONFIGURATION:
a. STANDARD T - An RNAV approach whose design allows direct flight
to any one of three initial approach fixes (IAF) and eliminates the need
for procedure turns. The standard design is to align the procedure on the
extended centerline with the missed approach point (MAP) at the runway
threshold, the final approach fix (FAF), and the initial approach/intermediate
fix (IAF/IF). The other two IAF's will be established perpendicular to
the IF.
b. MODIFIED T - An RNAV approach design for single or multiple
runways where terrain or operational constraints do not allow for the standard
T. The "T" may be modified by increasing or decreasing the angle from the
corner IAF(s) to the IF or by eliminating one or both corner IAF's.
c. STANDARD I - An RNAV approach design for a single runway with
both corner IAF's eliminated. Course reversal or radar vectoring may be
required at busy terminals with multiple runways.
d. TERMINAL ARRIVAL AREA (TAA) - The TAA is controlled airspace
established in conjunction with the Standard or Modified T and I RNAV approach
configurations. In the standard TAA, there are three areas: straight-in,
left base, and right base. The arc boundaries of the three areas of the
TAA are published portions of the approach and allow aircraft to transition
from the en route structure direct to the nearest IAF. TAA's will also
eliminate or reduce feeder routes, departure extensions, and procedure
turns or course reversal.
1. STRAIGHT-IN AREA, A 30NM arc centered on the IF bounded by
a straight line extending through the IF perpendicular to the intermediate
course.
2. LEFT BASE AREA, A 30NM arc centered on the right corner IAF.
The area shares a boundary with the straight-in area except that it extends
out for 30NM from the IAF and is bounded on the other side by a line extending
from the IF through the FAF to the arc.
3. RIGHT BASE AREA, A 30NM arc centered on the left corner IAF.
The area shares a boundary with the straight-in area except that it extends
out for 30NM from the IAF and is bounded on the other side by a line extending
from the IF through the FAF to the arc.
ARINC -
An acronym for Aeronautical Radio, Inc., a corporation largely
owned by a group of airlines. ARINC is licensed by the FCC as an aeronautical
station and contracted by the FAA to provide communications support for
air traffic control and meteorological services in portions of international
airspace.
Army Aviation Flight Information Bulletin (USAFIB) -
A bulletin that provides air operation data covering Army, National
Guard, and Army Reserve aviation activities.
ARO - (See Airport Reservation Office)
Arresting System -
A safety device consisting of two major components, namely, engaging
or catching devices and energy absorption devices for the purpose of arresting
both tailhook and/or nontailhook equipped aircraft. It is used to prevent
aircraft from overrunning runways when the aircraft cannot be stopped after
landing or during aborted takeoff. Arresting systems have various names;
e.g., arresting gear, hook device, wire barrier cable. (See Abort) (Refer
to AIM)
Arrival Aircraft Interval (AAI) -
An internally generated program in hundredths of minutes based
upon the AAR. AAI is the desired optimum interval between successive arrival
aircraft over the vertex.
Arrival Center -
The ARTCC having jurisdiction for the impacted airport.
Arrival Delay (ADLY) -
A parameter which specifies a period of time in which no aircraft
will be metered for arrival at the specified airport.
Arrival Sector -
An operational control sector containing one or more meter fixes.
Arrival Sector Advisory List -
An ordered list of data on arrivals displayed at the PVD of the
sector which controls the meter fix.
Arrival Sequencing Program (ASP) -
The automated program designed to assist in sequencing aircraft
destined for the same airport.
Arrival Time -
The time an aircraft touches down on arrival.
ARSR - (See Air Route Surveillance Radar)
ARTCC - (See Air Route Traffic Control Center)
ARTS - (See Automated Radar Terminal System)
ASD - (See Aircraft Situation Display)
ASDA - (See Accelerate-Stop Distance Available)
[ICAO] ASDA - (See [ICAO] Accelerate-Stop Distance Available)
ASDE - (See Airport Surface Detection Equipment)
ASLAR - (See Aircraft Surge Launch and Recovery)
ASP - (See Arrival Sequencing Program)
ASR - (See Airport Surveillance Radar)
ASR Approach - (See Surveillance Approach)
ATC - (See Air Traffic Control)
ATCAA - (See ATC Assigned Airspace)
ATC Advises -
Used to prefix a message of noncontrol information when it is
relayed to an aircraft by other than an air traffic controller. (See Advisory)
ATC Assigned Airspace (ATCAA) -
Airspace of defined vertical/lateral limits, assigned by ATC,
for the purpose of providing air traffic segregation between the specified
activities being conducted within the assigned airspace and other IFR air
traffic. (See Special Use Airspace)
ATC Clearance - (See Air Traffic Clearance)
ATC Clears -
Used to prefix an ATC clearance when it is relayed to an aircraft
by other than an air traffic controller.
ATC Instructions -
Directives issued by air traffic control for the purpose of requiring
a pilot to take specific actions; e.g., "Turn left heading two five zero,"
"Go around," "Clear the runway." (Refer to FAR Part 91)
ATCRBS - (See Radar)
ATC Requests -
Used to prefix an ATC request when it is relayed to an aircraft
by other than an air traffic controller.
ATCSCC - (See Air Traffic Control System Command Center)
ATCSCC DELAY FACTOR -
The amount of delay calculated to be assigned prior to departure.
ATCT - (See Tower)
ATIS - (See Automatic Terminal Information Service)
[ICAO] ATIS - (See [ICAO] Automatic Terminal Information Service)
[ICAO] ATS Route -
A specified route designed for the flow of traffic as necessary
for the provision of air traffic services.
Note: The term "ATS Route" is used to mean airway, advisory
route, controlled or uncontrolled route, arrival or departure, etc.
Autoland Approach -
An autoland approach is a precision instrument approach to touchdown
and, in some cases, through the landing rollout. An autoland approach is
performed by the aircraft autopilot which is receiving position information
and/or steering commands from on board navigation equipment. (See Coupled
Approach)
Note: Autoland and coupled approaches are flown in VFR and IFR.
It is common for carriers to require their crews to fly coupled approaches
and autoland approaches (if certified) when the weather conditions are
less than approximately 4,000 RVR.
Automated Information Transfer (AIT) -
A precoordinated process, specifically defined in facility directives,
during which a transfer of altitude control and/or radar identification
is accomplished without verbal coordination between controllers using information
communicated in a full data block.
Automated Mutual Assistance Vessel Rescue System -
A facility which can deliver, in a matter of minutes, a surface
picture (SURPIC) of vessels in the area of a potential or actual search
and rescue incident, including their predicted positions and their characteristics.
(See FAA Order 7110.65, paragraph 10-7-4, In-flight Contingencies).
Automated Radar Terminal Systems (ARTS) -
The generic term for the ultimate in functional capability afforded
by several automation systems. Each differs in functional capabilities
and equipment. ARTS plus a suffix roman numeral denotes a specific system.
A following letter indicates a major modification to that system. In general,
an ARTS displays for the terminal controller aircraft identification, flight
plan data, other flight associated information; e.g., altitude, speed,
and aircraft position symbols in conjunction with his radar presentation.
Normal radar coexists with the alphanumeric display. In addition to enhancing
visualization of the air traffic situation, ARTS facilitate intrafacility
and interfacility transfer and coordination of flight information. These
capabilities are enabled by specially designed computers and subsystems
tailored to the radar and communications equipments and operational requirements
of each automated facility. Modular design permits adoption of improvements
in computer software and electronic technologies as they become available
while retaining the characteristics unique to each system.
1. ARTS II - A programmable nontracking, computer aided display
subsystem capable of modular expansion. ARTS II systems provide a level
of automated air traffic control capability at terminals having low to
medium activity. Flight identification and altitude may be associated with
the display of secondary radar targets. The system has the capability of
communicating with ARTCCs and other ARTS II, IIA, III, and IIIA facilities.
2. ARTS IIA - A programmable radar tracking computer subsystem
capable of modular expansion. The ARTS IIA detects, tracks, and predicts
secondary radar targets. The targets are displayed by means of computer
generated symbols, ground speed, and flight plan data. Although it does
not track primary radar targets, they are displayed coincident with the
secondary radar as well as the symbols and alphanumerics. The system has
the capability of communicating with ARTCCs and other ARTS II, IIA, III,
and IIIA facilities.
3. ARTS III - The Beacon Tracking Level (BTL) of the modular
programmable automated radar terminal system in use at medium to high activity
terminals. ARTS III detects, tracks, and predicts secondary radar derived
aircraft targets. These are displayed by means of computer generated symbols
and alphanumeric characters depicting flight identification, aircraft altitude,
ground speed, and flight plan data. Although it does not track primary
targets, they are displayed coincident with the secondary radar as well
as the symbols and alphanumerics. The system has the capability of communicating
with ARTCCs and other ARTS III facilities.
4. ARTS IIIA - The Radar Tracking and Beacon Tracking Level
(RT & BTL) of the modular, programmable automated radar terminal system.
ARTS IIIA detects, tracks, and predicts primary as well as secondary radar
derived aircraft targets. This more sophisticated computer driven system
upgrades the existing ARTS III system by providing improved tracking, continuous
data recording, and fail-soft capabilities.
Automatic Altitude Report - (See Altitude Readout)
Automatic Altitude Reporting -
That function of a transponder which responds to Mode C interrogations
by transmitting the aircraft's altitude in 100 foot increments.
Automatic Carrier Landing System (ACLS) -
U.S. Navy final approach equipment consisting of precision tracking
radar coupled to a computer data link to provide continuous information
to the aircraft, monitoring capability to the pilot, and a backup approach
system.
Automatic Direction Finder (ADF) -
An aircraft radio navigation system which senses and indicates
the direction to a L/MF nondirectional radio beacon (NDB) ground transmitter.
Direction is indicated to the pilot as a magnetic bearing or as a relative
bearing to the longitudinal axis of the aircraft depending on the type
of indicator installed in the aircraft. In certain applications, such as
military, ADF operations may be based on airborne and ground transmitters
in the VHF/UHF frequency spectrum. (See Bearing, Nondirectional Beacon)
Automatic Terminal Information Service (ATIS) -
The continuous broadcast of recorded noncontrol information in
selected terminal areas. Its purpose is to improve controller effectiveness
and to relieve frequency congestion by automating the repetitive transmission
of essential but routine information; e.g., "Los Angeles information Alfa.
One three zero zero Coordinated Universal Time. Weather measured ceiling
two thousand overcast, visibility three, haze, smoke, temperature seven
one, dew point five seven, wind two five zero at five, altimeter two niner
six. ILS Runway Two Five Left approach in use, Runway Two Five Right closed,
advise you have Alfa." (Refer to AIM) (See [ICAO] Automatic Terminal Information
Service)
[ICAO] Automatic Terminal Information Service -
The provision of current, routine information to arriving and
departing aircraft by means of continuous and repetitive broadcasts throughout
the day or a specified portion of the day.
Autorotation -
A rotorcraft flight condition in which the lifting rotor is driven
entirely by action of the air when the rotorcraft is in motion.
1. Autorotative Landing/Touchdown Autorotation - Used by a pilot
to indicate that he will be landing without applying power to the rotor.
2. Low Level Autorotation - Commences at an altitude well below
the traffic pattern, usually below 100 feet AGL and is used primarily for
tactical military training.
3. 180 degrees Autorotation - Initiated from a downwind heading
and is commenced well inside the normal traffic pattern. "Go around" may
not be possible during the latter part of this maneuver.
{New-98-3 Added February 26, 1998}
Available Landing Distance (ALD) -
The portion of a runway available for landing and roll-out for
aircraft cleared for LAHSO. This distance is measured from the landing
threshold to the hold-short point.
Aviation Weather Service -
A service provided by the National Weather Service (NWS) and
FAA which collects and disseminates pertinent weather information for pilots,
aircraft operators, and ATC. Available aviation weather reports and forecasts
are displayed at each NWS office and FAA FSS. (See Enroute Flight Advisory
Service, Transcribed Weather Broadcast, Weather Advisory, Pilots Automatic
Telephone Weather Answering Service) (Refer to AIM)
AWW - (See Severe Weather Forecast Alerts)
Azimuth (MLS) -
A magnetic bearing extending from an MLS navigation facility.
Note: azimuth bearings are described as magnetic and are referred
to as "azimuth" in radio telephone communications.
B
Back-Taxi - A term used by air traffic controllers to taxi an aircraft
on the runway opposite to the traffic flow. The aircraft may be instructed
to back-taxi to the beginning of the runway or at some point before reaching
the runway end for the purpose of departure or to exit the runway.
Base Leg - (See Traffic Pattern)
Beacon - (See Radar, Nondirectional Beacon, Marker Beacon, Airport Rotating Beacon, Aeronautical Beacon, Airway Beacon)
Bearing -
The horizontal direction to or from any point, usually measured
clockwise from true north, magnetic north, or some other reference point
through 360 degrees. (See Nondirectional Beacon)
Below Minimums -
Weather conditions below the minimums prescribed by regulation
for the particular action involved; e.g., landing minimums, takeoff minimums.
Blast Fence -
A barrier that is used to divert or dissipate jet or propeller
blast.
Blind Speed -
The rate of departure or closing of a target relative to the
radar antenna at which cancellation of the primary radar target by moving
target indicator (MTI) circuits in the radar equipment causes a reduction
or complete loss of signal. (See [ICAO] Blind Velocity)
Blind Spot -
An area from which radio transmissions and/or radar echoes cannot
be received. The term is also used to describe portions of the airport
not visible from the control tower.
BLIND TRANSMISSION - (See Transmitting in the Blind)
[ICAO] Blind Velocity -
The radial velocity of a moving target such that the target is
not seen on primary radars fitted with certain forms of fixed echo suppression.
Blind Zone - (See Blind Spot)
BLOCKED -
Phraseology used to indicate that a radio transmission has been
distorted or interrupted due to multiple simultaneous radio transmissions.
Boundary Lights - (See Airport Lighting)
BRAKING ACTION (GOOD, FAIR, POOR, OR NIL) -
A report of conditions on the airport movement area providing
a pilot with a degree/quality of braking that he might expect. Braking
action is reported in terms of good, fair, poor, or nil. (See Runway Condition
Reading)
Braking Action Advisories -
When tower controllers have received runway braking action reports
which include the terms "poor" or "nil," or whenever weather conditions
are conducive to deteriorating or rapidly changing runway braking conditions,
the tower will include on the ATIS broadcast the statement, "BRAKING ACTION
ADVISORIES ARE IN EFFECT." During the time Braking Action Advisories are
in effect, ATC will issue the latest braking action report for the runway
in use to each arriving and departing aircraft. Pilots should be prepared
for deteriorating braking conditions and should request current runway
condition information if not volunteered by controllers. Pilots should
also be prepared to provide a descriptive runway condition report to controllers
after landing.
Breakout -
A technique to direct aircraft out of the approach stream. In
the context of close parallel operations, a breakout is used to direct
threatened aircraft away from a deviating aircraft.
Broadcast -
Transmission of information for which an acknowledgement is not
expected. (See [ICAO] Broadcast)
[ICAO] Broadcast -
A transmission of information relating to air navigation that
is not addressed to a specific station or stations.
C
Calculated Landing Time (CLT) -
A term that may be used in place of tentative or actual calculated
landing time, whichever applies.
Call Up -
Initial voice contact between a facility and an aircraft, using
the identification of the unit being called and the unit initiating the
call. (Refer to AIM)
Call for Release (CFR) -
Wherein the overlying ARTCC requires a terminal facility to initiate
verbal coordination to secure ARTCC approval for release of a departure
into the enroute environment.
Canadian Minimum Navigation Performance Specification (CMNPS) Airspace
-
That portion of Canadian domestic airspace within which MNPS
separation may be applied.
Cardinal Altitudes -
"Odd" or "Even" thousand foot altitudes or flight levels; e.g.,
5,000, 6,000, 7,000, FL 250, FL 260, FL 270. (See Altitude, Flight Level)
Cardinal Flight Levels - (See Cardinal Altitudes)
CAT - (See Clear Air Turbulence)
CDT Programs - (See Controlled Departure Time Programs)
Ceiling -
The heights above the earth's surface of the lowest layer of
clouds or obscuring phenomena that is reported as "broken," "overcast,"
or "obscuration," and not classified as "thin" or "partial". (See [ICAO]
Ceiling)
[ICAO] Ceiling -
The height above the ground or water of the base of the lowest
layer of cloud below 6,000 meters (20,000 feet) covering more than half
the sky.
CENRAP - (See Center Radar Arts Presentation/Processing)
CENRAP-Plus - (See Center Radar Arts Presentation/Processing-Plus)
Center - (See Air Route Traffic Control Center)
Center's Area -
The specified airspace within which an air route traffic control
center (ARTCC) provides air traffic control and advisory service. (See
Air Route Traffic Control Center) (Refer to AIM)
Center Radar Arts Presentation/Processing (CENRAP) -
A computer program developed to provide a backup system for airport
surveillance radar in the event of a failure or malfunction. The program
uses Air Route Traffic Control Center Radar for the processing and presentation
of data on the ARTS IIA or IIIA displays.
Center Radar Arts Presentation/Processing-Plus (CENRAP-Plus) -
A computer program developed to provide a backup system for airport
surveillance radar in the event of a terminal secondary radar system failure.
The program uses a combination of Air Route Traffic Control Center Radar
and terminal airport surveillance radar primary targets displayed simultaneously
for the processing and presentation of data on the ARTS IIA or IIIA displays.
Center Weather Advisory (CWA) -
An unscheduled weather advisory issued by Center Weather Service
Unit meteorologists for ATC use to alert pilots of existing or anticipated
adverse weather conditions within the next 2 hours. A CWA may modify or
redefine a SIGMET. (See AWW, SIGMET, Convective SIGMET, and AIRMET) (Refer
to AIM)
Central East Pacific (CEP) -
An organized route system between the U.S. West Coast and Hawaii.
CEP - (See Central East Pacific)
CERAP - (See Combined Center - RAPCON)
CFR - (See Call For Release)
Chaff -
Thin, narrow metallic reflectors of various lengths and frequency
responses, used to reflect radar energy. These reflectors when dropped
from aircraft and allowed to drift downward result in large targets on
the radar display.
Charted VFR Flyways -
Charted VFR Flyways are flight paths recommended for use to bypass
areas heavily traversed by large turbine powered aircraft. Pilot compliance
with recommended flyways and associated altitudes is strictly voluntary.
VFR Flyway Planning charts are published on the back of existing VFR Terminal
Area charts.
Charted Visual Flight Procedure Approach -
An approach conducted while operating on an instrument flight
rules (IFR) flight plan which authorizes the pilot of an aircraft to proceed
visually and clear of clouds to the airport via visual landmarks and other
information depicted on a charted visual flight procedure. This approach
must be authorized and under the control of the appropriate air traffic
control facility. Weather minimums required are depicted on the chart.
CHASE -
An aircraft flown in proximity to another aircraft normally to
observe its performance during training or testing.
Chase Aircraft - (See Chase)
Circle-to-Land Maneuver -
A maneuver initiated by the pilot to align the aircraft with
a runway for landing when a straight-in landing from an instrument approach
is not possible or is not desirable. This maneuver is made only after ATC
authorization has been obtained and the pilot has established required
visual reference to the airport. (See Circle to Runway, Landing Minimums)
(Refer to AIM)
CIRCLE TO RUNWAY (RUNWAY NUMBER) -
Used by ATC to inform the pilot that he must circle to land because
the runway in use is other than the runway aligned with the instrument
approach procedure. When the direction of the circling maneuver in relation
to the airport/runway is required, the controller will state the direction
(eight cardinal compass points) and specify a left or right downwind or
base leg as appropriate; e.g., "Cleared VOR Runway Three Six Approach circle
to Runway Two Two," or "Circle northwest of the airport for a right downwind
to Runway Two Two." (See Circle-to-Land Maneuver, Landing Minimums) (Refer
to AIM)
Circling Approach - (See Circle-to-Land Maneuver)
Circling Maneuver - (See Circle-to-Land Maneuver)
Circling Minima - (See Landing Minimums)
Class A Airspace -
(See Controlled Airspace)
Class B Airspace -
(See Controlled Airspace)
Class C Airspace -
(See Controlled Airspace)
Class D Airspace -
(See Controlled Airspace)
Class E Airspace -
(See Controlled Airspace)
Class G Airspace -
That airspace not designated as Class A, B, C, D or E.
Clear Air Turbulence (CAT) -
Turbulence encountered in air where no clouds are present. This
term is commonly applied to high level turbulence associated with windshear.
CAT is often encountered in the vicinity of the jet stream. (See Windshear,
Jet Stream)
Clear of the Runway -
1. A taxiing aircraft, which is approaching a runway, is clear
of the runway when all parts of the aircraft are held short of the applicable
holding position marking.
2. A pilot or controller may consider an aircraft, which is exiting
or crossing a runway, to be clear of the runway when all parts of the aircraft
are beyond the runway edge and there is no ATC restriction to its continued
movement beyond the applicable holding position marking.
3. Pilots and controllers shall exercise good judgement to ensure
that adequate separation exists between all aircraft on runways and taxiways
at airports with inadequate runway edge lines or holding position markings.
CLEARANCE - (See Air Traffic Clearance)
Clearance Limit -
The fix, point, or location to which an aircraft is cleared when
issued an air traffic clearance. (See [ICAO] Clearance Limit)
[ICAO] Clearance Limit -
The point of which an aircraft is granted an air traffic control
clearance.
CLEARANCE VOID IF NOT OFF BY (TIME) -
Used by ATC to advise an aircraft that the departure clearance
is automatically canceled if takeoff is not made prior to a specified time.
The pilot must obtain a new clearance or cancel his IFR flight plan if
not off by the specified time. (See [ICAO] Clearance Void Time)
[ICAO] Clearance Void Time -
A time specified by an air traffic control unit at which a clearance
ceases to be valid unless the aircraft concerned has already taken action
to comply therewith.
{New-98-8 Revised August 13, 1998. "DP" was "SID"}
CLEARED AS FILED -
Means the aircraft is cleared to proceed in accordance with the
route of flight filed in the flight plan. This clearance does not include
the altitude, DP, or DP Transition. (See Request Full Route Clearance)
(Refer to AIM)
CLEARED (Type Of) APPROACH -
ATC authorization for an aircraft to execute a specific instrument
approach procedure to an airport; e.g., "Cleared for ILS Runway Three Six
Approach." (See Instrument Approach Procedure, Approach Clearance) (Refer
to AIM) (Refer to FAR Part 91)
CLEARED APPROACH -
ATC authorization for an aircraft to execute any standard or
special instrument approach procedure for that airport. Normally, an aircraft
will be cleared for a specific instrument approach procedure. (See Instrument
Approach Procedure, Cleared (Type of) Approach) (Refer to AIM) (Refer to
FAR Part 91)
CLEARED FOR TAKEOFF -
ATC authorization for an aircraft to depart. It is predicated
on known traffic and known physical airport conditions.
CLEARED FOR THE OPTION -
ATC authorization for an aircraft to make a touch and go, low
approach, missed approach, stop and go, or full stop landing at the discretion
of the pilot. It is normally used in training so that an instructor can
evaluate a student's performance under changing situations. (See Option
Approach) (Refer to AIM)
CLEARED THROUGH -
ATC authorization for an aircraft to make intermediate stops
at specified airports without refiling a flight plan while enroute to the
clearance limit.
CLEARED TO LAND -
ATC authorization for an aircraft to land. It is predicated on
known traffic and known physical airport conditions.
Clearway -
An area beyond the takeoff runway under the control of airport
authorities within which terrain or fixed obstacles may not extend above
specified limits. These areas may be required for certain turbine powered
operations and the size and upward slope of the clearway will differ depending
on when the aircraft was certificated. (Refer to FAR Part 1)
Climbout -
That portion of flight operation between takeoff and the initial
cruising altitude.
CLIMB TO VFR -
ATC authorization for an aircraft to climb to VFR conditions
within Class B, C, D, and E surface areas when the only weather limitation
is restricted visibility. The aircraft must remain clear of clouds while
climbing to VFR. (See Special VFR) (Refer to AIM)
{New-98-3 Revised February 26, 1998}
CLOSE PARALLEL RUNWAYS -
Two parallel runways whose extended centerlines are separated
by less than 4,300 feet, having a Precision Runway Monitoring (PRM) system
that permits simultaneous independent ILS approaches.
Closed Runway -
A runway that is unusable for aircraft operations. Only the airport
management/military operations office can close a runway.
Closed Traffic -
Successive operations involving takeoffs and landings or low
approaches where the aircraft does not exit the traffic pattern.
CLT - (See Calculated Landing Time)
Clutter -
In radar operations, clutter refers to the reception and visual
display of radar returns caused by precipitation, chaff, terrain, numerous
aircraft targets, or other phenomena. Such returns may limit or preclude
ATC from providing services based on radar. (See Ground Clutter, Chaff,
Precipitation, Target) (See [ICAO] Radar Clutter)
CMNPS - (See Canadian Minimum Navigation Performance Specification Airspace)
Coastal Fix -
A navigation aid or intersection where an aircraft transitions
between the domestic route structure and the oceanic route structure.
Codes -
The number assigned to a particular multiple pulse reply signal
transmitted by a transponder. (See Discrete Code)
Combined Center - RAPCON (CERAP) -
An air traffic facility which combines the functions of an ARTCC
and a radar approach control facility. (See Air Route Traffic Control Center,
Radar Approach Control Facility)
Common Point -
A significant point over which two or more aircraft will report
passing or have reported passing before proceeding on the same or diverging
tracks. To establish/maintain longitudinal separation, a controller may
determine a common point not originally in the aircraft's flight plan and
then clear the aircraft to fly over the point. See significant point.
Common Portion - (See Common Route)
Common Route -
That segment of a North American Route between the inland navigation
facility and the coastal fix.
Common Traffic Advisory Frequency (CTAF) -
A frequency designed for the purpose of carrying out airport
advisory practices while operating to or from an airport without an operating
control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency
and is identified in appropriate aeronautical publications. (Refer to AC
90-42)
Compass Locator -
A low power, low or medium frequency (L/MF) radio beacon installed
at the site of the outer or middle marker of an instrument landing system
(ILS). It can be used for navigation at distances of approximately 15 miles
or as authorized in the approach procedure.
1. Outer Compass Locator (LOM) - A compass locator installed
at the site of the outer marker of an instrument landing system. (See Outer
Marker)
2. Middle Compass Locator (LMM) - A compass locator installed
at the site of the middle marker of an instrument landing system. (See
Middle Marker) (See [ICAO] Locator)
Compass Rose -
A circle, graduated in degrees, printed on some charts or marked
on the ground at an airport. It is used as a reference to either true or
magnetic direction.
Composite Flight Plan -
A flight plan which specifies VFR operation for one portion of
flight and IFR for another portion. It is used primarily in military operations.
(Refer to AIM)
Composite Route System -
An organized oceanic route structure, incorporating reduced lateral
spacing between routes, in which composite separation is authorized.
Composite Separation -
A method of separating aircraft in a composite route system where,
by management of route and altitude assignments, a combination of half
the lateral minimum specified for the area concerned and half the vertical
minimum is applied.
Compulsory Reporting Points -
Reporting points which must be reported to ATC. They are designated
on aeronautical charts by solid triangles or filed in a flight plan as
fixes selected to define direct routes. These points are geographical locations
which are defined by navigation aids/fixes. Pilots should discontinue position
reporting over compulsory reporting points when informed by ATC that their
aircraft is in "radar contact."
Conflict Alert -
A function of certain air traffic control automated systems designed
to alert radar controllers to existing or pending situations between tracked
targets (known IFR or VFR aircraft) that require his immediate attention/action.
(See Mode C Intruder Alert)
CONSOLAN -
A low frequency, long distance NAVAID used principally for transoceanic
navigation.
Contact -
1. Establish communication with (followed by the name of the
facility and, if appropriate, the frequency to be used).
2. A flight condition wherein the pilot ascertains the attitude
of his aircraft and navigates by visual reference to the surface. (See
Contact Approach, Radar Contact)
CONTACT APPROACH -
An approach wherein an aircraft on an IFR flight plan, having
an air traffic control authorization, operating clear of clouds with at
least 1 mile flight visibility and a reasonable expectation of continuing
to the destination airport in those conditions, may deviate from the instrument
approach procedure and proceed to the destination airport by visual reference
to the surface. This approach will only be authorized when requested by
the pilot and the reported ground visibility at the destination airport
is at least 1 statute mile. (Refer to AIM)
CONTAMINATED RUNWAY
A runway is considered contaminated whenever standing water,
ice, snow, slush, frost in any form, heavy rubber other substances are
present. A runway is contaminated with respect to rubber deposits or other
friction-degrading substances when the average friction value for any 500-foot
segment of the runway within the ALD fails below the recommended minimum
friction level and the average friction value in the adjacent 500-foot
segments fails below the maintenance planning friction level.
Conterminous U.S. -
The 48 adjoining States and the District of Columbia.
Continental United States -
The 49 States located on the continent of North America and the
District of Columbia.
[ICAO] Control Area -
A controlled airspace extending upwards from a specified limit
above the earth.
Controlled Airspace -
An airspace of defined dimensions within which air traffic control
service is provided to IFR flights and to VFR flights in accordance with
the airspace classification.
Note 1 - Controlled airspace is a generic term that covers Class
A, Class B, Class C, Class D, and Class E airspace.
Note 2 - Controlled airspace is also that airspace within which
all aircraft operators are subject to certain pilot qualifications, operating
rules, and equipment requirements in FAR Part 91 (for specific operating
requirements, please refer to FAR Part 91). For IFR operations in any class
of controlled airspace, a pilot must file an IFR flight plan and receive
an appropriate ATC clearance. Each Class B, Class C, and Class D airspace
area designated for an airport contains at least one primary airport around
which the airspace is designated (for specific designations and descriptions
of the airspace classes, please refer to FAR Part 71).
Controlled airspace in the United States is designated as follows:
1. CLASS A: Generally, that airspace from 18,000 feet MSL up
to and including FL 600, including the airspace overlying the waters within
12 nautical miles of the coast of the 48 contiguous States and Alaska.
Unless otherwise authorized, all persons must operate their aircraft under
IFR.
2. CLASS B: Generally, that airspace from the surface to 10,000
feet MSL surrounding the nation's busiest airports in terms of airport
operations or passenger enplanements. The configuration of each Class B
airspace area is individually tailored and consists of a surface area and
two or more layers (some Class B airspace areas resemble upside down wedding
cakes), and is designed to contain all published instrument procedures
once an aircraft enters the airspace. An ATC clearance is required for
all aircraft to operate in the area, and all aircraft that are so cleared
receive separation services within the airspace. The cloud clearance requirement
for VFR operations is "clear of clouds."
3. CLASS C: Generally, that airspace from the surface to 4,000
feet above the airport elevation (charted in MSL) surrounding those airports
that have an operational control tower, are serviced by a radar approach
control, and that have a certain number of IFR operations or passenger
enplanements. Although the configuration of each Class C area is individually
tailored, the airspace usually consists of a surface area with a 5 nautical
mile (NM) radius, an outer circle with a 10 nm radius that extends from
1,200 feet to 4,000 feet above the airport elevation and an outer area.
Each person must establish two-way radio communications with the ATC facility
providing air traffic services prior to entering the airspace and thereafter
maintain those communications while within the airspace. VFR aircraft are
only separated from IFR aircraft within the airspace.
4. CLASS D: Generally, that airspace from the surface to 2,500
feet above the airport elevation (charted in MSL) surrounding those airports
that have an operational control tower. The configuration of each Class
D airspace area is individually tailored and when instrument procedures
are published, the airspace will normally be designed to contain the procedures.
Arrival extensions for instrument approach procedures may be Class D or
Class E airspace. Unless otherwise authorized, each person must establish
two-way radio communications with the ATC facility providing air traffic
services prior to entering the airspace and thereafter maintain those communications
while in the airspace. No separation services are provided to VFR aircraft.
5. CLASS E: Generally, if the airspace is not Class A, Class
B, Class C, or Class D, and it is controlled airspace, it is Class E airspace.
Class E airspace extends upward from either the surface or a designated
altitude to the overlying or adjacent controlled airspace. When designated
as a surface area, the airspace will be configured to contain all instrument
procedures. Also in this class are Federal airways, airspace beginning
at either 700 or 1,200 feet AGL used to transition to/from the terminal
or enroute environment, enroute domestic, and offshore airspace areas designated
below 18,000 feet MSL. Unless designated at a lower altitude, Class E airspace
begins at 14,500 MSL over the United States, including that airspace overlying
the waters within 12 nautical miles of the coast of the 48 contiguous States
and Alaska, up to, but not including 18,000 feet MSL, and the airspace
above FL 600.
[ICAO] Controlled Airspace -
An airspace of defined dimensions within which air traffic control
service is provided to IFR flights and to VFR flights in accordance with
the airspace classification. Note - Controlled airspace is a generic term
which covers ATS airspace Classes A, B, C, D, and E.
Controlled Departure Time Programs -
These programs are the flow control process whereby aircraft
are held on the ground at the departure airport when delays are projected
to occur in either the enroute system or the terminal of intended landing.
The purpose of these programs is to reduce congestion in the air traffic
system or to limit the duration of airborne holding in the arrival center
or terminal area. A CDT is a specific departure slot shown on the flight
plan as an expected departure clearance time (EDCT).
Controlled Time of Arrival (CTA) -
The original estimated time of arrival adjusted by the ATCSCC
ground delay factor.
Controller - (See Air Traffic Control Specialist)
[ICAO] Controller -
A person authorized to provide air traffic control services.
Control Sector -
An airspace area of defined horizontal and vertical dimensions
for which a controller or group of controllers has air traffic control
responsibility normally within an air route traffic control center or an
approach control facility. Sectors are established based on predominant
traffic flows, altitude strata, and controller workload. Pilot communications
during operations within a sector are normally maintained on discrete frequencies
assigned to the sector. (See Discrete Frequency)
Control Slash -
A radar beacon slash representing the actual position of the
associated aircraft. Normally, the control slash is the one closest to
the interrogating radar beacon site. When ARTCC radar is operating in narrow
band (digitized) mode, the control slash is converted to a target symbol.
CONVECTIVE SIGMET -
A weather advisory concerning convective weather significant
to the safety of all aircraft. Convective SIGMETs are issued for tornadoes,
lines of thunderstorms, embedded thunderstorms of any intensity level,
areas of thunderstorms greater than or equal to VIP level 4 with an area
coverage of 4/10 (40%) or more, and hail 3/4 inch or greater. (See AWW,
SIGMET, CWA, and AIRMET) (Refer to AIM)
Convective Significant Meteorological Information - (See Convective SIGMET)
Coordinates -
The intersection of lines of reference, usually expressed in
degrees/minutes/seconds of latitude and longitude, used to determine position
or location.
Coordination Fix -
The fix in relation to which facilities will handoff, transfer
control of an aircraft, or coordinate flight progress data. For terminal
facilities, it may also serve as a clearance for arriving aircraft.
Copter - (See Helicopter)
Correction -
An error has been made in the transmission and the correct version
follows.
Coupled Approach -
A coupled approach is an instrument approach performed by the
aircraft autopilot which is receiving position information and/or steering
commands from on board navigation equipment. In general, coupled nonprecision
approaches must be discontinued and flown manually at altitudes lower than
50 feet below the minimum descent altitude, and coupled precision approaches
must be flown manually below 50 feet AGL. (See Autoland Approach).
Note: Coupled and autoland approaches are flown in VFR
and IFR. It is common for carriers to require their crews to fly coupled
approaches and autoland approaches (if certified) when the weather conditions
are less than approximately 4,000 RVR.
Course -
1. The intended direction of flight in the horizontal plane measured
in degrees from north.
2. The ILS localizer signal pattern usually specified as the
front course or the back course.
3. The intended track along a straight, curved, or segmented
MLS path.
(See Bearing, Radial, Instrument Landing System, Microwave Landing
System)
[ICAO] CPL - (See Current Flight Plan)
Critical Engine -
The engine which, upon failure, would most adversely affect the
performance or handling qualities of an aircraft.
CROSS (FIX) AT (ALTITUDE) -
Used by ATC when a specific altitude restriction at a specified
fix is required.
CROSS (FIX) AT OR ABOVE (ALTITUDE) -
Used by ATC when an altitude restriction at a specified fix is
required. It does not prohibit the aircraft from crossing the fix at a
higher altitude than specified; however, the higher altitude may not be
one that will violate a succeeding altitude restriction or altitude assignment.
(See Altitude Restriction) (Refer to AIM)
CROSS (FIX) AT OR BELOW (ALTITUDE) -
Used by ATC when a maximum crossing altitude at a specific fix
is required. It does not prohibit the aircraft from crossing the fix at
a lower altitude; however, it must be at or above the minimum IFR altitude.
(See Minimum IFR Altitude, Altitude Restriction) (Refer to FAR Part 91)
Crosswind -
1. When used concerning the traffic pattern, the word means "crosswind
leg." (See Traffic Pattern)
2. When used concerning wind conditions, the word means a wind
not parallel to the runway or the path of an aircraft. (See Crosswind Component)
Crosswind Component -
The wind component measured in knots at 90 degrees to the longitudinal
axis of the runway.
CRUISE -
Used in an ATC clearance to authorize a pilot to conduct flight
at any altitude from the minimum IFR altitude up to and including the altitude
specified in the clearance. The pilot may level off at any intermediate
altitude within this block of airspace. Climb/descent within the block
is to be made at the discretion of the pilot. However, once the pilot starts
descent and verbally reports leaving an altitude in the block, he may not
return to that altitude without additional ATC clearance. Further, it is
approval for the pilot to proceed to and make an approach at destination
airport and can be used in conjunction with:
1. An airport clearance limit at locations with a standard/special
instrument approach procedure. The FARs require that if an instrument letdown
to an airport is necessary, the pilot shall make the letdown in accordance
with a standard/special instrument approach procedure for that airport.
or
2. An airport clearance limit at locations that are within/below/outside
controlled airspace and without a standard/special instrument approach
procedure. Such a clearance is NOT AUTHORIZATION for the pilot to descend
under IFR conditions below the applicable minimum IFR altitude nor does
it imply that ATC is exercising control over aircraft in Class G airspace;
however, it provides a means for the aircraft to proceed to destination
airport, descend, and land in accordance with applicable FARs governing
VFR flight operations. Also, this provides search and rescue protection
until such time as the IFR flight plan is closed. (See Instrument Approach
Procedure)
Cruising Altitude -
An altitude or flight level maintained during enroute level flight.
This is a constant altitude and should not be confused with a cruise clearance.
(See Altitude) (See [ICAO] Cruising Level)
[ICAO] Cruising Level -
A level maintained during a significant portion of a flight.
Cruise Climb -
A climb technique employed by aircraft, usually at a constant
power setting, resulting in an increase of altitude as the aircraft weight
decreases.
Cruising Level - (See Cruising Altitude)
CT Message -
An EDCT time generated by the ATCSCC to regulate traffic at arrival
airports. Normally, a CT message is automatically transferred from the
Traffic Management System computer to the NAS enroute computer and appears
as an EDCT. In the event of a communication failure between the TMS and
the NAS, the CT message can be manually entered by the TMC at the enroute
facility.
CTA - (See Controlled Time of Arrival (CTA))
CTA - (See [ICAO] Control Area).
CTAF - (See Common Traffic Advisory Frequency)
[ICAO] Current Flight Plan (CPL) -
The flight plan, including changes, if any, brought about by
subsequent clearances.
CVFP Approach - (See Charted Visual Flight Procedure Approach)
CWA - (See Center Weather Advisory) (See Weather Advisory)
D
[ICAO] DA -
(See [ICAO] Decision Altitude/Decision Height)
DAIR - (See Direct Altitude And Identity Readout)
[ICAO] DANGER AREA -
An airspace of defined dimensions within which activities dangerous
to the flight of aircraft may exist at specified times.
Note: The term "Danger Area" is not used in reference
to areas within the United States or any of its possessions or territories.
Data Block - (See Alphanumeric Display)
Dead Reckoning -
Dead reckoning, as applied to flying, is the navigation of an
airplane solely by means of computations based on airspeed, course, heading,
wind direction, and speed, ground speed, and elapsed time.
[ICAO] Decision Altitude/Decision Height -
A specified altitude or height (A/H) in the precision approach
at which a missed approach must be initiated if the required visual reference
to continue the approach has not been established.
Note 1: Decision altitude (DA) is referenced to mean sea
level (MSL) and decision height (DH) is referenced to the threshold elevation.
Note 2: The required visual reference means that section
of the visual aids or of the approach area which should have been in view
for sufficient time for the pilot to have made an assessment of the aircraft
position and rate of change of position, in relation to the desired flight
path.
Decision Height (DH) -
With respect to the operation of aircraft, means the height at
which a decision must be made during an ILS, MLS, or PAR instrument approach
to either continue the approach or to execute a missed approach. (See [ICAO]
Decision Altitude/Decision Height)
Decoder -
The device used to decipher signals received from ATCRBS transponders
to effect their display as select codes. (See Codes, Radar)
Defense Visual Flight Rules (DVFR) -
Rules applicable to flights within an ADIZ conducted under the
visual flight rules in FAR Part 91. (See Air Defense Identification Zone)
(Refer to FAR Parts 91 and 99)
Delay Indefinite (Reason If Known) Expect Further Clearance (Time) -
Used by ATC to inform a pilot when an accurate estimate of the
delay time and the reason for the delay cannot immediately be determined;
e.g., a disabled aircraft on the runway, terminal or center area saturation,
weather below landing minimums, etc. (See Expect Further Clearance (Time))
Delay Time (DT) -
The amount of time that the arrival must lose to cross the meter
fix at the assigned meter fix time. This is the difference between ACLT
and VTA.
Departure Center -
The ARTCC having jurisdiction for the airspace that generates
a flight to the impacted airport.
Departure Control -
A function of an approach control facility providing air traffic
control service for departing IFR and, under certain conditions, VFR aircraft.
(See Approach Control Facility) (Refer to AIM)
Departure Sequencing Program (DSP) -
A program designed to assist in achieving a specified interval
over a common point for departures.
Departure Time -
The time an aircraft become airborne.
Descent Speed Adjustments -
Speed deceleration calculations made to determine an accurate
VTA. These calculations start at the transition point and use arrival speed
segments to the vertex.
Desired Course -
a. True - A predetermined desired course direction to be followed
(measured in degrees from true north).
b. Magnetic - A predetermined desired course direction to be
followed (measured in degrees from local magnetic north).
Desired Track -
The planned or intended track between two waypoints. It is measured
in degrees from either magnetic or true north. The instantaneous angle
may change from point to point along the great circle track between waypoints.
[ICAO] DETRESFA (Distress Phase) -
The code word used to designate an emergency phase wherein there
is reasonable certainty that an aircraft and its occupants are threatened
by grave and imminent danger or require immediate assistance.
Deviations -
1. A departure from a current clearance, such as an off course
maneuver to avoid weather or turbulence.
2. Where specifically authorized in the FARs and requested by
the pilot, ATC may permit pilots to deviate from certain regulations. (Refer
to AIM)
DF - (See Direction Finder)
DF Approach Procedure -
Used under emergency conditions where another instrument approach
procedure cannot be executed. DF guidance from an instrument approach is
given by ATC facilities with DF capability. (See DF Guidance, Direction
Finder) (Refer to AIM)
DF Fix -
The geographical location of an aircraft obtained by one or more
direction finders. (See Direction Finder)
DF Guidance -
Headings provided to aircraft by facilities equipped with direction
finding equipment. These headings, if followed, will lead the aircraft
to a predetermined point such as the DF station or an airport. DF guidance
is given to aircraft in distress or to other aircraft which request the
service. Practice DF guidance is provided when workload permits. (See Direction
Finder, DF Fix) (Refer to AIM)
DF Steer - (See DF Guidance)
DH - (See Decision Height)
[ICAO] DH - (See [ICAO] Decision Altitude/Decision Height)
DIRECT -
Straight line flight between two navigational aids, fixes, points,
or any combination thereof. When used by pilots in describing off airway
routes, points defining direct route segments become compulsory reporting
points unless the aircraft is under radar contact.
Direct Altitude And Identity Readout (DAIR) -
The DAIR System is a modification to the AN/TPX-42 Interrogator
System. The Navy has two adaptations of the DAIR System - Carrier Air Traffic
Control Direct Altitude and Identification Readout System for Aircraft
Carriers and Radar Air Traffic Control Facility Direct Altitude and Identify
Readout System for land based terminal operations. The DAIR detects, tracks,
and predicts secondary radar aircraft targets. Targets are displayed by
means of computer generated symbols and alphanumeric characters depicting
flight identification, altitude, ground speed, and flight plan data. The
DAIR System is capable of interfacing with ARTCCs.
Direction Finder -
A radio receiver equipped with a directional sensing antenna
used to take bearings on a radio transmitter. Specialized radio direction
finders are used in aircraft as air navigation aids. Others are ground
based, primarily to obtain a "fix" on a pilot requesting orientation assistance
or to locate downed aircraft. A location "fix" is established by the intersection
of two or more bearing lines plotted on a navigational chart using either
two separately located Direction Finders to obtain a fix on an aircraft
or by a pilot plotting the bearing indications of his DF on two separately
located ground based transmitters, both of which can be identified on his
chart. UDFs receive signals in the ultra high frequency radio broadcast
band; VDFs in the very high frequency band; and UVDFs in both bands. ATC
provides DF service at those air traffic control towers and flight service
stations listed in the Airport/Facility Directory and the DOD FLIP IFR
Enroute Supplement. (See DF Guidance, DF Fix)
Discrete Beacon Code - (See Discrete Code)
Discrete Code -
As used in the Air Traffic Control Radar Beacon System (ATCRBS),
any one of the 4096 selectable Mode 3/A aircraft transponder codes except
those ending in zero zero; e.g., discrete codes: 0010, 1201, 2317, 7777;
nondiscrete codes: 0100, 1200, 7700. Nondiscrete codes are normally reserved
for radar facilities that are not equipped with discrete decoding capability
and for other purposes such as emergencies (7700), VFR aircraft (1200),
etc. (See Radar) (Refer to AIM)
Discrete Frequency -
A separate radio frequency for use in direct pilot/controller
communications in air traffic control which reduces frequency congestion
by controlling the number of aircraft operating on a particular frequency
at one time. Discrete frequencies are normally designated for each control
sector in enroute/terminal ATC facilities. Discrete frequencies are listed
in the Airport/Facility Directory and the DOD FLIP IFR Enroute Supplement.
(See Control Sector)
Displaced Threshold -
A threshold that is located at a point on the runway other than
the designated beginning of the runway. (See Threshold) (Refer to AIM)
Distance (ALD) -
That portion of a runway available for Available Landing Distance
and roll-out for aircraft cleared for LAHSO. This distance is measured
from the landing threshold to the hold-short point.
Distance Measuring Equipment (DME) -
Equipment (airborne and ground) used to measure, in nautical
miles, the slant range distance of an aircraft from the DME navigational
aid. (See TACAN, VORTAC, Microwave Landing System)
Distress -
A condition of being threatened by serious and/or imminent danger
and of requiring immediate assistance.
Dive Brakes - (See Speed Brakes)
Diverse Vector Area (DVA) -
In a radar environment, that area in which a prescribed departure
route is not required as the only suitable route to avoid obstacles. The
area in which random radar vectors below the MVA/MIA, established in accordance
with the TERPS criteria for diverse departures obstacles and terrain avoidance,
may be issued to departing aircraft.
DME - (See Distance Measuring Equipment)
DME Fix -
A geographical position determined by reference to a navigational
aid which provides distance and azimuth information. It is defined by a
specific distance in nautical miles and a radial, azimuth, or course (i.e.
localizer) in degrees magnetic from that aid. (See Distance Measuring Equipment
(DME), Fix, Microwave Landing System)
DME Separation -
Spacing of aircraft in terms of distances (nautical miles) determined
by reference to distance measuring equipment (DME). (See Distance Measuring
Equipment)
DOD FLIP -
{New-98-3 Revised February 26, 1998}
Department of Defense Flight Information Publications used for
flight planning, en route, and terminal operations. FLIP is produced by
the National Imagery and Mapping Agency (NIMA) for world wide use. United
States Government Flight Information Publications (en route charts and
instrument approach procedure charts) are incorporated in DOD FLIP for
use in the National Airspace System (NAS).
Domestic Airspace -
Airspace which overlies the continental land mass of the United
States plus Hawaii and U.S. possessions. Domestic airspace extends to 12
miles offshore.
Downburst -
A strong downdraft which induces an outburst of damaging winds
on or near the ground. Damaging winds, either straight or curved, are highly
divergent. The sizes of downbursts vary from 1/2 mile or less to more than
10 miles. An intense down burst often causes widespread damage. Damaging
winds, lasting 5 to 30 minutes, could reach speeds as high as 120 knots.
Downwind Leg - (See Traffic Pattern)
Drag Chute -
A parachute device installed on certain aircraft which is deployed
on landing roll to assist in deceleration of the aircraft.
DSP - (See Departure Sequencing Program)
DT - (See Delay Time)
Due Regard -
A phase of flight wherein an aircraft commander of a State operated
aircraft assumes responsibility to separate his aircraft from all other
aircraft. (See also FAA Order 7110.65, Chapter 1, Word Meanings).
Duty Runway - (See Runway in Use/Active Runway/Duty Runway)
DVA - (See Diverse Vector Area)
DVFR - (See Defense Visual Flight Rules)
DVFR Flight Plan -
A flight plan filed for a VFR aircraft which intends to operate
in airspace within which the ready identification, location, and control
of aircraft are required in the interest of national security.
Dynamic -
Continuous review, evaluation, and change to meet demands.
Dynamic Restrictions -
Those restrictions imposed by the local facility on an "as needed"
basis to manage unpredictable fluctuations in traffic demands.
E
EARTS - (See Enroute Automated Radar Tracking System)
EDCT - (See Expected Departure Clearance Time)
EFC - (See Expect Further Clearance (Time))
ELT - (See Emergency Locator Transmitter)
EMERGENCY -
A distress or an urgency condition.
Emergency Locator Transmitter (ELT) -
A radio transmitter attached to the aircraft structure which
operates from its own power source on 121.5 MHz and 243.0 MHz. It aids
in locating downed aircraft by radiating a downward sweeping audio tone,
2 to 4 times per second. It is designed to function without human action
after an accident. (Refer to FAR 91.3, AIM)
E-MSAW - (See Enroute Minimum Safe Altitude Warning)
Engineered Performance Standards (EPS) -
A mathematically derived runway capacity standard. EPSs are calculated
for each airport on an individual basis and reflect that airport's aircraft
mix, operating procedures, runway layout, and specific weather conditions.
EPSs do not give consideration to staffing, experience levels, equipment
outages, and in-trail restrictions as does the AAR.
Enroute Air Traffic Control Services -
Air traffic control service provided aircraft on IFR flight plans,
generally by centers, when these aircraft are operating between departure
and destination terminal areas. When equipment, capabilities, and controller
workload permit, certain advisory/assistance services may be provided to
VFR aircraft. (See NAS Stage A, Air Route Traffic Control Center) (Refer
to AIM)
Enroute Automated Radar Tracking System (EARTS) -
An automated radar and radar beacon tracking system. Its functional
capabilities and design are essentially the same as the terminal ARTS IIIA
system except for the EARTS capability of employing both short range (ASR)
and long range (ARSR) radars, use of full digital radar displays, and fail-safe
design. (See Automated Radar Terminal Systems)
Enroute Charts - (See Aeronautical Charts)
Enroute Descent -
Descent from the enroute cruising altitude which takes place
along the route of flight.
Enroute Flight Advisory Service -
A service specifically designed to provide, upon pilot request,
timely weather information pertinent to his type of flight, intended route
of flight, and altitude. The FSSs providing this service are listed in
the Airport/Facility Directory. (See Flight Watch) (Refer to AIM)
Enroute High Altitude Charts -
(See Aeronautical Chart)
Enroute Low Altitude Charts -
(See Aeronautical Chart)
Enroute Minimum Safe Altitude Warning (E-MSAW) -
A function of the NAS Stage A enroute computer that aids the
controller by alerting him when a tracked aircraft is below or predicted
by the computer to go below a predetermined minimum IFR altitude (MIA)
Enroute Spacing Program (ESP) -
A program designed to assist the exit sector in achieving the
required in-trail spacing.
EPS - (See Engineered Performance Standards (EPS))
ESP - (See Enroute Spacing Program (ESP))
ESTABLISHED -
To be stable or fixed on a route, route segment, altitude, heading,
etc.
[ICAO] Estimated Elapsed Time -
The estimated time required to proceed from one significant point
to another. (See [ICAO] Total Estimated Elapsed Time)
[ICAO] Estimated Off Block Time -
The estimated time at which the aircraft will commence movement
associated with departure.
Estimated Time of Arrival (ETA) -
The time the flight is estimated to arrive at the gate (scheduled
operators) or the actual runway on times for nonscheduled operators.
Estimated Time Enroute (ETE) -
The estimated flying time from departure point to destination
(liftoff to touchdown).
ETA - (See Estimated Time of Arrival)
ETE - (See Estimated Time Enroute)
EXECUTE MISSED APPROACH -
Instructions issued to a pilot making an instrument approach
which means continue inbound to the missed approach point and execute the
missed approach procedure as described on the Instrument Approach Procedure
Chart or as previously assigned by ATC. The pilot may climb immediately
to the altitude specified in the missed approach procedure upon making
a missed approach. No turns should be initiated prior to reaching the missed
approach point. When conducting an ASR or PAR approach, execute the assigned
missed approach procedure immediately upon receiving instructions to "execute
missed approach." (Refer to AIM)
EXPECT (ALTITUDE) AT (TIME) or (FIX) -
Used under certain conditions to provide a pilot with an altitude
to be used in the event of two-way communications failure. It also provides
altitude information to assist the pilot in planning. (Refer to AIM)
Expected Departure Clearance Time (EDCT) -
The runway release time assigned to an aircraft in controlled
departure time programs and shown on the flight progress strip as an EDCT.
EXPECT FURTHER CLEARANCE (TIME) (EFC) -
The time a pilot can expect to receive clearance beyond a clearance
limit.
EXPECT FURTHER CLEARANCE VIA (AIRWAYS, ROUTES OR FIXES) -
Used to inform a pilot of the routing he can expect if any part
of the route beyond a short range clearance limit differs from that filed.
EXPEDITE -
Used by ATC when prompt compliance is required to avoid the development
of an imminent situation.
F
FAF - (See Final Approach Fix)
Fast File -
A system whereby a pilot files a flight plan via telephone that
is tape recorded and then transcribed for transmission to the appropriate
air traffic facility. Locations having a fast file capability are contained
in the Airport/Facility Directory. (Refer to AIM)
{New-98-3 Revised February 26, 1998}
FAWP -
Final Approach Waypoint
FCLT - (See Freeze Calculated Landing Time)
Feathered Propeller -
A propeller whose blades have been rotated so that the leading
and trailing edges are nearly parallel with the aircraft flight path to
stop or minimize drag and engine rotation. Normally used to indicate shutdown
of a reciprocating or turboprop engine due to malfunction.
Federal Airways - (See Low Altitude Airway Structure)
Feeder Fix -
The fix depicted on Instrument Approach Procedure Charts which
establishes the staring point of the feeder route.
Feeder Route -
A route depicted on instrument approach procedure charts to designate
routes for aircraft to proceed from the enroute structure to the initial
approach fix (IAF). (See Instrument Approach Procedure)
Ferry Flight -
A flight for the purpose of:
1. Returning an aircraft to base.
2. Delivering an aircraft from one location to another.
3. Moving an aircraft to and from a maintenance base.
Ferry flights, under certain conditions, may be conducted under
terms of a special flight permit.
Field Elevation - (See Airport Elevation)
Filed -
Normally used in conjunction with flight plans, meaning a flight
plan has been submitted to ATC.
Filed Enroute Delay -
Any of the following preplanned delays at points/areas along
the route of flight which require special flight plan filing and handling
techniques.
1. Terminal Area Delay - A delay within a terminal area for
touch and go, low approach, or other terminal area activity.
2. Special Use Airspace Delay - A delay within a Military Operating
Area, Restricted Area, Warning Area, or ATC Assigned Airspace.
3. Aerial Refueling Delay - A delay within an Aerial Refueling
Track or Anchor.
Filed Flight Plan -
The flight plan as filed with an ATS unit by the pilot or his
designated representative without any subsequent changes or clearances.
FINAL -
Commonly used to mean that an aircraft is on the final approach
course or is aligned with a landing area. (See Final Approach Course, Final
Approach - IFR, Traffic Pattern, Segments of an Instrument Approach Procedure)
[ICAO] Final Approach -
The part of an instrument approach procedure which commences
at the specified final approach fix, or point, or where such a fix or point
is not specified.
a) At the end of the last procedure turn, base turn, or inbound
turn of a racetrack procedure, if specified; or
b) At the point of interception of the last track specified in
the approach procedure; and ends at a point in the vicinity of an aerodrome
from which:
1) A landing can be made; or
2) A missed approach procedure is initiated.
Final Approach Course -
{New-98-3 Revised February 26, 1998}
A bearing/radial/track of an instrument approach leading to a
runway or an extended runway centerline all without regard to distance.
Final Approach Fix (FAF) -
The fix from which the final approach (IFR) to an airport is
executed and which identifies the beginning of the final approach segment.
It is designated on Government charts by the Maltese Cross symbol for nonprecision
approaches and the lightning bolt symbol for precision approaches; or when
ATC directs a lower than published Glideslope/Path Intercept Altitude,
it is the resultant actual point of the glideslope/path intercept. (See
Final Approach Point, Glideslope Intercept Altitude, Segments of an Instrument
Approach Procedure)
Final Approach - IFR -
The flight path of an aircraft which is inbound to an airport
on a final instrument approach course, beginning at the final approach
fix or point and extending to the airport or the point where a circle-to-land
maneuver or a missed approach is executed. (See Segments of an Instrument
Approach Procedure, Final Approach Fix, Final Approach Course, Final Approach
Point) (See [ICAO] Final Approach)
Final Approach Point (FAP) -
The point, applicable only to a nonprecision approach with no
depicted FAF (such as an on-airport VOR), where the aircraft is established
inbound on the final approach course from the procedure turn and where
the final approach descent may be commenced. The FAP serves as the FAF
and identifies the beginning of the final approach segment. (See Final
Approach Fix, Segments of an Instrument Approach Procedure)
Final Approach Segment - (See Segments of an Instrument Approach Procedure)
[ICAO] Final Approach Segment -
That segment of an instrument approach procedure in which alignment
and descent for landing are accomplished.
Final Controller -
The controller providing information and final approach guidance
during PAR and ASR approaches utilizing radar equipment. (See Radar Approach)
Final Monitor Aid (FMA) -
A high resolution color display that is equipped with the controller
alert system hardware/software which is used in the precision runway monitor
(PRM) system. The display includes alert algorithms providing the target
predictors, a color change alert when a target penetrates or is predicted
to penetrate the no transgression zone (NTZ), a color change alert if the
aircraft transponder becomes inoperative, synthesized voice alerts, digital
mapping, and like features contained in the PRM system. (See Radar Approach)
FINAL MONITOR CONTROLLER -
Air Traffic Control Specialist assigned to radar monitor the
flight path of aircraft during simultaneous parallel and simultaneous close
parallel ILS approach operations. Each runway is assigned a final monitor
controller during simultaneous parallel and simultaneous close parallel
ILS approaches. Final monitor controllers shall utilize the Precision Runway
Monitor (PRM) system during simultaneous close parallel ILS approaches.
FIR - (See Flight Information Region)
First Tier Center -
The ARTCC immediately adjacent to the impacted center.
Fix -
A geographical position determined by visual reference to the
surface, by reference to one or more radio NAVAIDs, by celestial plotting,
or by another navigational device.
Fix Balancing -
A process whereby aircraft are evenly distributed over several
available arrival fixes reducing delays and controller workload.
Flag -
A warning device incorporated in certain airborne navigation
and flight instruments indicating that:
1. Instruments are inoperative or otherwise not operating satisfactorily,
or
2. Signal strength or quality of the received signal falls below
acceptable values.
Flag Alarm - (See Flag)
Flameout -
An emergency condition caused by a loss of engine power.
Flameout Pattern -
An approach normally conducted by a single-engine military aircraft
experiencing loss or anticipating loss of engine power or control. The
standard overhead approach starts at a relatively high altitude over a
runway ("high key") followed by a continuous 180 degree turn to a high,
wide position ("low key") followed by a continuous 180 degree turn final.
The standard straight-in pattern starts at a point that results in a straight-in
approach with a high rate of descent to the runway. Flameout approaches
terminate in the type approach requested by the pilot (normally fullstop).
Flight Check -
A call sign prefix used by FAA aircraft engaged in flight inspection/certification
of navigational aids and flight procedures. The word "recorded" may be
added as a suffix; e.g., "Flight Check 320 recorded" to indicate that an
automated flight inspection is in progress in terminal areas. (See Flight
Inspection) (Refer to AIM)
Flight Following - (See Traffic Advisories)
Flight Information Region (FIR) -
An airspace of defined dimensions within which Flight Information
Service and Alerting Service are provided.
1. Flight Information Service - A service provided for the purpose
of giving advice and information useful for the safe and efficient conduct
of flights.
2. Alerting Service - A service provided to notify appropriate
organizations regarding aircraft in need of search and rescue aid and to
assist such organizations as required.
Flight Information Service -
A service provided for the purpose of giving advise and information
useful for the safe and efficient conduct of flights.
Flight Inspection -
In-flight investigation and evaluation of a navigational aid
to determine whether it meets established tolerances. (See Navigational
Aid) (See Flight Check)
FLIGHT LEVEL -
A level of constant atmospheric pressure related to a reference
datum of 29.92 inches of mercury. Each is stated in three digits that represent
hundreds of feet. For example, flight level 250 represents a barometric
altimeter indication of 25,000 feet; flight level 255, an indication of
25,500 feet. (See [ICAO] Flight Level)
[ICAO] Flight Level -
A surface of constant atmospheric pressure which is related to
a specific pressure datum, 1013.2 hPa (1013.2 mb), and is separated from
other such surfaces by specific pressure intervals.
Note 1: A pressure type altimeter calibrated in accordance
with the standard atmosphere:
a) When set to a QNH altimeter setting, will indicate
altitude;
b) When set to a QFE altimeter setting, will indicate
height above the QFE reference datum; and
c) When set to a pressure of 1013.2 hPa (1013.2 mb), may
be used to indicate flight levels.
Note 2: The terms height and altitude, used in Note 1
above, indicate altimetric rather than geometric heights and altitudes.
Flight Line -
A term used to describe the precise movement of a civil photogrammetric
aircraft along a predetermined course(s) at a predetermined altitude during
the actual photographic run.
Flight Management Systems -
A computer system that uses a large data base to allow routes
to be preprogrammed and fed into the system by means of a data loader.
The system is constantly updated with respect to position accuracy by reference
to conventional navigation aids. The sophisticated program and its associated
data base insures that the most appropriate aids are automatically selected
during the information update cycle.
Flight Management System Procedure -
An arrival, departure, or approach procedure developed for use
by aircraft with a slant (/) E or slant (/) F equipment suffix.
Flight Path -
A line, course, or track along which an aircraft is flying or
intended to be flown. (See Track, Course)
Flight Plan -
Specified information relating to the intended flight of an aircraft
that is filed orally or in writing with an FSS or an ATC facility. (See
Fast File, Filed) (Refer to AIM)
Flight Plan Area -
The geographical area assigned by regional air traffic divisions
to a flight service station for the purpose of search and rescue for VFR
aircraft, issuance of notams, pilot briefing, in-flight services, broadcast,
emergency services, flight data processing, international operations, and
aviation weather services. Three letter identifiers are assigned to every
flight service station and are annotated in AFDs and Order 7350.5 as tie-in
facilities. (See Fast File, Filed) (Refer to AIM)
Flight Recorder -
A general term applied to any instrument or device that records
information about the performance of an aircraft in flight or about conditions
encountered in flight. Flight recorders may make records of airspeed, outside
air temperature, vertical acceleration, engine RPM, manifold pressure,
and other pertinent variables for a given flight. (See [ICAO] Flight Recorder)
[ICAO] Flight Recorder -
Any type of recorder installed in the aircraft for the purpose
of complementing accident/incident investigation.
Note: See Annex 6, Part I, for specifications relating
to flight recorders.
Flight Service Station (FSS) -
Air traffic facilities which provide pilot briefing, enroute
communications and VFR search and rescue services, assist lost aircraft
and aircraft in emergency situations, relay ATC clearances, originate Notices
to Airmen, broadcast aviation weather and NAS information, receive and
process IFR flight plans, and monitor NAVAIDs. In addition, at selected
locations, FSSs provide Enroute Flight Advisory Service (Flight Watch),
take weather observations, issue airport advisories, and advise Customs
and Immigration of transborder flights. (Refer to AIM)
Flight Standards District Office (FSDO) -
An FAA field office serving an assigned geographical area and
staffed with Flight Standards personnel who serve the aviation industry
and the general public on matters relating to the certification and operation
of air carrier and general aviation aircraft. Activities include general
surveillance of operational safety, certification of airmen and aircraft,
accident prevention, investigation, enforcement, etc.
Flight Test -
A flight for the purpose of:
1. Investigating the operation/flight characteristics of an
aircraft or aircraft component.
2. Evaluating an applicant for a pilot certificate or rating.
Flight Visibility - (See Visibility)
Flight Watch -
A shortened term for use in air/ground contacts to identify the
flight service station providing Enroute Flight Advisory Service; e.g.,
"Oakland Flight Watch." (See Enroute Flight Advisory Service)
FLIP - (See DOD FLIP)
Flow Control -
Measures designed to adjust the flow of traffic into a given
airspace, along a given route, or bound for a given aerodrome (airport)
so as to ensure the most effective utilization of the airspace. (See Quota
Flow Control) (Refer to Airport/Facility Directory)
Fly-by Waypoint -
A fly-by waypoint requires the use of turn anticipation to avoid
overshoot of the next flight segment.
Fly Heading (Degrees) -
Informs the pilot of the heading he should fly. The pilot may
have to turn to, or continue on, a specific compass direction in order
to comply with the instructions. The pilot is expected to turn in the shorter
direction to the heading unless otherwise instructed by ATC.
Fly-over Waypoint -
A fly-over waypoint precludes any turn until the waypoint is
overflown and is followed by an intercept maneuver of the next flight segment.
FMA -
(See Final Monitor Aid)
FMS -
(See Flight Management System)
FMSP -
(See Flight Management System Procedure)
Formation Flight -
More than one aircraft which, by prior arrangement between the
pilots, operate as a single aircraft with regard to navigation and position
reporting. Separation between aircraft within the formation is the responsibility
of the flight leader and the pilots of the other aircraft in the flight.
This includes transition periods when aircraft within the formation are
maneuvering to attain separation from each other to effect individual control
and during join-up and breakaway.
1. A standard formation is one in which a proximity of no more
than 1 mile laterally or longitudinally and within 100 feet vertically
from the flight leader is maintained by each wingman.
2. Nonstandard formations are those operating under any of the
following conditions:
a. When the flight leader has requested and ATC has approved
other than standard formation dimensions.
b. When operating within an authorized altitude reservation
(ALTRV) or under the provisions of a letter of agreement.
c. When the operations are conducted in airspace specifically
designed for a special activity. (See Altitude Reservation) (Refer to FAR
Part 91)
FRC - (See Request Full Route Clearance)
Freeze/Frozen -
Terms used in referring to arrivals which have been assigned
ACLTs and to the lists in which they are displayed.
Freeze Calculated Landing Time (FCLT) -
A dynamic parameter number of minutes prior to the meter fix
calculated time of arrival for each aircraft when the TCLT is frozen and
becomes an ACLT (i.e., the VTA is updated and consequently the TCLT is
modified as appropriate until FCLT minutes prior to meter fix calculated
time of arrival, at which time updating is suspended and an ACLT and a
frozen meter fix crossing time (MFT) is assigned).
Freeze Speed Parameter (FSPD) -
A speed adapted for each aircraft to determine fast and slow
aircraft. Fast aircraft freeze on parameter FCLT and slow aircraft freeze
on parameter MLDI.
Friction Measurement -
A measurement of the friction characteristics of the runway pavement
surface using continuous self-watering friction measurement equipment in
accordance with the specifications, procedures and schedules contained
in AC 150/5320-12, Measurement, Construction, and Maintenance of Skid Resistant
Airport Pavement Surfaces.
FSDO - (See Flight Standards District Office)
FSPD - (See Freeze Speed Parameter)
FSS - (See Flight Service Station)
Fuel Dumping -
Airborne release of usable fuel. This does not include the dropping
of fuel tanks. (See Jettisoning of External Stores)
Fuel Remaining -
A phrase used by either pilots or controllers when relating to
the fuel remaining on board until actual fuel exhaustion. When transmitting
such information in response to either a controller question or pilot initiated
cautionary advisory to air traffic control, pilots will state the APPROXIMATE
NUMBER OF MINUTES the flight can continue with the fuel remaining. All
reserve fuel SHOULD BE INCLUDED in the time stated, as should an allowance
for established fuel gauge system error.
Fuel Siphoning -
Unintentional release of fuel caused by overflow, puncture, loose
cap, etc.
Fuel Venting - (See Fuel Siphoning)
G
GADO - (See General Aviation District Office)
Gate Hold Procedures -
Procedures at selected airports to hold aircraft at the gate
or other ground location whenever departure delays exceed or are anticipated
to exceed 15 minutes. The sequence for departure will be maintained in
accordance with initial call up unless modified by flow control restrictions.
Pilots should monitor the ground control/clearance delivery frequency for
engine start/taxi advisories or new proposed start/taxi time if the delay
changes. (See Flow Control)
GCA - (See Ground Controlled Approach)
General Aviation -
That portion of civil aviation which encompasses all facets of
aviation except air carriers holding a certificate of public convenience
and necessity from the Civil Aeronautics Board and large aircraft commercial
operators. (See [ICAO] General Aviation)
[ICAO] General Aviation -
All civil aviation operations other than scheduled air services
and nonscheduled air transport operations for remuneration or hire.
General Aviation District Office (GADO) -
An FAA field office serving a designated geographical area and
staffed with Flight Standards personnel who have the responsibility for
serving the aviation industry and the general public on all matters relating
to the certification and operation of general aviation aircraft.
Geo Map -
The digitized map markings associated with the ASR-9 Radar System
Glidepath - (See Glideslope)
Glidepath Intercept Altitude - (See Glideslope Intercept Altitude)
Glideslope -
Provides vertical guidance for aircraft during approach and landing.
The glideslope/glidepath is based on the following:
1. Electronic components emitting signals which provide vertical
guidance by reference to airborne instruments during instrument approaches
such as ILS/MLS, or
2. Visual ground aids, such as VASI, which provide vertical
guidance for a VFR approach or for the visual portion of an instrument
approach and landing.
3. PAR. Used by ATC to inform an aircraft making a PAR approach
of its vertical position (elevation) relative to the descent profile. (See
[ICAO] Glidepath)
[ICAO] Glidepath -
A descent profile determined for vertical guidance during a final
approach.
Glideslope Intercept Altitude -
The minimum altitude to intercept the glideslope/path on a precision
approach. The intersection of the published intercept altitude with the
glideslope path, designated on Government charts by the lightning bolt
symbol, is the precision FAF; however, when ATC directs a lower altitude,
the resultant lower intercept position is then the FAF. (See Final Approach
Fix, Segments of an Instrument Approach Procedure)
Global Positioning System (GPS) -
A space-base radio positioning, navigation, and time-transfer
system. The system provides highly accurate position and velocity information,
and precise time, on a continuous global basis, to an unlimited number
of properly equipped users. The system is unaffected by weather, and provides
a worldwide common grid reference system. The GPS concept is predicated
upon accurate and continuous knowledge of the spatial position of each
satellite in the system with respect to time and distance from a transmitting
satellite to the user. The GPS receiver automatically selects appropriate
signals from the satellites in view and translates these into three-dimensional
position, velocity, and time. System accuracy for civil users is normally
100 meters horizontally.
GO AHEAD -
Proceed with your message. Not to be used for any other purpose.
GO AROUND -
Instructions for a pilot to abandon his approach to landing.
Additional instructions may follow. Unless otherwise advised by ATC, a
VFR aircraft or an aircraft conducting visual approach should overfly the
runway while climbing to traffic pattern altitude and enter the traffic
pattern via the crosswind leg. A pilot on an IFR flight plan making an
instrument approach should execute the published missed approach procedure
or proceed as instructed by ATC; e.g., "Go around" (additional instructions
if required). (See Low Approach, Missed Approach)
GPS -
(See Global Positioning System)
Ground Clutter -
A pattern produced on the radar scope by ground returns which
may degrade other radar returns in the affected area. The effect of ground
clutter is minimized by the use of moving target indicator (MTI) circuits
in the radar equipment resulting in a radar presentation which displays
only targets which are in motion. (See Clutter)
{New-98-8 Added August 13, 1998}
Ground Communication Outlet (GCO) -
An unstaffed, remotely controlled, ground/ground communications
facility. Pilots at uncontrolled airports may contact ATC and FSS via VHF
to a telephone connection to obtain an instrument clearance or close a
VFR or IFR flight plan. They may also get an updated weather briefing prior
to take-off. Pilots will use four "key clicks" on the VHF radio to contact
the appropriate ATC facility or six "key clicks" to contact the FSS. The
GCO system is intended to be used only on the ground.
Ground Controlled Approach (GCA) -
A radar approach system operated from the ground by air traffic
control personnel transmitting instructions to the pilot by radio. The
approach may be conducted with surveillance radar (ASR) only or with both
surveillance and precision approach radar (PAR). Usage of the term "GCA"
by pilots is discouraged except when referring to a GCA facility. Pilots
should specifically request a "PAR" approach when a precision radar approach
is desired or request an "ASR" or "surveillance" approach when a nonprecision
radar approach is desired. (See Radar Approach)
Ground Delay -
The amount of delay attributed to ATC, encountered prior to departure,
usually associated with a CDT program.
Ground Speed -
The speed of an aircraft relative to the surface of the earth.
Ground Stop -
Normally, the last initiative to be utilized; this method mandates
that the terminal facility will not allow any departures to enter the ARTCC
airspace until further notified.
Ground Visibility - (See Visibility)
H
HAA - (See Height Above Airport)
HAL - (See Height Above Landing)
Handoff -
An action taken to transfer the radar identification of an aircraft
from one controller to another if the aircraft will enter the receiving
controller's airspace and radio communications with the aircraft will be
transferred.
HAT - (See Height Above Touchdown)
HAVE NUMBERS -
Used by pilots to inform ATC that they have received runway,
wind, and altimeter information only.
Hazardous In-flight Weather Advisory Service (HIWAS) -
Continuous recorded hazardous in-flight weather forecasts broadcasted
to airborne pilots over selected VOR outlets defined as an HIWAS BROADCAST
AREA.
Hazardous Weather Information -
Summary of significant meteorological information (SIGMET/WS),
convective significant meteorological information (convective SIGMET/WST),
urgent pilot weather reports (urgent PIREP/UUA), center weather advisories
(CWA), airmen's meteorological information (AIRMET/WA) and any other weather
such as isolated thunderstorms that are rapidly developing and increasing
in intensity, or low ceilings and visibilities that are becoming widespread
which is considered significant and are not included in a current hazardous
weather advisory.
HEAVY (AIRCRAFT) - (See Aircraft Classes)
Height Above Airport (HAA) -
The height of the Minimum Descent Altitude above the published
airport elevation. This is published in conjunction with circling minimums.
(See Minimum Descent Altitude)
Height Above Landing (HAL) -
The height above a designated helicopter landing area used for
helicopter instrument approach procedures. (Refer to FAR Part 97)
Height Above Touchdown (HAT) -
The height of the Decision Height or Minimum Descent Altitude
above the highest runway elevation in the touchdown zone (first 3,000 feet
of the runway). HAT is published on instrument approach charts in conjunction
with all straight-in minimums. (See Decision Height, Minimum Descent Altitude)
Helicopter -
Rotorcraft that, for its horizontal motion, depends principally
on its engine driven rotors. (See [ICAO] Helicopter)
[ICAO] Helicopter -
A heavier than air aircraft supported in flight chiefly by the
reactions of the air on one or more power driven rotors on substantially
vertical axes.
Helipad -
A small, designated area, usually with a prepared surface, on
a heliport, airport, landing/takeoff area, apron/ramp, or movement area
used for takeoff, landing, or parking of helicopters.
Heliport -
An area of land, water, or structure used or intended to be used
for the landing and takeoff of helicopters and includes its buildings and
facilities if any.
Heliport Reference Point (HRP) -
The geographic center of a heliport.
Hertz (Hz) -
The standard radio equivalent of frequency in cycles per second
of an electromagnetic wave. Kilohertz (kHz) is a frequency of one thousand
cycles per second. Megahertz (MHz) is a frequency of one million cycles
per second.
HF - (See High Frequency)
HF Communications - (See High Frequency Communications)
High Frequency (HF) -
The frequency band between 3 and 30 MHz. (See High Frequency
Communications)
High Frequency Communications -
High radio frequencies (HF) between 3 and 30 MHz used for air-to-ground
voice communication in overseas operations.
High Speed Exit - (See High Speed Taxiway)
High Speed Taxiway -
A long radius taxiway designed and provided with lighting or
marking to define the path of aircraft, traveling at high speed (up to
60 knots), from the runway center to a point on the center of a taxiway.
Also referred to as long radius exit or turnoff taxiway. The high speed
taxiway is designed to expedite aircraft turning off the runway after landing,
thus reducing runway occupancy time.
High Speed Turnoff - (See High Speed Taxiway)
HIWAS - (See Hazardous In-flight Weather Advisory Service)
HIWAS AREA - (See Hazardous In-flight Weather Advisory Service Area)
HIWAS Broadcast Area -
A geographical area of responsibility including one or more HIWAS
outlet areas assigned to an AFSS/FSS for hazardous weather advisory broadcasting.
HIWAS Outlet Area -
An area defined as a 150 NM radius of a HIWAS outlet, expanded
as necessary to provide coverage.
Holding Procedure - (See Hold Procedure)
Hold Procedure -
A predetermined maneuver which keeps aircraft within a specified
airspace while awaiting further clearance from air traffic control. Also
used during ground operations to keep aircraft within a specified area
or at a specified point while awaiting further clearance from air traffic
control. (See Holding Fix) (Refer to AIM)
{New-98-3 Added February 26, 1998}
Hold-Short Point -
A point on the runway beyond which a landing aircraft with a
LAHSO clearance is not authorized to proceed. This point may be located
prior to an intersecting runway, taxiway, predetermined point, or approach/departure
flight path.
Holding Fix -
A specified fix identifiable to a pilot by NAVAIDs or visual
reference to the ground used as a reference point in establishing and maintaining
the position of an aircraft while holding. (See Fix, Visual Holding) (Refer
to AIM)
[ICAO] Holding Point -
A specified location, identified by visual or other means, in
the vicinity of which the position of an aircraft in flight is maintained
in accordance with air traffic control clearances.
Hold For Release -
Used by ATC to delay an aircraft for traffic management reasons;
i.e., weather, traffic volume, etc. Hold for release instructions (including
departure delay information) are used to inform a pilot or a controller
(either directly or through an authorized relay) that an IFR departure
clearance is not valid until a release time or additional instructions
have been received. (See [ICAO] Holding Point)
{New-98-3 Revised February 26, 1998}
Hold-Short Position Marking -
The painted runway marking located at the hold-short point on
all LAHSO runways.
Hold-Short Position Lights -
Flashing in-pavement white lights located at specified hold-short
points.
Hold-Short Position Signs -
{New-98-3 Revised February 26, 1998}
Red and White holding position signs located alongside the hold-short
point.
HOMING -
Flight toward a NAVAID, without correcting for wind, by adjusting
the aircraft heading to maintain a relative bearing of zero degrees. (See
Bearing) (See [ICAO] Homing)
[ICAO] HOMING -
The procedure of using the direction finding equipment of one
radio station with the emission of another radio station, where at least
one of the stations is mobile, and whereby the mobile station proceeds
continuously towards the other station.
Hover Check -
Used to describe when a helicopter/VTOL aircraft requires a stabilized
hover to conduct a performance/power check prior to hover taxi, air taxi,
or takeoff. Altitude of the hover will vary based on the purpose of the
check.
Hover Taxi -
Used to describe a helicopter/VTOL aircraft movement conducted
above the surface and in ground effect at airspeeds less than approximately
20 knots. The actual height may vary, and some helicopters may require
hover taxi above 25 feet AGL to reduce ground effect turbulence or provide
clearance for cargo sling loads. (See Air Taxi, Hover Check) (Refer to
AIM)
HOW DO YOU HEAR ME? -
A question relating to the quality of the transmission or to
determine how well the transmission is being received.
Hz - (See Hertz)
I
IAF - (See Initial Approach Fix)
IAP - (See Instrument Approach Procedure)
IAWP -
Initial Approach Waypoint
ICAO - (See International Civil Aviation Organization)
[ICAO] ICAO -
(See [ICAO] International Civil Aviation Organization)
Icing - The accumulation of airframe ice.
Types of icing are:
a. Rime Ice - Rough, milky, opaque ice formed by the instantaneous
freezing of small supercooled water droplets.
b. Clear Ice - A glossy, clear, or translucent ice formed by
the relatively slow freezing or large supercooled water droplets.
c. Mixed - A mixture of clear ice and rime ice.
Intensity of icing:
a. Trace - Ice becomes perceptible. Rate of accumulation is
slightly greater than the rate of sublimation. It is not hazardous even
though deicing/anti-icing equipment is not utilized unless encountered
for an extended period of time (over 1 hour).
b. Light - The rate of accumulation may create a problem if
flight is prolonged in this environment (over 1 hour). Occasional use of
deicing/anti-icing equipment removes/prevents accumulation. It does not
present a problem if the deicing\anti-icing equipment is used.
c. Moderate - The rate of accumulation is such that even short
encounters become potentially hazardous and use of deicing\anti-icing or
flight diversion is necessary.
d. Severe - The rate of accumulation is such that deicing\anti-icing
equipment fails to reduce or control the hazard. Immediate flight diversion
is necessary.
IDENT -
A request for a pilot to activate the aircraft transponder identification
feature. This will help the controller to confirm an aircraft identity
or to identify an aircraft. (Refer to AIM)
Ident Feature -
The special feature in the Air Traffic Control Radar Beacon System
(ATCRBS) equipment. It is used to immediately distinguish one displayed
beacon target from other beacon targets. (See Ident)
IF - (See Intermediate Fix)
IFIM - (See International Flight Information Manual)
IF NO TRANSMISSION RECEIVED FOR (TIME) -
Used by ATC in radar approaches to prefix procedures which should
be followed by the pilot in event of lost communications. (See Lost Communications)
IFR - (See Instrument Flight Rules)
IFR Aircraft -
An aircraft conducting flight in accordance with instrument flight
rules.
IFR Conditions -
Weather conditions below the minimum for flight under visual
flight rules. (See Instrument Meteorological Conditions)
IFR Departure Procedure - (See IFR Takeoff Minimums and Departure Procedures) (Refer to AIM)
IFR Flight - (See IFR Aircraft)
IFR Landing Minimums - (See Landing Minimums)
IFR Military Training Routes (IR) -
Routes used by the Department of Defense and associated Reserve
and Air Guard units for the purpose of conducting low altitude navigation
and tactical training in both IFR and VFR weather conditions below 10,000
feet MLS at airspeeds in excess of 250 knots IAS.
{New-98-8 Revised August 13, 1998. "DP" was "SID"}
IFR Takeoff Minimums and Departure Procedures -
Federal Aviation Regulations Part 91, prescribes standard takeoff
rules for certain civil users. At some airports, obstructions or other
factors require the establishment of nonstandard takeoff minimums, departure
procedures, or both to assist pilots in avoiding obstacles during climb
to the minimum enroute altitude. Those airports are listed in NOS/DOD Instrument
Approach Charts (IAPs) under a section entitled "IFR Takeoff Minimums and
Departure Procedures." The NOS/DOD IAP chart legend illustrates the symbol
used to alert the pilot to nonstandard takeoff minimums and departure procedures.
When departing IFR from such airports or from any airports where there
are no departure procedures, DP's, or ATC facilities available, pilots
should advise ATC of any departure limitations. Controllers may query a
pilot to determine acceptable departure directions, turns, or headings
after takeoff. Pilots should be familiar with the departure procedures
and must assure that their aircraft can meet or exceed any specified climb
gradients.
{New-98-3 Added February 26, 1998}
IF/IAWP -
Intermediate Fix/Initial Approach Waypoint. The waypoint where
the final approach course of a T approach meets the crossbar of the T.
When designated (in conjunction with a TAA) this waypoint will be used
as an IAWP when approaching the airport from certain directions, and as
an IFWP when beginning the approach from another IAWP.
IFWP -
Intermediate Fix Waypoint
ILS - (See Instrument Landing System)
ILS Categories -
1. ILS Category I - An ILS approach procedure which provides
for approach to a height above touchdown of not less than 200 feet and
with runway visual range of not less than 1,800 feet.
2. ILS Category II - An ILS approach procedure which provides
for approach to a height above touchdown of not less than 100 feet and
with runway visual range of not less than 1,200 feet.
3. ILS Category III.
a. IIIA - An ILS approach procedure which provides for approach
without a decision height minimum and with runway visual range of not less
than 700 feet.
b. IIIB - An ILS approach procedure which provides for approach
without a decision height minimum and with runway visual range of not less
than 150 feet.
c. IIIC - An ILS approach procedure which provides for approach
without a decision height minimum and without runway visual range minimum.
{New-98-3 Added February 26, 1998}
ILS PRM Approach -
An instrument landing system (ILS) approach conducted
to parallel runways whose extended centerlines are separated by less than
4,300 feet and the parallel runways have a Precision Runway Monitoring
(PRM) system that permits simultaneous independent ILS approaches.
IM - (See Inner Marker)
IMC - (See Instrument Meteorological Conditions)
IMMEDIATELY -
Used by ATC when such action compliance is required to avoid
an imminent situation.
[ICAO] INCERFA (Uncertainty Phase) -
The code word used to designate an emergency phase wherein there
is concern about the safety of an aircraft or its occupants. In most cases
this phase involves an aircraft which is overdue or unreported.
INCREASE SPEED TO (SPEED) - (See Speed Adjustment)
Inertial Navigation System (INS) -
An RNAV system which is a form of self-contained navigation.
(See Area Navigation/RNAV)
In-flight Refueling - (See Aerial Refueling)
In-flight Weather Advisory - (See Weather Advisory)
Information Request (INREQ) -
A request originated by an FSS for information concerning an
overdue VFR aircraft.
Initial Approach Fix (IAF) -
The fixes depicted on instrument approach procedure charts that
identify the beginning of the initial approach segment(s). (See Fix, Segments
of an Instrument Approach Procedure)
Initial Approach Segment - (See Segments of an Instrument Approach Procedure)
[ICAO] Initial Approach Segment -
That segment of an instrument approach procedure between the
initial approach fix and the intermediate approach fix or, where applicable,
the final approach fix or point.
Inland Navigation Facility -
A navigation aid on a North American Route at which the common
route and/or the noncommon route begins or ends.
Inner Marker (IM) -
A marker beacon used with an ILS (CAT II) precision approach
located between the middle marker and the end of the ILS runway, transmitting
a radiation pattern keyed at six dots per second and indicating to the
pilot, both aurally and visually, that he is at the designated decision
height (DH), normally 100 feet above the touchdown zone elevation, on the
ILS CAT II approach. It also marks progress during a CAT III approach.
(See Instrument Landing System) (Refer to AIM)
Inner Marker Beacon - (See Inner Marker)
INREQ - (See Information Request)
INS - (See Inertial Navigation System)
Instrument Approach - (See Instrument Approach Procedure)
Instrument Approach Procedure (IAP) -
A series of predetermined maneuvers for the orderly transfer
of an aircraft under instrument flight conditions from the beginning of
the initial approach to a landing or to a point from which a landing may
be made visually. It is prescribed and approved for a specific airport
by competent authority. (See Segments of an Instrument Approach Procedure)
(Refer to FAR Part 91, AIM)
1. U.S. civil standard instrument approach procedures are approved
by the FAA as prescribed under FAR Part 97 and are available for public
use.
2. U.S. military standard instrument approach procedures are
approved and published by the Department of Defense.
3. Special instrument approach procedures are approved by the
FAA for individual operators but are not published in FAR Part 97 for public
use.
(See [ICAO] Instrument Approach Procedure)
[ICAO] Instrument Approach Procedure -
A series of predetermined maneuvers by reference to flight instruments
with specified protection from obstacles from the initial approach fix,
or where applicable, from the beginning of a defined arrival route to a
point from which a landing can be completed and thereafter, if a landing
is not completed, to a position at which holding or enroute obstacle clearance
criteria apply.
Instrument Approach Procedures Charts -
(See Aeronautical Chart)
{New-98-8 Added August 13, 1998}
Instrument Departure Procedure (DP) -
A preplanned instrument flight rule (IFR) air traffic control
departure procedure printed for pilot use in graphic and/or textual form.
DP's provide transition from the terminal to the appropriate en route structure.
(See IFR Takeoff Minimums and Departure Procedures.) (Refer to AIM.)
{New-98-8 Added August 13, 1998}
Instrument Departure Procedure (DP) Charts -
(See Aeronautical Chart.)
Instrument Flight Rules (IFR) -
Rules governing the procedures for conducting instrument flight.
Also a term used by pilots and controllers to indicate type of flight plan.
(See Visual Flight Rules, Instrument Meteorological Conditions, Visual
Meteorological Conditions) (Refer to AIM) (See [ICAO] Instrument Flight
Rules)
[ICAO] Instrument Flight Rules -
A set of rules governing the conduct of flight under instrument
meteorological conditions.
Instrument Landing System (ILS) -
A precision instrument approach system which normally consists
of the following electronic components and visual aids:
1. Localizer. (See Localizer)
2. Glideslope. (See Glideslope)
3. Outer Marker. (See Outer Marker)
4. Middle Marker. (See Middle Marker)
5. Approach Lights. (See Airport Lighting)
(Refer to FAR Part 91, AIM)
Instrument Meteorological Conditions (IMC) -
Meteorological conditions expressed in terms of visibility, distance
from cloud, and ceiling less than the minima specified for visual meteorological
conditions. (See Visual Meteorological Conditions, Instrument Flight Rules,
Visual Flight Rules)
Instrument Runway -
A runway equipped with electronic and visual navigation aids
for which a precision or nonprecision approach procedure having straight-in
landing minimums has been approved. (See [ICAO] Instrument Runway)
[ICAO] Instrument Runway -
One of the following types of runways intended for the operation
of aircraft using instrument approach procedures:
a) Nonprecision Approach Runway. An instrument runway served
by visual aids and nonvisual aid providing at least directional guidance
adequate for a straight-in approach.
b) Precision Approach Runway. Category I. An instrument runway
served by ILS and visual aids intended for operations down to 60 m (200
feet) decision height and down to an RVR of the order to 800 m.
c) Precision Approach Runway, Category II. An instrument runway
served by ILS and visual aids intended for operations down to 30 m (100
feet) decision height and down to an RVR of the order of 400 m.
d) Precision Approach Runway, Category III. An instrument runway
served by ILS to and along the surface of the runway and:
A - Intended for operations down to an RVR of the order
of 200 m (no decision height being applicable) using visual aids during
the final phase of landing;
B - Intended for operations down to an RVR of the order
of 50 m (no decision height being applicable) using visual aids for taxiing;
C - Intended for operations without reliance on visual
reference for landing or taxiing.
Note 1: See Annex 10, Volume I, Part I Chapter 3, for
related ILS specifications.
Note 2: Visual aids need not necessarily be matched to
the scale of nonvisual aids provided. The criterion for the selection of
visual aids is the conditions in which operations are intended to be conducted.
Integrity -
The ability of a system to provide timely warnings to users when
the system should not be used for navigation.
Intermediate Approach Segment - (See Segments of an Instrument Approach Procedure)
[ICAO] Intermediate Approach Segment -
That segment of an instrument approach procedure between either
the intermediate approach fix and the final approach fix or point, or between
the end of a reversal, race track or dead reckoning track procedure and
the final approach fix or point, as appropriate.
Intermediate Fix (IF) -
The fix that identifies the beginning of the intermediate approach
segment of an instrument approach procedure. The fix is not normally identified
on the instrument approach chart as an intermediate fix (IF). (See Segments
of an Instrument Approach Procedure)
Intermediate Landing -
On the rare occasion that this option is requested, it should
be approved. The departure center, however, must advise the ATCSCC so that
the appropriate delay is carried over and assigned at the intermediate
airport. An intermediate landing airport within the arrival center will
not be accepted without coordination with and the approval of the ATCSCC.
International Airport -
Relating to international flight, it means:
1. An airport of entry which has been designated by the Secretary
of Treasury or Commissioner of Customs as an international airport for
customs service.
2. A landing rights airport at which specific permission to
land must be obtained from customs authorities in advance of contemplated
use.
3. Airports designated under the Convention on International
Civil Aviation as an airport for use by international commercial air transport
and/or international general aviation. (Refer to Airport/Facility Directory
and IFIM) (See [ICAO] International Airport)
[ICAO] International Airport -
Any airport designated by the Contracting State in whose territory
it is situated as an airport of entry and departure for international air
traffic, where the formalities incident to customs, immigration, public
health, animal and plant quarantine and similar procedures are carried
out.
[ICAO] International Civil Aviation Organization -
A specialized agency of the United Nations whose objective is
to develop the principles and techniques of international air navigation
and to foster planning and development of international civil air transport.
ICAO Regions include:
AFI African - Indian Ocean Region
CAR Caribbean Region (See chapter 8, section 8)
EUR European Region
MID/ASIA Middle East/Asia Region
NAM North American Region (See chapter 8, section 10)
NAT North Atlantic Region (See chapter 8, section 7)
PAC Pacific Region (See chapter 8, section 9)
SAM South American Region
International Flight Information Manual (IFIM) -
A publication designed primarily as a pilot's preflight planning
guide for flights into foreign airspace and for flights returning to the
U.S. from foreign locations.
Interrogator -
The ground based surveillance radar beacon transmitter/receiver,
which normally scans in synchronism with a primary radar, transmitting
discrete radio signals which repetitiously request all transponders on
the mode being used to reply. The replies received are mixed with the primary
radar returns and displayed on the same plan position indicator (radar
scope). Also, applied to the airborne element of the TACAN/DME system.
(See Transponder) (Refer to AIM)
Intersecting Runways -
Two or more runways which cross or meet within their lengths.
(See Intersection)
Intersection -
1. A point defined by any combination of courses, radials, or
bearings of two or more navigational aids.
2. Used to describe the point where two runways, a runway and
a taxiway, or two taxiways cross or meet.
Intersection Departure -
A departure from any runway intersection except the end of the
runway. (See Intersection)
Intersection Takeoff - (See Intersection Departure)
IR - (See IFR Military Training Routes)
I SAY AGAIN -
The message will be repeated.
J
Jamming -
Electronic or mechanical interference which may disrupt the display
of aircraft on radar or the transmission/reception of radio communications/navigation.
Jet Blast -
Jet engine exhaust (thrust stream turbulence). (See Wake Turbulence)
Jet Route -
A route designed to serve aircraft operations from 18,000 feet
MSL up to and including flight level 450. The routes are referred to as
"J" routes with numbering to identify the designated route; e.g., J105.
(See Class A airspace) (Refer to FAR Part 71)
Jet Stream -
A migrating stream of high speed winds present at high altitudes.
Jettisoning of External Stores -
Airborne release of external stores; e.g., tiptanks, ordnance.
(See Fuel Dumping) (Refer to FAR Part 91)
Joint Use Restricted Area - (See Restricted Area)
K
Known Traffic -
With respect to ATC clearances, means aircraft whose altitude,
position, and intentions are known to ATC.
L
LAA -
(See Local Airport Advisory)
LAAS - (See Low Altitude Alert System)
LAHSO -
An acronym for "Land and Hold Short Operation." These operations
include landing and holding short of an intersecting runway, a taxiway,
a predetermined point, or an approach/departure flightpath.
LAHSO - Dry -
Land and hold short operation on runways that are dry.
LAHSO - Wet -
Land and hold short operations on runways that are wet (but not
contaminated).
Land and Hold Short Operations -
Operations which include simultaneous takeoffs and landings and/or
simultaneous landings when a landing aircraft is able and is instructed
by the controller to hold-short of the intersecting runway/taxiway or designated
hold-short point. Pilots are expected to promptly inform the controller
if the hold short clearance cannot be accepted. (See Parallel Runways).
(Refer to AIM).
Landing Area -
Any locality either on land, water, or structures, including
airports/heliports and intermediate landing fields which is used, or intended
to be used, for the landing and takeoff of aircraft whether or not facilities
are provided for the shelter, servicing, or for receiving or discharging
passengers or cargo. (See [ICAO] Landing Area)
[ICAO] Landing Area -
That part of a movement area intended for the landing or takeoff
of aircraft.
Landing Direction Indicator -
A device which visually indicates the direction in which landings
and takeoffs should be made. (See Tetrahedron) (Refer to AIM)
[ICAO] Landing Distance Available (LDA) -
The length of runway which is declared available and suitable
for the ground run of an aeroplane landing.
Landing Minimums -
The minimum visibility prescribed for landing a civil aircraft
while using an instrument approach procedure. The minimum applies with
other limitations set forth in FAR Part 91 with respect to the Minimum
Descent Altitude (MDA) or Decision Height (DH) prescribed in the instrument
approach procedures as follows:
1. Straight-in landing minimums - A statement of MDA and visibility,
or DH and visibility, required for a straight-in landing on a specified
runway, or
2. Circling minimums - A statement of MDA and visibility required
for the circle-to-land maneuver.
Descent below the established MDA or DH is not authorized during
an approach unless the aircraft is in a position from which a normal approach
to the runway of intended landing can be made and adequate visual reference
to required visual cues is maintained. (See Straight-In Landing, Circle-to-Land
Maneuver, Decision Height, Minimum Descent Altitude, Visibility, Instrument
Approach Procedure) (Refer to FAR Part 91)
Landing Roll -
The distance from the point of touchdown to the point where the
aircraft can be brought to a stop or exit the runway.
Landing Sequence -
The order in which aircraft are positioned for landing (See Approach
Sequence)
Last Assigned Altitude -
The last altitude/flight level assigned by ATC and acknowledged
by the pilot. (See Maintain) (Refer to FAR Part 91)
Lateral Separation -
The lateral spacing of aircraft at the same altitude by requiring
operation on different routes or in different geographical locations. (See
Separation)
LDA - (See Localizer Type Directional Aid)
[ICAO] LDA - (See [ICAO] Landing Distance Available)
LF - (See Low Frequency)
Lighted Airport -
An airport where runway and obstruction lighting is available.
(See Airport Lighting) (Refer to AIM)
Light Gun -
A hand held directional light signaling device which emits a
brilliant narrow beam of white, green, or red light as selected by the
tower controller. The color and type of light transmitted can be used to
approve or disapprove anticipated pilot actions where radio communication
is not available. The light gun is used for controlling traffic operating
in the vicinity of the airport and on the airport movement area. (Refer
to AIM)
Localizer -
The component of an ILS which provides course guidance to the
runway. (See Instrument Landing System) (Refer to AIM) (See [ICAO] Localizer
Course)
[ICAO] Localizer Course (ILS) -
The locus of points, in any given horizontal plane, at which
the DDM (difference in depth of modulation) is zero.
Localizer Offset -
An angular offset of the localizer from the runway extended centerline
in a direction away from the no transgression zone (NTZ) that increases
the normal operating zone (NOZ) width. An offset requires a 50 foot increase
in DH and is not authorized for CAT II and CAT III approaches.
Localizer Type Directional Aid (LDA) -
A NAVAID used for nonprecision instrument approaches with utility
and accuracy comparable to a localizer but which is not a part of a complete
ILS and is not aligned with the runway. (Refer to AIM)
Localizer Usable Distance -
The maximum distance from the localizer transmitter at a specified
altitude, as verified by flight inspection, at which reliable course information
is continuously received. (Refer to AIM)
Local Airport Advisory (LAA) -
A service provided by flight service stations or the military
at airports not serviced by an operating control tower. This service consists
of providing information to arriving and departing aircraft concerning
wind direction and speed, favored runway, altimeter setting, pertinent
known traffic, pertinent known field conditions, airport taxi routes and
traffic patterns, and authorized instrument approach procedures. This information
is advisory in nature and does not constitute an ATC clearance (See Airport
Advisory Area)
Local Traffic -
Aircraft operating in the traffic pattern or within sight of
the tower, or aircraft known to be departing or arriving from flight in
local practice areas, or aircraft executing practice instrument approaches
at the airport. (See Traffic Pattern)
[ICAO] Locator -
An LM/MF NDB used as an aid to final approach.
Note: A locator usually has an average radius of rated
coverage of between 18.5 and 46.3 km (10 and 25 NM).
Longitudinal Separation -
The longitudinal spacing of aircraft at the same altitude by
a minimum distance expressed in units of time or miles. (See Separation)
(Refer to AIM)
Long Range Navigation - (See LORAN)
LORAN -
An electronic navigational system by which hyperbolic lines of
position are determined by measuring the difference in the time of reception
of synchronized pulse signals from two fixed transmitters. Loran A operates
in the 1750 to 1950 kHz frequency band. Loran C and D operate in the 100
to 110 kHz frequency band. (Refer to AIM)
Lost Communications -
Loss of the ability to communicate by radio. Aircraft are sometimes
referred to as NORDO (No Radio). Standard pilot procedures are specified
in FAR Part 91. Radar controllers issue procedures for pilots to follow
in the event of lost communications during a radar approach when weather
reports indicate that an aircraft will likely encounter IFR weather conditions
during the approach. (Refer to FAR Part 91, AIM)
Low Altitude Airway Structure -
The network of airways serving aircraft operations up to but
not including 18,000 feet MSL. (See Airway) (Refer to AIM)
LOW ALTITUDE ALERT, CHECK YOUR ALTITUDE IMMEDIATELY - (See Safety Alert)
Low Altitude Alert System (LAAS) -
An automated function of the TPX-42 that alerts the controller
when a Mode C transponder equipped aircraft on an IFR flight plan is below
a predetermined minimum safe altitude. If requested by the pilot, LAAS
monitoring is also available to VFR Mode C transponder equipped aircraft.
Low Approach -
An approach over an airport or runway following an instrument
approach or a VFR approach including the go around maneuver where the pilot
intentionally does not make contact with the runway. (Refer to AIM)
Low Frequency (LF) -
The frequency band between 30 and 300 kHz. (Refer to AIM)
M
MAA - (See Maximum Authorized Altitude)
Mach Number -
The ratio of true airspeed to the speed of sound; e.g., MACH
0.82, MACH 1.6. (See Airspeed)
[ICAO] Mach Technique -
Describes a control technique used by air traffic control whereby
turbojet aircraft operating successively along suitable routes are cleared
to maintain appropriate MACH numbers for a relevant portion of the enroute
phase of flight. The principle objective is to achieve improved utilization
of the airspace and to ensure that separation between successive aircraft
does not decrease below the established minima.
MAHWP -
Missed Approach Holding Waypoint
MAINTAIN -
a. Concerning altitude/flight level, the term means to remain
at the altitude/flight level specified. The phrase "climb and" or "descend
and" normally precedes "maintain" and the altitude assignment; e.g., "descend
and maintain 5,000."
b. Concerning other ATC instructions, the term is used in its
literal sense; e.g., maintain VFR.
Maintenance Planning Friction Level -
The friction level specified in AC 150/5320-12 which represents
the friction value below which the runway pavement surface remains acceptable
for any category or class of aircraft operations but which is beginning
to show signs of deterioration. This value will vary depending on the particular
friction measurement equipment used.
MAKE SHORT APPROACH -
Used by ATC to inform a pilot to alter his traffic pattern so
as to make a short final approach. (See Traffic Pattern)
Mandatory Altitude -
An altitude depicted on an instrument Approach Procedure Chart
requiring the aircraft to maintain altitude at the depicted value.
MAP - (See Missed Approach Point)
Marker Beacon -
An electronic navigation facility transmitting a 75 MHz vertical
fan or boneshaped radiation pattern. Marker beacons are identified by their
modulation frequency and keying code, and when received by compatible airborne
equipment, indicate to the pilot, both aurally and visually, that he is
passing over the facility. (See Outer Marker, Middle Marker, Inner Marker)
(Refer to AIM)
MARSA - (See Military Authority Assumes Responsibility For Separation Of Aircraft)
{New-98-3 Added February 26, 1998}
MAWP -
Missed Approach Waypoint
Maximum Authorized Altitude (MAA) -
A published altitude representing the maximum usable altitude
or flight level for an airspace structure or route segment. It is the highest
altitude on a Federal airway, jet route, area navigation low or high route,
or other direct route for which an MEA is designated in FAR Part 95 at
which adequate reception of navigation aid signals is assured.
MAWP -
Missed Approach Waypoint
MAYDAY -
The international radio telephony distress signal. When repeated
three times, it indicates imminent and grave danger and that immediate
assistance is requested. (See Pan-Pan) (Refer to AIM)
MCA - (See Minimum Crossing Altitude)
MDA - (See Minimum Descent Altitude)
MEA - (See Minimum Enroute IFR Altitude)
Meteorological Impact Statement (MIS) -
An unscheduled planning forecast describing conditions expected
to begin within 4 to 12 hours which may impact the flow of air traffic
in a specific center's (ARTCC) area.
Meter Fix Time (MFT)/Slot Time -
A calculated time to depart the meter fix in order to cross the
vertex at the ACLT. This time reflects descent speed adjustment and any
applicable time that must be absorbed prior to crossing the meter fix.
{New-98-8 Revised August 13, 1998. Added "/MDM"}
Meter List Display Interval (MLDI) -
A dynamic parameter which controls the number of minutes prior
to the flight plan calculated time of arrival at the meter fix for each
aircraft, at which time the TCLT is frozen and becomes an ACLT; i.e., the
VTA is updated and consequently the TCLT modified as appropriate until
frozen at which time updating is suspended and an ACLT is assigned. When
frozen, the flight entry is inserted into the arrival sector's meter list
for display on the sector PVD/MDM. MLDI is used if filed true airspeed
is less than or equal to freeze speed parameters (FSPD).
Metering -
A method of time regulating arrival traffic flow into a terminal
area so as not to exceed a predetermined terminal acceptance rate.
Metering Airports -
Airports adapted for metering and for which optimum flight paths
are defined. A maximum of 15 airports may be adapted.
Metering Fix -
A fix along an established route from over which aircraft will
be metered prior to entering terminal airspace. Normally, this fix should
be established at a distance from the airport which will facilitate a profile
descent 10,000 feet above airport elevation (AAE) or above.
{New-98-8 Revised August 13, 1998. Added "/MDM's"}
Metering Position(s) -
Adapted PVD's/MDM's and associated "D" positions eligible for
display of a metering position list. A maximum of four PVD's/MDM's may
be adapted.
{New-98-8 Revised August 13, 1998. Added "/MDM's"}
Metering Position List -
An ordered list of data on arrivals for a selected metering airport
displayed on a metering position PVD/MDM.
MFT - (See Meter Fix Time/Slot Time)
MHA - (See Minimum Holding Altitude)
MIA - (See Minimum IFR Altitudes)
Microburst -
A small downburst with outbursts of damaging winds extending
2.5 miles or less. In spite of its small horizontal scale, an intense microburst
could induce wind speeds as high as 150 knots. (Refer to AIM)
Microwave Landing System (MLS) -
A precision instrument approach system operating in the microwave
spectrum which normally consists of the following components:
1. Azimuth Station.
2. Elevation Station.
3. Precision Distance Measuring Equipment. (See MLS Categories)
Middle Compass Locator - (See Compass Locator)
Middle Marker (MM) -
A marker beacon that defines a point along the glideslope of
an ILS normally located at or near the point of decision height (ILS Category
I). It is keyed to transmit alternate dots and dashes, with the alternate
dots and dashes keyed at the rate of 95 dot/dash combinations per minute
on a 1300 Hz tone, which is received aurally and visually by compatible
airborne equipment. (See Marker Beacon, Instrument Landing System) (Refer
to AIM)
Mid RVR - (See Visibility)
Miles In Trail -
A specified distance between aircraft, normally, in the same
stratum associated with the same destination or route of flight.
Military Authority Assumes Responsibility For Separation Of Aircraft
(MARSA) -
A condition whereby the military services involved assume responsibility
for separation between participating military aircraft in the ATC system.
It is used only for required IFR operations which are specified in letters
of agreement or other appropriate FAA or military documents.
Military Operations Area (MOA) - (See Special Use Airspace)
Military Training Routes (MTR) -
Airspace of defined vertical and lateral dimensions established
for the conduct of military flight training at airspeeds in excess of 250
knots IAS. (See IFR Military Training Routes and VFR Military Training
Routes)
Minima - (See Minimums)
Minimum Crossing Altitude (MCA) -
The lowest altitude at certain fixes at which an aircraft must
cross when proceeding in the direction of a higher minimum enroute IFR
altitude (MEA). (See Minimum Enroute IFR Altitude)
Minimum Descent Altitude (MDA) -
The lowest altitude, expressed in feet above mean sea level,
to which descent is authorized on final approach or during circle-to-land
maneuvering in execution of a standard instrument approach procedure where
no electronic glideslope is provided. (See Nonprecision Approach Procedure)
Minimum Enroute IFR Altitude (MEA) -
The lowest published altitude between radio fixes which assures
acceptable navigational signal coverage and meets obstacle clearance requirements
between those fixes. The MEA prescribed for a Federal airway or segment
thereof, area navigation low or high route or other direct route applies
to the entire width of the airway, segment, or route between the radio
fixes defining the airway, segment, or route. (Refer to FAR Parts 91 and
95; AIM)
Minimum Friction Level -
The friction level specified in AC 150/5320-12 that represents
the minimum recommended wet pavement surface friction value for any turbojet
aircraft engaged in LAHSO. This value will vary with the particular friction
measurement equipment used.
Minimum Fuel -
Indicates that an aircraft's fuel supply has reached a state
where, upon reaching the destination, it can accept little or no delay.
This is not an emergency situation but merely indicates an emergency situation
is possible should any undue delay occur. (Refer to AIM)
Minimum Holding Altitude (MHA) -
The lowest altitude prescribed for a holding pattern which assures
navigational signal coverage, communications, and meets obstacle clearance
requirements.
Minimum IFR Altitudes (MIA) -
Minimum altitudes for IFR operations as prescribed in FAR Part
91. These altitudes are published on aeronautical charts and prescribed
in FAR Part 95 for airways and routes, and in FAR Part 97 for standard
instrument approach procedures. If no applicable minimum altitude is prescribed
in FAR Part 95 or FAR Part 97, the following minimum IFR altitude applies:
1. In designated mountainous areas, 2,000 feet above the highest
obstacle within a horizontal distance of 4 nautical miles from the course
to be flown; or
2. Other than mountainous areas, 1,000 feet above the highest
obstacle within a horizontal distance of 4 nautical miles from the course
to be flown; or
3. As otherwise authorized by the Administrator or assigned
by ATC.
(See Minimum Enroute IFR Altitude, Minimum Obstruction Clearance
Altitude, Minimum Crossing Altitude, Minimum Safe Altitude, Minimum Vectoring
Altitude) (Refer to FAR Part 91)
Minimum Navigation Performance Specification (MNPS) -
A set of standards which require aircraft to have a minimum navigation
performance capability in order to operate in MNPS designated airspace.
In addition, aircraft must be certified by their State of Registry for
MNPS operation.
Minimum Navigation Performance Specifications Airspace (MNPSA) -
Designated airspace in which MNPS procedures are applied between
MNPS certified and equipped aircraft. Under certain conditions, non-MNPS
aircraft can operate in MNPSA. However, standard oceanic separation minima
is provided between the non-MNPS aircraft and other traffic. Currently,
the only designated MNPSA is described as follows:
{New-98-3 Revised February 26, 1998}
a. Between FL 285 and FL 420:
b. Between latitudes 27° N and the North Pole;
c. In the east, the eastern boundaries of the CTA's Santa Maria
Oceanic, Shanwick Oceanic, and Reykjavik;
d. In the west, the western boundaries of CTA's Reykjavik and
Gander Oceanic and New York Oceanic excluding the area west of 60°
W and south of 38°30' N.
Minimum Obstruction Clearance Altitude (MOCA) -
The lowest published altitude in effect between radio fixes on
VOR airways, off airway routes, or route segments which meets obstacle
clearance requirements for the entire route segment and which assures acceptable
navigational signal coverage only within 25 statute (22 nautical) miles
of a VOR. (Refer to FAR Part 91 and FAR Part 95)
Minimum Reception Altitude (MRA) -
The lowest altitude at which an intersection can be determined.
(Refer to FAR Part 95)
Minimum Safe Altitude (MSA) -
1. The minimum altitude specified in FAR Part 91 for various
aircraft operations.
2. Altitudes depicted on approach charts which provide at least
1,000 feet of obstacle clearance for emergency use within a specified distance
from the navigation facility upon which a procedure is predicated. These
altitudes will be identified as Minimum Sector Altitudes or Emergency Safe
Altitudes and are established as follows:
a. Minimum Sector Altitudes - Altitudes depicted on approach
charts which provide at least 1,000 feet of obstacle clearance within a
25 mile radius of the navigation facility upon which the procedure is predicated.
Sectors depicted on approach charts must be at least 90 degrees in scope.
These altitudes are for emergency use only and do not necessarily assure
acceptable navigational signal coverage. (See [ICAO] Minimum Sector Altitude)
b. Emergency Safe Altitudes - Altitudes depicted on approach
charts which provide at least 1,000 feet of obstacle clearance in nonmountainous
areas and 2,000 feet of obstacle clearance in designated mountainous areas
within a 100 mile radius of the navigation facility upon which the procedure
is predicated and normally used only in military procedures. These altitudes
are identified on published procedures as "Emergency Safe Altitudes."
Minimum Safe Altitude Warning (MSAW) -
A function of the ARTS III computer that aids the controller
by alerting him when a tracked Mode C equipped aircraft is below or is
predicted by the computer to go below a predetermined minimum safe altitude.
(Refer to AIM)
[ICAO] Minimum Sector Altitude -
The lowest altitude which may be used under emergency conditions
which will provide a minimum clearance of 300 m (1,000 feet) above all
obstacles located in an area contained within a sector of a circle of 46
km (25 NM) radius centered on a radio aid to navigation.
Minimums -
Weather condition requirements established for a particular operation
or type of operation; e.g., IFR takeoff or landing, alternate airport for
IFR flight plans, VFR flight, etc. (See Landing Minimums, IFR Takeoff Minimums,
VFR Conditions, IFR Conditions) (Refer to FAR Part 91, AIM)
Minimum Vectoring Altitude (MVA) -
The lowest MSL altitude at which an IFR aircraft will be vectored
by a radar controller, except as otherwise authorized for radar approaches,
departures, and missed approaches. The altitude meets IFR obstacle clearance
criteria. It may be lower than the published MEA along an airway or J-route
segment. It may be utilized for radar vectoring only upon the controller's
determination that an adequate radar return is being received from the
aircraft being controlled. Charts depicting minimum vectoring altitudes
are normally available only to the controllers and not to pilots. (Refer
to AIM)
Minutes In Trail -
A specified interval between aircraft expressed in time. This
method would more likely be utilized regardless of altitude.
MIS - (See Meteorological Impact Statement)
MISSED APPROACH -
1. A maneuver conducted by a pilot when an instrument approach
cannot be completed to a landing. The route of flight and altitude are
shown on instrument approach procedure charts. A pilot executing a missed
approach prior to the Missed Approach Point (MAP) must continue along the
final approach to the MAP. The pilot may climb immediately to the altitude
specified in the missed approach procedure.
2. A term used by the pilot to inform ATC that he is executing
the missed approach.
3. At locations where ATC radar service is provided, the pilot
should conform to radar vectors when provided by ATC in lieu of the published
missed approach procedure. (See Missed Approach Point) (Refer to AIM)
Missed Approach Point (MAP) -
A point prescribed in each instrument approach procedure at which
a missed approach procedure shall be executed if the required visual reference
does not exist. (See Missed Approach, Segments of an Instrument Approach
Procedure)
[ICAO] Missed Approach Procedure -
The procedure to be followed if the approach cannot be continued.
Missed Approach Segment - (See Segments of an Instrument Approach Procedure)
MLDI - (See Meter List Display Interval)
MLS - (See Microwave Landing System)
MLS Categories -
1. MLS Category I - An MLS approach procedure which provides
for an approach to a height above touchdown of not less than 200 feet and
a runway visual range of not less than 1,800 feet.
2. MLS Category II - Undefined until data gathering/analysis
completion.
3. MLS Category III - Undefined until data gathering/analysis
completion.
MM - (See Middle Marker)
MNPS - (See Minimum Navigation Performance Specification)
MNPSA - (See Minimum Navigation Performance Specifications Airspace)
MOA - (See Military Operations Area)
MOCA - (See Minimum Obstruction Clearance Altitude)
MODE -
The letter or number assigned to a specific pulse spacing of
radio signals transmitted or received by ground interrogator or airborne
transponder components of the Air Traffic Control Radar Beacon System (ATCRBS).
Mode A (military Mode 3) and Mode C (altitude reporting) are used in air
traffic control. (See Transponder, Interrogator, Radar) (Refer to AIM)
(See [ICAO] Mode)
[ICAO] Mode (SSR Mode) -
The letter or number assigned to a specific pulse spacing of
the interrogation signals transmitted by an interrogator. There are 4 modes,
A, B, C and D specified in Annex 10, corresponding to four different interrogation
pulse spacings.
Mode C Intruder Alert -
A function of certain air traffic control automated systems designed
to alert radar controllers to existing or pending situations between a
tracked target (known IFR or VFR aircraft) and an untracked target (unknown
IFR or VFR aircraft) that requires immediate attention/action. (See Conflict
Alert)
MONITOR -
(When used with communication transfer) listen on a specific
frequency and stand by for instructions. Under normal circumstances do
not establish communications.
{New-98-3 Added February 26, 1998}
Monitor Alert (MA) -
A function of the ETMS that provides traffic management
personnel with a tool for predicting potential capacity problems in individual
operational sectors. The MA is an indication that traffic management personnel
need to analyze a particular sector for actual activity and to determine
the required action(s), if any, needed to control the demand.
{New-98-3 Added February 26, 1998}
Monitor Alert Parameter (MAP) -
The number designated for use in monitor alert processing
by the ETMS. The MAP is designated for each operational sector for increments
of 15 minutes.
Movement Area -
The runways, taxiways, and other areas an of airport/heliport
which are utilized for taxiing/hover taxiing, air taxiing, takeoff, and
landing of aircraft, exclusive of loading ramps and parking areas. At those
airport/heliports with a tower, specific approval for entry onto the movement
area must be obtained from ATC. (See [ICAO] Movement Area)
[ICAO] Movement Area -
That part of an aerodrome to be used for the takeoff, landing
and taxiing of aircraft, consisting of the maneuvering area and the apron(s).
Moving Target Indicator (MTI) -
An electronic device which will permit radar scope presentation
only from targets which are in motion. A partial remedy for ground clutter.
MRA - (See Minimum Reception Altitude)
MSA - (See Minimum Safe Altitude)
MSAW - (See Minimum Safe Altitude Warning)
MTI - (See Moving Target Indicator)
MTR - (See Military Training Routes)
Multicom -
A mobile service not open to public correspondence used to provide
communications essential to conduct the activities being performed by or
directed from private aircraft.
Multiple Runways -
The utilization of a dedicated arrival runway(s) for departures
and a dedicated departure runway(s) for arrivals when feasible to reduce
delays and enhance capacity.
MVA - (See Minimum Vectoring Altitude)
N
NAS - (See National Airspace System)
NAS Stage A -
The enroute ATC system's radar, computers and computer programs,
controller plan view displays (PVDs/Radar Scopes), input/output devices,
and the related communications equipment which are integrated to form the
heart of the automated IFR air traffic control system. This equipment performs
Flight Data Processing (FDP) and Radar Data Processing (RDP). It interfaces
with automated terminal systems and is used in the control of enroute IFR
aircraft. (Refer to AIM)
National Airspace System (NAS) -
The common network of U.S. airspace; air navigation facilities,
equipment and services, airports or landing areas; aeronautical charts,
information and services; rules, regulations and procedures, technical
information, and manpower and material. Included are system components
shared jointly with the military.
National Beacon Code Allocation Plan Airspace -
Airspace over United States territory located within the North
American continent between Canada and Mexico, including adjacent territorial
waters outward to about boundaries of oceanic control areas (CTA)/Flight
Information Regions (FIR). (See Flight Information Region)
National Flight Data Center (NFDC) -
A facility in Washington D.C., established by FAA to operate
a central aeronautical information service for the collection, validation,
and dissemination of aeronautical data in support of the activities of
government, industry, and the aviation community. The information is published
in the National Flight Data Digest. (See National Flight Data Digest)
National Flight Data Digest (NFDD) -
A daily (except weekends and Federal holidays) publication of
flight information appropriate to aeronautical charts, aeronautical publications,
Notices to Airmen, or other media serving the purpose of providing operational
flight data essential to safe and efficient aircraft operations.
{New-98-3 Added February 26, 1998}
National Route Program (NRP) -
The NRP is a set of rules and procedures which are designed
to increase the flexibility of user flight planning within published guidelines.
National Search And Rescue Plan -
An interagency agreement which provides for the effective utilization
of all available facilities in all types of search and rescue missions.
Navaid - (See Navigational Aid)
Navaid Classes -
VOR, VORTAC, AND TACAN aids are classed according to their operational
use. The three classes of NAVAIDs are:
T - Terminal.
L - Low altitude.
H - High altitude.
The normal service range for T, L, and H class aids is found
in the FAAAIMTOC. Certain operational requirements make it necessary to
use some of these aids at greater service ranges than specified. Extended
range is made possible through flight inspection determinations. Some aids
also have lesser service range due to location, terrain, frequency protection,
etc. Restrictions to service range are listed in Airport/Facility Directory.
Navigable Airspace -
Airspace at and above the minimum flight altitudes prescribed
in the FARs including airspace needed for safe takeoff and landing. (Refer
to FAR Part 91)
Navigational Aid (NAVAID) -
Any visual or electronic device airborne or on the surface which
provides point-to-point guidance information or position data to aircraft
in flight. (See Air Navigation Facility)
NBCAP Airspace - (See National Beacon Code Allocation Plan Airspace)
NDB - (See Nondirectional Beacon)
NEGATIVE -
"No," or "permission not granted," or "that is not correct."
NEGATIVE CONTACT -
Used by pilots to inform ATC that:
1. Previously issued traffic is not in sight. It may be followed
by the pilot's request for the controller to provide assistance in avoiding
the traffic.
2. They were unable to contact ATC on a particular frequency.
NFDC - (See National Flight Data Center)
NFDD - (See National Flight Data Digest)
Night -
The time between the end of evening civil twilight and the beginning
of morning civil twilight, as published in the American Air Almanac, converted
to local time. (See [ICAO] Night)
[ICAO] Night -
The hours between the end of evening civil twilight and the beginning
of morning civil twilight or such other period between sunset and sunrise
as may be specified by the appropriate authority.
Note: Civil twilight ends in the evening when the center
of the sun's disk is 6 degrees below the horizon and begins in the morning
when the center of the sun's disk is 6 degrees below the horizon.
NO GYRO APPROACH -
A radar approach/vector provided in case of a malfunctioning
gyro compass or directional gyro. Instead of providing the pilot with headings
to be flown, the controller observes the radar track and issues control
instructions "turn right/left" or "stop turn" as appropriate. (Refer to
AIM)
NO GYRO VECTOR - (See No Gyro Approach)
NO TRANSGRESSION ZONE (NTZ) -
The NTZ is a 2,000 foot wide zone, located equidistant between
parallel runway final approach courses in which flight is not allowed.
Nonapproach Control Tower -
Authorizes aircraft to land or takeoff at the airport controlled
by the tower or to transit the Class D airspace. The primary function of
a nonapproach control tower is the sequencing of aircraft in the traffic
pattern and on the landing area. Nonapproach control towers also separate
aircraft operating under instrument flight rules clearances from approach
controls and centers. They provide ground control services to aircraft,
vehicles, personnel and equipment on the airport movement area.
Noncommon Route/Portion -
That segment of a North American Route between the inland navigation
facility and a designated North American terminal.
Noncomposite Separation -
Separation in accordance with minima other than the composite
separation minimum specified for the area concerned.
Nondirectional Beacon (NDB) -
An L/MF or UHF radio beacon transmitting nondirectional signals
whereby the pilot of an aircraft equipped with direction finding equipment
can determine his bearing to or from the radio beacon and "home" on or
track to or from the station. When the radio beacon is installed in conjunction
with the Instrument Landing System marker, it is normally called a Compass
Locator. (See Compass Locator, Automatic Direction Finder)
Nonmovement Areas -
Taxiways and apron (ramp) areas not under the control of air
traffic.
Nonprecision Approach - (See Nonprecision Approach Procedure)
Nonprecision Approach Procedure -
A standard instrument approach procedure in which no electronic
glideslope is provided; e.g., VOR, TACAN, NDB, LOC, ASR, LDA, or SDF approaches.
Nonradar -
Precedes other terms and generally means without the use of radar,
such as:
1. Nonradar Approach - Used to describe instrument approaches
for which course guidance on final approach is not provided by ground based
precision or surveillance radar. Radar vectors to the final approach course
may or may not be provided by ATC. Examples of nonradar approaches are
VOR, NDB, TACAN, and ILS/MLS approaches. (See Final Approach - IFR, Final
Approach Course, Radar Approach, Instrument Approach Procedure)
2. Nonradar Approach Control - An ATC facility providing approach
control service without the use of radar. (See Approach Control Facility,
Approach Control Service)
3. Nonradar Arrival - An aircraft arriving at an airport without
radar service or at an airport served by a radar facility and radar contact
has not been established or has been terminated due to a lack of radar
service to the airport. (See Radar Arrival, Radar Service)
4. Nonradar Route - A flight path or route over which the pilot
is performing his own navigation. The pilot may be receiving radar separation,
radar monitoring, or other ATC services while on a nonradar route. (See
Radar Route)
5. Nonradar Separation - The spacing of aircraft in accordance
with established minima without the use of radar; e.g., vertical, lateral,
or longitudinal separation. (See Radar Separation) (See [ICAO] Nonradar
Separation)
[ICAO] Nonradar Separation -
The separation used when aircraft position information is derived
from sources other than radar.
NOPAC - (See North Pacific)
NORDO - (See Lost Communications)
Normal Operating Zone (NOZ) -
The NOZ is the operating zone within which aircraft flight remains
during normal independent simultaneous parallel ILS approaches.
North American Route -
A numerically coded route preplanned over existing airway and
route systems to and from specific coastal fixes serving the North Atlantic.
North American Routes consist of the following:
1. Common Route/Portion - That segment of a North American Route
between the inland navigation facility and the coastal fix.
2. Noncommon Route/Portion - That segment of a North American
Route between the inland navigation facility and a designated North American
terminal.
3. Inland Navigation Facility - A navigation aid on a North
American Route at which the common route and/or the noncommon route begins
or ends.
4. Coastal Fix - A navigation aid or intersection where an aircraft
transitions between the domestic route structure and oceanic route structure.
North Mark -
A beacon data block sent by the host computer to be displayed
by the ARTS on a 360 degree bearing at a locally selected radar azimuth
and distance. The North Mark is used to ensure correct range/azimuth orientation
during periods of CENRAP.
North Pacific (NOPAC) -
An organized route system between the Alaskan west coast and
Japan.
NOTAM - (See Notice To Airmen)
Notice To Airmen (NOTAM) -
A notice containing information (not known sufficiently in advance
to publicize by other means) concerning the establishment, condition, or
change in any component (facility, service, or procedure of, or hazard
in the National Airspace System) the timely knowledge of which is essential
to personnel concerned with flight operations.
1. NOTAM(D) - A NOTAM given (in addition to local dissemination)
distant dissemination beyond the area of responsibility of the Flight Service
Station. These NOTAMs will be stored and available until canceled.
2. NOTAM(L) - A NOTAM given local dissemination by voice and
other means, such as telautograph and telephone, to satisfy local user
requirements.
3. FDC NOTAM - A NOTAM regulatory in nature, transmitted by
USNOF and given system wide dissemination.
(See [ICAO] NOTAM)
[ICAO] NOTAM -
A notice containing information concerning the establishment,
condition or change in any aeronautical facility, service procedure or
hazard, the timely knowledge of which is essential to personnel concerned
with flight operations.
Class I Distribution. Distribution by means of telecommunication.
Class II Distribution. Distribution by means other than telecommunications.
Notices To Airmen Publication -
{New-98-3 Revised February 26, 1998}
A publication issued every 28 days, designed primarily for the
pilot, which contains current NOTAM information considered essential to
the safety of flight as well as supplemental data to other aeronautical
publications. The contraction NTAP is used in NOTAM text. (See Notice to
Airmen)
NTAP -
(See Notices to Airmen Publication)
NUMEROUS TARGETS VICINITY (LOCATION) -
A traffic advisory issued by ATC to advise pilots that targets
on the radar scope are too numerous to issue individually. (See Traffic
Advisories)
O
OALT - (See Operational Acceptable Level of Traffic)
Obstacle -
An existing object, object of natural growth, or terrain at a
fixed geographical location or which may be expected at a fixed location
within a prescribed area with reference to which vertical clearance is
or must be provided during flight operation.
Obstacle Free Zone (OFZ) -
The OFZ is a three dimensional volume of airspace which protects
for the transition of aircraft to and from the runway. The OFZ clearing
standard precludes taxiing and parked airplanes and object penetrations,
except for frangible NAVAID locations that are fixed by function. Additionally,
vehicles, equipment, and personnel may be authorized by air traffic control
to enter the area using the provisions of FAA Order 7110.65, paragraph
3-1-5, Vehicles/Equipment/Personnel on Runways. The runway OFZ and when
applicable, the inner-approach OFZ, and the inner-transitional OFZ, comprise
the OFZ.
a. Runway OFZ. The runway OFZ is a defined volume of airspace
centered above the runway. The runway OFZ is the airspace above a surface
whose elevation at any point is the same as the elevation of the nearest
point on the runway centerline. The runway OFZ extends 200 feet beyond
each end of the runway. The width is as follows:
1. For runways serving large airplanes, the greater of:
(a) 400 feet, or
(b) 180 feet, plus the wingspan of the most demanding
airplane, plus 20 feet per 1,000 feet of airport elevation.
2. For runways serving only small airplanes:
(a) 300 feet for precision instrument runways.
(b) 250 feet for other runways serving small airplanes
with approach speeds of 50 knots, or more.
(c) 120 feet for other runways serving small airplanes
with approach speeds of less than 50 knots.
b. Inner-approach OFZ. The inner-approach OFZ is a defined volume
of airspace centered on the approach area. The inner-approach OFZ applies
only to runways with an approach lighting system. The inner-approach OFZ
begins 200 feet from the runway threshold at the same elevation as the
runway threshold and extends 200 feet beyond the last light unit in the
approach lighting system. The width of the inner-approach OFZ is the same
as the runway OFZ and rises at a slope of 50 (horizontal) to 1 (vertical)
from the beginning.
c. Inner-transitional OFZ. The inner transitional surface OFZ
is a defined volume of airspace along the sides of the runway and inner-approach
OFZ and applies only to precision instrument runways. The inner-transitional
surface OFZ slopes 3 (horizontal) to 1 (vertical) out from the edges of
the runway OFZ and inner-approach OFZ to a height of 150 feet above the
established airport elevation.
(Refer to AC 150/5300-13, Chapter 3 and FAA Order 7110.65, paragraph
3-1-5, Vehicles/Equipment/Personnel on Runways.)
Obstruction -
Any object/obstacle exceeding the obstruction standards specified
by FAR Part 77, Subpart C.
Obstruction Light -
A light or one of a group of lights, usually red or white, frequently
mounted on a surface structure or natural terrain to warn pilots of the
presence of an obstruction.
Oceanic Airspace -
Airspace over the oceans of the world, considered international
airspace, where oceanic separation and procedures per the International
Civil Aviation Organization are applied. Responsibility for the provisions
of air traffic control service in this airspace is delegated to various
countries, based generally upon geographic proximity and the availability
of the required resources.
Oceanic Display and Planning System (ODAPS) -
An automated digital display system which provides flight data
processing, conflict probe, and situation display for oceanic air traffic
control.
Oceanic Navigational Error Report (ONER) -
A report filed when an aircraft exiting oceanic airspace has
been observed by radar to be off course. ONER reporting parameters and
procedures are contained on Order 7110.82, Monitoring of Navigational Performance
In Oceanic Areas.
Oceanic Published Route -
A route established in international airspace and charted or
described in flight information publications, such as route Charts, DOD
Enroute Charts, Chart Supplements, NOTAMs and Track Messages.
Oceanic Transition Route (OTR) -
An ATS route established for the purpose of transitioning aircraft
to/from an organized track system.
ODAPS - (See Oceanic Display and Planning System)
Off Course -
A term used to describe a situation where an aircraft has reported
a position fix or is observed on radar at a point not on the ATC approved
route of flight.
Official Weather -
Official Weather is the last weather sequence that has been transmitted
long line. Long Line dissemination is the transmission of weather data
via a communications network on a regional or national scale. When the
Automated Surface Observing System (ASOS) Operator Interface Device (OID)
is in the "edit mode" the displayed weather is not the official weather
until it has been transmitted long line.
Offshore Control Area -
That portion of airspace between the U.S. 12 mile limit and the
oceanic CTA/FIR boundary within which air traffic control is exercised.
These areas are established to permit the application of domestic procedures
in the provision of air traffic control services. Offshore control area
is generally synonymous with Federal Aviation Regulations, Part 71, Subpart
E, "Control Areas and Control Area Extensions."
Off Route Vector -
A vector by ATC which takes an aircraft off a previously assigned
route. Altitudes assigned by ATC during such vectors provide required obstacle
clearance.
Offset Parallel Runways -
Staggered runways having centerlines which are parallel.
OFT - (See Outer Fix Time)
OFZ - (See Obstacle Free Zone)
OM - (See Outer Marker)
Omega -
An RNAV system designed for long range navigation based upon
ground based electronic navigational aid signals.
{New-98-3 Added February 26, 1998}
One-Minute Weather -
The most recent one minute update weather broadcast received
by a pilot from an uncontrolled airport ASOS/AWOS.
ONER - (See Oceanic Navigational Error Report)
Operational - (See Due Regard)
ON COURSE -
1. Used to indicate that an aircraft is established on the route
centerline.
2. Used by ATC to advise a pilot making a radar approach that
his aircraft is lined up on the final approach course. (See On Course Indication)
On Course Indication -
An indication on an instrument, which provides the pilot a visual
means of determining that the aircraft is located on the centerline of
a given navigational track, or an indication on a radar scope that an aircraft
is on a given track.
Operational Acceptable Level of Traffic (OALT) -
An air traffic activity level associated with the designed capacity
for a sector or airport. The OALT considers dynamic changes in staffing,
personnel experience levels, equipment outages, operational configurations,
weather, traffic complexity, aircraft performance mixtures, transitioning
flights, adjacent airspace, handoff/point-out responsibilities, and other
factors that may affect an air traffic operational position or system element.
The OALT is normally considered to be the total number of aircraft that
any air traffic functional position can accommodate for a defined period
of time under a given set of circumstances.
Opposite Direction Aircraft -
Aircraft are operating in opposite directions when:
1. They are following the same track in reciprocal directions;
or
2. Their tracks are parallel and the aircraft are flying in
reciprocal directions; or
3. Their tracks intersect at an angle of more than 135 degrees.
Option Approach -
An approach requested and conducted by a pilot which will result
in either a touch and go, missed approach, low approach, stop and go, or
full stop landing. (See Cleared for the Option) (Refer to AIM)
Organized Track System -
A moveable system of oceanic tracks that traverses the North
Atlantic between Europe and North America the physical position of which
is determined twice daily taking the best advantage of the winds aloft.
Organized Track System -
A series of ATS routes which are fixed and charted; i.e., CEP,
NOPAC, or flexible and described by NOTAM; i.e., NAT TRACK MESSAGE.
OROCA -
An off-route altitude which provides obstruction clearance with
a 1,000 foot buffer in nonmountainous terrain areas and a 2,000 foot buffer
in designated mountainous areas within the United States. This altitude
may not provide signal coverage from ground-based navigational aids, air
traffic control radar, or communications coverage.
OTR - (See Oceanic Transition Route)
OTS - (See Organized Track System)
OUT -
The conversation is ended and no response is expected.
Outer Area (associated with Class C airspace) -
Nonregulatory airspace surrounding designated Class C airspace
airports wherein ATC provides radar vectoring and sequencing on a full-time
basis for all IFR and participating VFR aircraft. The service provided
in the outer area is called Class C service which includes: IFR/IFR - standard
IFR separation; IFR/VFR - traffic advisories and conflict resolution; and
VFR/VFR - traffic advisories and, as appropriate, safety alerts. The normal
radius will be 20 nautical miles with some variations based on site specific
requirements. The outer area extends outward from the primary Class C airspace
airport and extends from the lower limits of radar/radio coverage up to
the ceiling of the approach control's delegated airspace excluding the
Class C charted area and other airspace as appropriate. (See Controlled
Airspace, Conflict Resolution)
Outer Compass Locator - (See Compass Locator)
Outer Fix -
A general term used within ATC to describe fixes in the terminal
area, other than the final approach fix. Aircraft are normally cleared
to these fixes by an Air Route Traffic Control Center or an Approach Control
Facility. Aircraft are normally cleared from these fixes to the final approach
fix or final approach course.
Outer Fix -
An adapted fix along the converted route of flight, prior to
the meter fix, for which crossing times are calculated and displayed in
the metering position list.
Outer Fix Time (OFT) -
A calculated time to depart the outer fix in order to cross the
vertex at the ACLT. The time reflects descent speed adjustments and any
applicable delay time that must be absorbed prior to crossing the meter
fix.
Outer Marker (OM) -
A marker beacon at or near the glideslope intercept altitude
of an ILS approach. It is keyed to transmit two dashes per second on a
400 Hz tone, which is received aurally and visually by compatible airborne
equipment. The OM is normally located four to seven miles from the runway
threshold on the extended centerline of the runway. (See Marker Beacon,
Instrument Landing System) (Refer to AIM)
OVER -
My transmission is ended; I expect a response.
Overhead Maneuver -
A series of predetermined maneuvers prescribed for aircraft (often
in formation) for entry into the visual flight rules (VFR) traffic pattern
and to proceed to a landing. An overhead maneuver is not an instrument
flight rules (IFR) approach procedure. An aircraft executing an overhead
maneuver is considered VFR and the IFR flight plan is canceled when the
aircraft reaches the "initial point" on the initial approach portion of
the maneuver. The pattern usually specifies the following:
a. The radio contact required of the pilot.
b. The speed to be maintained.
c. An initial approach 3 to 5 miles in length.
d. An elliptical pattern consisting of two 180 degree turns.
e. A break point at which the first 180 degree turn is started.
f. The direction of turns.
g. Altitude (at least 500 feet above the conventional pattern).
h. A "Roll-out" on final approach not less than 1/4 mile from
the landing threshold and not less than 300 feet above the ground.
Overlying Center -
The ARTCC facility that is responsible for arrival/departure
operations at a specific terminal.
P
P Time - (See Proposed Departure Time)
PAN-PAN -
The international radio telephony urgency signal. When repeated
three times, indicates uncertainty or alert followed by the nature of the
urgency. (See MAYDAY) (Refer to AIM)
PAR - (See Precision Approach Radar)
[ICAO] PAR - (See [ICAO] Precision Approach Radar)
Parallel ILS Approaches -
Approaches to parallel runways by IFR aircraft which, when established
inbound toward the airport on the adjacent final approach courses, are
radar separated by at least 2 miles. (See Final Approach Course, Simultaneous
ILS Approaches).
Parallel MLS Approaches - (See Parallel ILS Approaches)
Parallel Offset Route -
A parallel track to the left or right of the designated or established
airway/route. Normally associated with Area Navigation (RNAV) operations.
(See Area Navigation)
Parallel Runways -
Two or more runways at the same airport whose centerlines are
parallel. In addition to runway number, parallel runways are designated
as L (left) and R (right) or, if three parallel runways exist, L (left),
C (center), or R (right).
PATWAS - (See Pilots Automatic Telephone Weather Answering Service)
PBCT - (See Proposed Boundary Crossing Time)
Permanent Echo -
Radar signals reflected from fixed objects on the earth's surface;
e.g., buildings, towers, terrain. Permanent echoes are distinguished from
"ground clutter" by being definable locations rather than large areas.
Under certain conditions they may be used to check radar alignment.
Photo Reconnaissance (PR) -
Military activity that requires locating individual photo targets
and navigating to the targets at a preplanned angle and altitude. The activity
normally requires a lateral route width of 16 NM and altitude range of
1,500 feet to 10,000 feet AGL.
PIDP - (See Programmable Indicator Data Processor)
Pilot Briefing -
A service provided by the FSS to assist pilots in flight planning.
Briefing items may include weather information, NOTAMs, military activities,
flow control information, and other items as requested. (Refer to AIM)
Pilot In Command -
The pilot responsible for the operation and safety of an aircraft
during flight time. (Refer to FAR Part 91)
Pilots Automatic Telephone Weather Answering Service (PATWAS) -
A continuous telephone recording containing current and forecast
weather information for the pilots. (See Flight Service Station) (Refer
to AIM)
PILOT'S DISCRETION -
When used in conjunction with altitude assignments, means that
ATC has offered the pilot the option of starting climb or descent whenever
he wishes and conducting the climb or descent at any rate he wishes. He
may temporarily level off at any intermediate altitude. However, once he
has vacated an altitude, he may not return to that altitude.
Pilot Weather Report (PIREP) -
A report of meteorological phenomena encountered by aircraft
in flight. (Refer to AIM)
PIREP - (See Pilot Weather Report)
Point Out - (See Radar Point Out)
Polar Track Structure (PTS) -
A system of organized routes between Iceland and Alaska which
overlie Canadian MNPS Airspace.
Position Report -
A report over a known location as transmitted by an aircraft
to ATC. (Refer to AIM)
Position Symbol -
A computer generated indication shown on a radar display to indicate
the mode of tracking.
Practice Instrument Approach -
An instrument approach procedure conducted by a VFR or an IFR
aircraft for the purpose of pilot training or proficiency demonstrations.
Prearranged Coordination -
A standardized procedure which permits an air traffic controller
to enter the airspace assigned to another air traffic controller without
verbal coordination. The procedures are defined in a facility directive
which ensures standard separation between aircraft.
Precipitation -
Any or all forms of water particles (rain, sleet, hail, or snow)
that fall from the atmosphere and reach the surface.
Precision Approach - (See Precision Approach Procedure)
Precision Approach Procedure -
A standard instrument approach procedure in which an electronic
glideslope/glidepath is provided; e.g., ILS/MLS and PAR. (See Instrument
Landing System, Microwave Landing System, Precision Approach Radar)
Precision Approach Radar (PAR) -
Radar equipment in some ATC facilities operated by the FAA and/or
the military services at joint use civil/military locations and separate
military installations to detect and display azimuth, elevations, and range
of aircraft on the final approach course to a runway. This equipment may
be used to monitor certain nonradar approaches, but is primarily used to
conduct a precision instrument approach (PAR) wherein the controller issues
guidance instructions to the pilot based on the aircraft's position in
relation to the final approach course (azimuth), the glidepath (elevation),
and the distance (range) from the touchdown point on the runway as displayed
on the radar scope. (See Glidepath, PAR) (Refer to AIM)
The abbreviation "PAR" is also used to denote preferential arrival
routes in ARTCC computers. (See Preferential Routes) (See [ICAO] Precision
Approach Radar)
[ICAO] Precision Approach Radar (PAR) -
Primary radar equipment used to determine the position of an
aircraft during final approach, in terms of lateral and vertical deviations
relative to a nominal approach path, and in range relative to touchdown.
Note: Precision approach radars are designed to enable
pilots of aircraft to be given guidance by radio communications during
the final stages of the approach to land.
{New-98-3 Revised February 26, 1998}
Precision Runway Monitor (PRM) -
Provides air traffic controllers with high precision secondary
surveillance data for aircraft on final approach to parallel runways that
have extended centerlines separated by less than 4,300 feet. High resolution
color monitoring displays (FMA) are required to present surveillance track
data to controllers along with detailed maps depicting approaches and no
transgression zone.
Preferential Routes -
Preferential routes (PDRs, PARs, and PDARs) are adapted in ARTCC
computers to accomplish inter/intrafacility controller coordination and
to assure that flight data is posted at the proper control positions. Locations
having a need for these specific inbound and out bound routes normally
publish such routes in local facility bulletins, and their use by pilots
minimizes flight plan route amendments. When the workload or traffic situation
permits, controllers normally provide radar vectors or assign requested
routes to minimize circuitous routing. Preferential routes are usually
confined to one ARTCC's area and are referred to by the following names
or acronyms:
{New-98-8 Revised August 13, 1998. "Instrument Departure Procedure
(DP)" was "Standard Instrument Departure (SID)"}
a. Preferential Departure Route (PDR) - A specific departure
route from an airport or terminal area to an enroute point where there
is no further need for flow control. It may be included in a Instrument
Departure Procedure (DP) or Preferred IFR Route.
b. Preferential Arrival Route (PAR) - A specific arrival route
from an appropriate enroute point to an airport or terminal area. It may
be included in a Standard Terminal Arrival (STAR) or Preferred IFR Route.
The abbreviation "PAR" is used primarily within the ARTCC and should not
be confused with the abbreviation for Precision Approach Radar.
c. Preferential Departure and Arrival Route (PDAR) - A route
between two terminals which are within or immediately adjacent to one ARTCC's
area. PDARs are not synonymous with Preferred IFR Routes but may be listed
as such as they do accomplish essentially the same purpose. (See Preferred
IFR Routes, NAS Stage A)
{New-98-8 Revised August 13, 1998}
Preferred IFR Routes -
Routes established between busier airports to increase system
efficiency and capacity. They normally extend through one or more ARTCC
areas and are designed to achieve balanced traffic flows among high density
terminals. IFR clearances are issued on the basis of these routes except
when severe weather avoidance procedures or other factors dictate otherwise.
Preferred IFR Routes are listed in the Airport/Facility Directory. If a
flight is planned to or from an area having such routes but the departure
or arrival point is not listed in the Airport/Facility Directory, pilots
may use that part of a Preferred IFR Route which is appropriate for the
departure or arrival point that is listed. Preferred IFR Routes are correlated
with SIDs and STARs and may be defined by airways, jet routes, direct routes
between NAVAIDs, Waypoints, NAVAID radials/DME, or any combinations thereof.
(See Instrument Departure Procedure, Standard Terminal Arrival, Preferential
Routes, Center's Area) (Refer to Airport/Facility Directory and Notices
to Airmen Publication)
Preflight Pilot Briefing - (See Pilot Briefing)
Prevailing Visibility - (See Visibility)
{New-98-3 Revised February 26, 1998}
PRM -
(See ILS PRM Approach and Precision Runway Monitor)
Procedure Turn (PT) -
The maneuver prescribed when it is necessary to reverse direction
to establish an aircraft on the intermediate approach segment or final
approach course. The outbound course, direction of turn, distance within
which the turn must be completed, and minimum altitude are specified in
the procedure. However, unless otherwise restricted, the point at which
the turn may be commenced and the type and rate of turn are left to the
discretion of the pilot. (See [ICAO] Procedure Turn)
[ICAO] Procedure Turn -
A maneuver in which a turn is made away from a designated track
followed by a turn in the opposite direction to permit the aircraft to
intercept and proceed along the reciprocal of the designated track.
Note 1: Procedure turns are designated "left" or "right"
according to the direction of the initial turn.
Note 2: Procedure turns may be designated as being made
either in level flight or while descending, according to the circumstances
of each individual approach procedure.
Procedure Turn Inbound -
That point of a procedure turn maneuver where course reversal
has been completed and an aircraft is established inbound on the intermediate
approach segment or final approach course. A report of "procedure turn
inbound" is normally used by ATC as a position report for separation purposes.
(See Final Approach Course, Procedure Turn, Segments of an Instrument Approach
Procedure)
Profile Descent -
An uninterrupted descent (except where level flight is required
for speed adjustment; e.g., 250 knots at 10,000 feet MSL) from cruising
altitude/level to interception of a glideslope or to a minimum altitude
specified for the initial or intermediate approach segment of a nonprecision
instrument approach. The profile descent normally terminates at the approach
gate or where the glideslope or other appropriate minimum altitude is intercepted.
Programmable Indicator Data Processor (PIDP) -
The PIDP is a modification to the AN/TPX-42 interrogator system
currently installed in fixed RAPCONs. The PIDP detects, tracks, and predicts
secondary radar aircraft targets. These are displayed by means of computer
generated symbols and alphanumeric characters depicting flight identification,
aircraft altitude, ground speed, and flight plan data. Although primary
radar targets are not tracked, they are displayed coincident with the secondary
radar targets as well as with the other symbols and alphanumerics. The
system has the capability of interfacing with ARTCCs.
Progress Report - (See Position Report)
Progressive Taxi -
Precise taxi instructions given to a pilot unfamiliar with the
airport or issued in stages as the aircraft proceeds along the taxi route.
Prohibited Area - (See Special Use Airspace) (See [ICAO] Prohibited Area)
[ICAO] Prohibited Area -
An airspace of defined dimensions, above the land areas or territorial
waters of a State, within which the flight of aircraft is prohibited.
Proposed Boundary Crossing Time (PBCT) -
Each center has a PBCT parameter for each internal airport. Proposed
internal flight plans are transmitted to the adjacent center if the flight
time along the proposed route from the departure airport to the center
boundary is less than or equal to the value of PBCT or if airport adaptation
specifies transmission regardless of PBCT.
Proposed Departure Time (P Time) -
The time a scheduled flight will depart the gate (scheduled operators)
or the actual runway off time for nonscheduled operators. For EDCT purposes,
the ATCSCC adjusts the "P" time for scheduled operators to reflect the
runway off times.
Protected Airspace -
The airspace on either side of an oceanic route/track that is
equal to one-half the lateral separation minimum except where reduction
of protected airspace has been authorized.
PT - (See Procedure Turn)
PTS - (See Polar Track Structure)
Published Route -
A route for which an IFR altitude has been established and published;
e.g., Federal Airways, Jet Routes, Area Navigation Routes, Specified Direct
Routes.
Q
Queuing - (See Staging/Queuing)
QNE -
The barometric pressure used for the standard altimeter setting
(29.92 inches Hg)
QNH -
The barometric pressure as reported by a particular station.
Quadrant -
A quarter part of a circle, centered on a NAVAID, oriented clockwise
from magnetic north as follows: NE quadrant 000 to 089, SE quadrant 090
to 179, SW quadrant 180 to 269, NW quadrant 270 to 359.
Quick Look -
A feature of NAS Stage A and ARTS which provides the controller
the capability to display full data blocks of tracked aircraft from other
control positions.
Quota Flow Control (QFLOW) -
A flow control procedure by which the Central Flow Control Function
(CFCF) restricts traffic to the ARTC Center area having an impacted airport,
thereby avoiding sector/area saturation. (See Air Traffic Control Systems
Command Center) (Refer to Airport/Facility Directory)
R
Radar -
A device which, by measuring the time interval between transmission
and reception of radio pulses and correlating the angular orientation of
the radiated antenna beam or beams in azimuth and/or elevation, provides
information on range, azimuth, and/or elevation of objects in the path
of the transmitted pulses.
1. Primary Radar - A radar system in which in a minute portion
of a radio pulse transmitted from a site is reflected by an object and
then received back at that site for processing and display at an air traffic
control facility.
2. Secondary Radar/Radar Beacon (ATCRBS) - A radar system in
which the object to be detected is fitted with cooperative equipment in
the form of a radio receiver/transmitter (transponder). Radar pulses transmitted
from the searching transmitter/receiver (interrogator) site are received
in the cooperative equipment and used to trigger a distinctive transmission
from the transponder. This reply transmission rather than a reflected signal,
is then received back at the transmitter/receiver site for processing and
display at an air traffic control facility. (See Transponder, Interrogator)
(Refer to AIM) (See [ICAO] Radar, [ICAO] Primary Radar, [ICAO] Secondary
Radar)
[ICAO] Radar -
A radio detection device which provides information on range,
azimuth and/or elevation objects.
[ICAO] Primary Radar - A radar system which uses reflected radio
signals.
[ICAO] Secondary Radar - A radar system wherein a radio signal
transmitted from a radar station initiates the transmission of a radio
signal from another station.
Radar Advisory -
The provision of advice and information based on radar observations.
(See Advisory Service)
Radar Altimeter - (See Radio Altimeter)
Radar Approach -
An instrument approach procedure which utilizes Precision Approach
Radar (PAR) or Airport Surveillance Radar (ASR). (See Surveillance Approach,
Airport Surveillance Radar, Precision Approach Radar, Instrument Approach
Procedure) (Refer to AIM) (See [ICAO] Radar Approach)
[ICAO] Radar Approach -
An approach, executed by an aircraft, under the direction of
a radar controller.
Radar Approach Control Facility -
A terminal ATC facility that uses radar and nonradar capabilities
to provide approach control services to aircraft arriving, departing, or
transiting airspace controlled by the facility. (See Approach Control Service).
Provides radar ATC services to aircraft operating in the vicinity
of one or more civil and/or military airports in a terminal area. The facility
may provide services of a ground controlled approach (GCA); i.e., ASR and
PAR approaches. A radar approach control facility may be operated by FAA,
USAF, US Army, USN, USMC, or jointly by FAA and a military service. Specific
facility nomenclatures are used for administrative purposes only and are
related to the physical location of the facility and the operating service
generally as follows:
Army Radar Approach Control (ARAC) (Army)
Radar Air Traffic Control Facility (RATCF) (Navy/FAA).
Radar Approach Control (RAPCON) (Air Force/FAA).
Terminal Radar Approach Control (TRACON) (FAA).
Tower/Airport Traffic Control Tower (ATCT) (FAA). (Only those
towers delegated approach control authority.)
Radar Arrival -
An aircraft arriving at an airport served by a radar facility
and in radar contact with the facility. (See Nonradar)
Radar Beacon - (See Radar)
RADAR CONTACT -
1. Used by ATC to inform an aircraft that it is identified on
the radar display and radar flight following will be provided until radar
identification is terminated. Radar service may also be provided within
the limits of necessity and capability. When a pilot is informed of "radar
contact," he automatically discontinues reporting over compulsory reporting
points. (See Radar Flight Following, Radar Contact Lost, Radar Service,
Radar Service Terminated) (Refer to AIM)
2. The term used to inform the controller that the aircraft is
identified and approval is granted for the aircraft to enter the receiving
controllers airspace. (See [ICAO] Radar Contact)
RADAR CONTACT LOST -
Used by ATC to inform a pilot that radar data used to determine
the aircraft's position is no longer being received, or is no longer reliable
and radar service is no longer being provided. The loss may be attributed
to several factors including the aircraft merging with weather or ground
clutter, the aircraft operating below radar line of sight coverage, the
aircraft entering an area of poor radar return, failure of the aircraft
transponder, or failure of the ground radar equipment. (See Clutter, Radar
Contact)
[ICAO] Radar Clutter -
The visual indication on a radar display of unwanted signals.
[ICAO] Radar Contact -
The situation which exists when the radar blip or radar position
symbols of a particular aircraft is seen and identified on a radar display.
Radar Environment -
An area in which radar service may be provided. (See Radar Contact,
Radar Service, Additional Services, Traffic Advisories)
Radar Flight Following -
The observation of the progress of radar identified aircraft,
whose primary navigation is being provided by the pilot, wherein the controller
retains and correlates the aircraft identity with the appropriate target
or target symbol, displayed on the radar scope. (See Radar Contact, Radar
Service) (Refer to AIM)
Radar Identification -
The process of ascertaining that an observed radar target is
the radar return from a particular aircraft. (See Radar Contact, Radar
Service) (See [ICAO] Radar Identification)
[ICAO] Radar Identification -
The process of correlating a particular radar blip or radar position
symbol with a specific aircraft.
Radar Identified Aircraft -
An aircraft, the position of which has been correlated with an
observed target or symbol on the radar display. (See Radar Contact, Radar
Contact Lost)
Radar Monitoring - (See Radar Service)
Radar Navigational Guidance - (See Radar Service)
Radar Point Out -
An action taken by a controller to transfer the radar identification
of an aircraft to another controller if the aircraft will or may enter
the airspace or protected airspace of another controller and radio communications
will not be transferred.
Radar Required -
A term displayed on charts and approach plates and included in
FDC NOTAMs to alert pilots that segments of either an instrument approach
procedure or a route are not navigable because of either the absence or
unusability of a NAVAID. The pilot can expect to be provided radar navigational
guidance while transiting segments labeled with this term. (See Radar Route,
Radar Service)
Radar Route -
A flight path or route over which an aircraft is vectored. Navigational
guidance and altitude assignments are provided by ATC. (See Flight Path,
Route)
Radar Separation - (See Radar Service)
Radar Service -
A term which encompasses one or more of the following services
based on the use of radar which can be provided by a controller to a pilot
of a radar identified aircraft.
1. Radar Monitoring - The radar flight following of aircraft,
whose primary navigation is being performed by the pilot, to observe and
note deviations from its authorized flight path, airway, or route. When
being applied specifically to radar monitoring of instrument approaches;
i.e., with precision approach radar (PAR) or radar monitoring of simultaneous
ILS/MLS approaches, it includes advice and instructions whenever an aircraft
nears or exceeds the prescribed PAR safety limit or simultaneous ILS/MLS
no transgression zone. (See Additional Services, Traffic Advisories)
2. Radar Navigational Guidance - Vectoring aircraft to provide
course guidance.
3. Radar Separation - Radar spacing of aircraft in accordance
with established minima. (See [ICAO] Radar Service)
[ICAO] Radar Service -
Term used to indicate a service provided directly by means of
radar.
[ICAO] Radar Monitoring - The use of radar for the purpose of
providing aircraft with information and advice relative to significant
deviations from nominal flight path.
[ICAO] Radar Separation - The separation used when aircraft position
information is derived from radar sources.
RADAR SERVICE TERMINATED -
Used by ATC to inform a pilot that he will no longer be provided
any of the services that could be received while in radar contact. Radar
service is automatically terminated, and the pilot is not advised in the
following cases:
1. An aircraft cancels its IFR flight plan, except within Class
B airspace, Class C airspace, a TRSA, or where Basic Radar service is provided.
2. An aircraft conducting an instrument, visual, or contact
approach has landed or has been instructed to change to advisory frequency.
3. An arriving VFR aircraft, receiving radar service to a tower
controlled airport within Class B airspace, Class C airspace, a TRSA, or
where sequencing service is provided, has landed; or to all other airports,
is instructed to change to tower or advisory frequency.
4. An aircraft completes a radar approach.
Radar Surveillance -
The radar observation of a given geographical area for the purpose
of performing some radar function.
Radar Traffic Advisories -
Advisories issued to alert pilots to known or observed radar
traffic which may affect the intended route of flight of their aircraft.
(See Traffic Advisories)
Radar Traffic Information Service - (See Traffic Advisories)
[ICAO] Radar Vectoring -
Provision of navigational guidance to aircraft in the form of
specific headings, based on the use of radar.
Radar Weather Echo Intensity Levels -
Existing radar systems cannot detect turbulence. However, there
is a direct correlation between the degree of turbulence and other weather
features associated with thunderstorms and the radar weather echo intensity.
The National Weather Service has categorized radar weather echo intensity
for precipitation into six levels. These levels are sometimes expressed
during communications as "VIP LEVEL" 1 through 6 (derived from the component
of the radar that produces the information - Video Integrator and Processor).
The following list gives the "VIP LEVELS" in relation to the precipitation
intensity within a thunderstorm:
Level 1. WEAK
Level 2. MODERATE
Level 3. STRONG
Level 4. VERY STRONG
Level 5. INTENSE
Level 6. EXTREME
(See AC 00-45)
Radial -
A magnetic bearing extending from a VOR/VORTAC/TACAN navigation
facility.
Radio -
1. A device used for communication.
2. Used to refer to a flight service station; e.g., "Seattle
Radio" is used to call Seattle FSS.
Radio Altimeter -
Aircraft equipment which makes use of the reflection of radio
waves from the ground to determine the height of the aircraft above the
surface.
Radio Beacon - (See Nondirectional Beacon)
Radio Detection And Ranging - (See Radar)
Radio Magnetic Indicator (RMI) -
An aircraft navigational instrument coupled with a gyro compass
or similar compass that indicates the direction of a selected NAVAID and
indicates bearing with respect to the heading of the aircraft.
Ramp - (See Apron)
Random Altitude -
An altitude inappropriate for direction of flight and/or not
in accordance with FAA Order 7110.65, paragraph 4-5-1.
Random Route -
Any route not established or charted/published or not otherwise
available to all users.
RC - (See Road Reconnaissance)
RCAG - (See Remote Communication Air/Ground Facility)
RCC - (See Rescue Coordination Center)
RCO - (See Remote Communications Outlet)
RCR - (See Runway Condition Reading)
READ BACK -
Repeat my message back to me.
{New-98-3 Added February 26, 1998}
Receiver Autonomous Integrity Monitoring (RAIM) -
A technique whereby a civil GNSS receiver/processor determines
the integrity of the GNSS navigation signals without reference to sensors
or non-DoD integrity systems other than the receiver itself. This determination
is achieved by a consistency check among redundant pseudo-range measurements.
Receiving Controller -
A controller/facility receiving control of an aircraft from another
controller/facility.
Receiving Facility - (See Receiving Controller)
Receiver Autonomous Integrity Monitoring (RAIM) -
A technique whereby a civil GNSS receiver/processor determines
the integrity of the GNSS navigation signals without reference to sensors
or non-DoD integrity systems other than the receiver itself. This determination
is achieved by a consistency check among repugnant pseudorange measurements.
REDUCE SPEED TO (SPEED) - (See Speed Adjustment)
REIL - (See Runway End Identifier Lights)
Release Time -
A departure time restriction issued to a pilot by ATC (either
directly or through an authorized relay) when necessary to separate a departing
aircraft from other traffic. (See [ICAO] Release Time)
[ICAO] Release Time -
Time prior to which an aircraft should be given further clearance
or prior to which it should not proceed in case of radio failure.
Remote Communications Air/Ground Facility (RCAG) -
An unmanned VHF/UHF transmitter/receiver facility which is used
to expand ARTCC air/ground communications coverage and to facilitate direct
contact between pilots and controllers. RCAG facilities are sometimes not
equipped with emergency frequencies 121.5 MHz and 243.0 MHz. (Refer to
AIM)
Remote Communications Outlet (RCO) -
An unmanned communications facility remotely controlled by air
traffic personnel. RCOs serve FSSs. RTRs serve terminal ATC facilities.
An RCO or RTR may be UHF or VHF and will extend the communication range
of the air traffic facility. There are several classes of RCOs and RTRs.
The class is determined by the number of transmitters or receivers. Class
A through G are used primarily for air/ground purposes. RCO and RTR class
O facilities are nonprotected outlets subject to undetected and prolonged
outages. RCO (O's) and RTR (O's) where established for the express purpose
of providing ground to ground communications between air traffic control
specialists and pilots located at a satellite airport for delivering enroute
clearances, issuing departure authorizations, and acknowledging instrument
flight rules cancellations or departure/landing times. As a secondary function,
they may be used for advisory purposes whenever the aircraft is below the
coverage of the primary air/ground frequency.
Remote Transmitter/Receiver (RTR) - (See Remote Communications Outlet)
REPORT -
Used to instruct pilots to advise ATC of specified information;
e.g., "Report passing Hamilton VOR."
Reporting Point -
A geographical location in relation to which the position of
an aircraft is reported. (See Compulsory Reporting Points) (Refer to AIM)
(See [ICAO] Reporting Point)
[ICAO] Reporting Point -
A specified geographical location in relation to which the position
of an aircraft can be reported.
REQUEST FULL ROUTE CLEARANCE -
Used by pilots to request that the entire route of flight be
read verbatim in an ATC clearance. Such request should be made to preclude
receiving an ATC clearance based on the original filed flight plan when
a filed IFR flight plan has been revised by the pilot, company, or operations
prior to departure.
Rescue Coordination Center (RCC) -
A search and rescue (SAR) facility equipped and manned to coordinate
and control SAR operations in an area designated by the SAR plan. The U.S.
Coast Guard and the U.S. Air Force have responsibility for the operation
of RCCs. (See [ICAO] Rescue Coordination Centre)
[ICAO] Rescue Coordination Centre -
A unit responsible for promoting efficient organization of search
and rescue service and for coordinating the conduct of search and rescue
operations within a search and rescue region.
Resolution Advisory -
A display indication given to the pilot by the traffic alert
and collision avoidance systems (TCAS II) recommending a maneuver to increase
vertical separation relative to an intruding aircraft. Positive, negative,
and vertical speed limit (VSL) advisories constitute the resolution advisories.
A resolution advisory is also classified as corrective or preventive.
Restricted Area -
(See Special Use Airspace) (See [ICAO] Restricted Area)
[ICAO] Restricted Area -
An airspace of defined dimensions, above the land areas or territorial
waters of a State, within which the flight of aircraft is restricted in
accordance with certain specified conditions.
RESUME OWN NAVIGATION -
Used by ATC to advise a pilot to resume his own navigational
responsibility. It is issued after completion of a radar vector or when
radar contact is lost while the aircraft is being radar vectored. (See
Radar Contact Lost, Radar Service Terminated)
RESUME NORMAL SPEED -
{New-98-3 Revised February 26, 1998}
Used by ATC to advise a pilot that previously issued speed control
restrictions are deleted. An instruction to "resume normal speed" does
not delete speed restrictions that are applicable to published procedures
of upcoming segments of flight, unless specifically stated by ATC. This
does not relieve the pilot of those speed restrictions which are applicable
to FAR 91.117.
RMI - (See Radio Magnetic Indicator)
RNAV - (See Area Navigation)
[ICAO] RNAV - (See [ICAO] Area Navigation)
RNAV Approach -
An instrument approach procedure which relies on aircraft area
navigation equipment for navigational guidance. (See Instrument Approach
Procedure, Area Navigation)
Road Reconnaissance (RC) -
Military activity requiring navigation along roads, railroads,
and rivers. Reconnaissance route/route segments are seldom along a straight
line and normally require a lateral route width of 10 NM to 30 NM and an
altitude range of 500 feet to 10,000 feet AGL.
ROGER -
I have received all of your last transmission. It should not
be used to answer a question requiring a yes or a no answer. (See Affirmative,
Negative)
Rollout RVR - (See Visibility)
Route -
A defined path, consisting of one or more courses in a horizontal
plane, which aircraft traverse over the surface of the earth. (See Airway,
Jet Route, Published Route, Unpublished Route)
Route Segment -
As used in Air Traffic Control, a part of a route that can be
defined by two navigational fixes, two NAVAIDs or a fix and a NAVAID. (See
Fix, Route) (See [ICAO] Route Segment)
[ICAO] Route Segment -
A portion of a route to be flown, as defined by two consecutive
significant points specified in a flight plan.
RSA - (See Runway Safety Area)
RTR - (See Remote Transmitter/Receiver)
Runway -
A defined rectangular area on a land airport prepared for the
landing and takeoff run of aircraft along its length. Runways are normally
numbered in relation to their magnetic direction rounded off to the nearest
10 degrees; e.g., Runway 01, Runway 25. (See Parallel Runways) (See [ICAO]
Runway)
[ICAO] Runway -
A defined rectangular area on a land aerodrome prepared for the
landing and takeoff of aircraft.
Runway Centerline Lighting - (See Airport Lighting)
Runway Condition Reading (RCR) -
Numerical decelerometer readings relayed by air traffic controllers
at USAF and certain civil bases for use by the pilot in determining runway
braking action. These readings are routinely relayed only to USAF and Air
National Guard Aircraft. (See Braking Action)
Runway End Identifier Lights (REIL) - (See Airport Lighting)
Runway Gradient -
The average slope, measured in percent, between two ends or points
on a runway. Runway gradient is depicted on Government aerodrome sketches
when total runway gradient exceeds 0.3%.
RUNWAY HEADING -
The magnetic direction that corresponds with the runway centerline
extended, not the painted runway number. When cleared to "fly or maintain
runway heading," pilots are expected to fly or maintain the heading that
corresponds with the extended centerline of the departure runway. Drift
correction shall not be applied; e.g., Runway 4, actual magnetic heading
of the runway centerline 044, fly 044.
Runway In Use/Active Runway/Duty Runway -
Any runway or runways currently being used for takeoff or landing.
When multiple runways are used, they are all considered active runways.
In the metering sense, a selectable adapted item which specifies the landing
runway configuration or direction of traffic flow. The adapted optimum
flight plan from each transition fix to the vertex is determined by the
runway configuration for arrival metering processing purposes.
Runway Lights - (See Airport Lighting)
Runway Markings - (See Airport Marking Aids)
Runway Overrun -
In military aviation exclusively, a stabilized or paved area
beyond the end of a runway, of the same width as the runway plus shoulders,
centered on the extended runway centerline.
Runway Profile Descent -
An instrument flight rules (IFR) air traffic control arrival
procedure to a runway published for pilot use in graphic and/or textual
form and may be associated with a STAR. Runway Profile Descents provide
routing and may depict crossing altitudes, speed restrictions, and headings
to be flown from the enroute structure to the point where the pilot will
receive clearance for and execute an instrument approach procedure. A Runway
Profile Descent may apply to more than one runway if so stated on the chart.
(Refer to AIM)
Runway Safety Area (RSA) -
A defined surface surrounding the runway prepared, or suitable,
for reducing the risk of damage to airplanes in the event of an undershoot,
overshoot, or excursion from the runway. The dimensions of the RSA vary
and can be determined by using the criteria contained within Advisory Circular
150/5300-13, Chapter 3. Figure 3-1 in Advisory Circular 150/5300-13 depicts
the RSA. The design standards dictate that the RSA shall be:
1. Cleared, graded, and have no potentially hazardous ruts,
humps, depressions, or other surface variations;
2. Drained by grading or storm sewers to prevent water accumulation;
3. Capable, under dry conditions, of supporting snow removal
equipment, aircraft rescue and firefighting equipment, and the occasional
passage of aircraft without causing structural damage to the aircraft;
and,
4. Free of objects, except for objects that need to be located
in the runway safety area because of their function. These objects shall
be constructed on low impact resistant supports (frangible mounted structures)
to the lowest practical height with the frangible point to higher than
3 inches above grade.
(Refer to AC 150/5300-13, Chapter 3.)
Runway Use Program -
A noise abatement runway selection plan designed to enhance noise
abatement efforts with regard to airport communities for arriving and departing
aircraft. These plans are developed into runway use programs and apply
to all turbojet aircraft 12,500 pounds or heavier; turbojet aircraft less
than 12,500 pounds are included only if the airport proprietor determines
that the aircraft creates a noise problem. Runway use programs are coordinated
with FAA offices, and safety criteria used in these programs are developed
by the Office of Flight Operations. Runway use programs are administered
by the Air Traffic Service as "Formal" or "Informal" programs.
1. Formal Runway Use Program - An approved noise abatement program
which is defined and acknowledged in a Letter of Understanding between
Flight Operations, Air Traffic Service, the airport proprietor, and the
users. Once established, participation in the program is mandatory for
aircraft operators and pilots as provided for in FAR 91.87.
2. Informal Runway Use Program - An approved noise abatement
program which does not require a Letter of Understanding, and participation
in the program is voluntary for aircraft operators/pilots.
Runway Visibility Value - (See Visibility)
Runway Visual Range - (See Visibility)
S
Safety Alert -
A safety alert issued by ATC to aircraft under their control
if ATC is aware the aircraft is at an altitude which, in the controller's
judgment, places the aircraft in unsafe proximity to terrain, obstructions,
or other aircraft. The controller may discontinue the issuance of further
alerts if the pilot advises he is taking action to correct the situation
or has the other aircraft in sight.
1. Terrain/Obstruction Alert - A safety alert issued by ATC
to aircraft under their control if ATC is aware the aircraft is at an altitude
which, in the controller's judgment, places the aircraft in unsafe proximity
to terrain/obstructions, e.g., "Low Altitude Alert, check your altitude
immediately."
2. Aircraft Conflict Alert - A safety alert is issued by ATC
to aircraft under their control if ATC is aware of an aircraft that is
not under their control at an altitude which, in the controller's judgment,
places both aircraft in unsafe proximity to each other. With the alert,
ATC will offer the pilot an alternate course of action when feasible; e.g.,
"Traffic Alert, advise you turn right heading zero niner zero or climb
to eight thousand immediately."
The issuance of a safety alert is contingent upon the capability
of the controller to have an awareness of an unsafe condition. The course
of action provided will be predicated on other traffic under ATC control.
Once the alert is issued, it is solely the pilot's prerogative to determine
what course of action, if any, he will take.
Sail Back -
A maneuver during high wind conditions (usually with power off)
where float plane movement is controlled by water rudders or opening and
closing cabin doors.
Same Direction Aircraft -
Aircraft are operating in the same direction when:
1. They are following the same track in the same direction;
or
2. Their tracks are parallel and the aircraft are flying in
the same direction; or
3. Their tracks intersect at an angle of less than 45 degrees.
SAR - (See Search And Rescue)
SAY AGAIN -
Used to request a repeat of the last transmission. Usually specifies
transmission or portion thereof not understood or received; e.g., "Say
again all after ABRAM VOR."
SAY ALTITUDE -
Used by ATC to ascertain an aircraft's specific altitude/flight
level. When the aircraft is climbing or descending, the pilot should state
the indicated altitude rounded to the nearest 100 feet.
SAY HEADING -
Used by ATC to request an aircraft heading. The pilot should
state the actual heading of the aircraft.
SDF - (See Simplified Directional Facility)
Sea Lane -
A designated portion of water outlined by visual surface markers
for and intended to be used by aircraft designed to operate on water.
Search And Rescue (SAR) -
A service which seeks missing aircraft and assists those found
to be in need of assistance. It is a cooperative effort using the facilities
and services of available Federal, state and local agencies. The U.S. Coast
Guard is responsible for coordination of search and rescue for the Maritime
Region, and the U.S. Air Force is responsible for search and rescue for
the Inland Region. Information pertinent to search and rescue should be
passed through any air traffic facility or be transmitted directly to the
Rescue Coordination Center by telephone. (See Flight Service Station, Rescue
Coordination Center) (Refer to AIM)
Search And Rescue Facility -
A facility responsible for maintaining and operating a search
and rescue (SAR) service to render aid to persons and property in distress.
It is any SAR unit, station, NET, or other operational activity which can
be usefully employed during an SAR Mission; e.g., a Civil Air Patrol Wing,
or a Coast Guard Station. (See Search and Rescue)
Sectional Aeronautical Charts -
(See Aeronautical Chart)
Sector List Drop Interval (SLDI) -
A parameter number of minutes after the meter fix time when arrival
aircraft will be deleted from the arrival sector list.
See And Avoid -
When weather conditions permit, pilots operating IFR or VFR are
required to observe and maneuver to avoid other aircraft. Right-of-way
rules are contained in Part 91.
See And Avoid -
A visual procedure where in pilots of aircraft flying in visual
meteorological conditions (VMC), regardless of type of flight plan, are
charged with the responsibility to observe the presence of other aircraft
and to maneuver their aircraft as required to avoid the other aircraft.
Right of way rules are contained in FAR Part 91. (See Instrument Flight
Rules, Visual Flight Rules, Visual Meteorological Conditions, Instrument
Meteorological Conditions)
Segmented Circle -
A system of visual indicators designed to provide traffic pattern
information at airports without operating control towers. (Refer to AIM)
Segments of an Instrument Approach Procedure -
An instrument approach procedure may have as many as four separate
segments depending on how the approach procedure is structured.
1. Initial Approach - The segment between the initial approach
fix and the intermediate fix or the point where the aircraft is established
on the intermediate course or final approach course. (See [ICAO] Initial
Approach Segment)
2. Intermediate Approach - The segment between the intermediate
fix or point and the final approach fix. (See [ICAO] Intermediate Approach
Segment)
3. Final Approach - The segment between the final approach fix
or point and the runway, airport, or missed approach point. (See [ICAO]
Final Approach Segment)
4. Missed Approach - The segment between the missed approach
point or the point of arrival at decision height and the missed approach
fix at the prescribed altitude. (Refer to FAR Part 97) (See [ICAO] Missed
Approach Procedure)
Selected Ground Delays -
A traffic management procedure whereby selected flights are issued
ground delays to better regulate traffic flows over a particular fix or
area.
Separation -
In air traffic control, the spacing of aircraft to achieve their
safe and orderly movement in flight and while landing and taking off. (See
Separation Minima) (See [ICAO] Separation)
[ICAO] Separation -
Spacing between aircraft, levels or tracks.
Separation Minima -
The minimum longitudinal, lateral, or vertical distances by which
aircraft are spaced through the application of air traffic control procedures.
(See Separation)
Service -
A generic term that designates functions or assistance available
from or rendered by air traffic control. For example, Class C service would
denote the ATC services provided within a Class C airspace area.
Severe Weather Avoidance Plan (SWAP) -
An approved plan to minimize the affect of severe weather on
traffic flows in impacted terminal and/or ARTCC areas. SWAP is normally
implemented to provide the least disruption to the ATC system when flight
through portions of airspace is difficult or impossible due to severe weather.
Severe Weather Forecast Alerts (AWW) -
Preliminary messages issued in order to alert users that a Severe
Weather Watch Bulletin (WW) is being issued. These messages define areas
of possible severe thunderstorms or tornado activity. The messages are
unscheduled and issued as required by the National Severe Storm Forecast
Center at Kansas City, Missouri. (See SIGMET, Convective SIGMET, CWA, AIRMET)
SFA - (See Single Frequency Approach)
SFO - (See Simulated Flame Out)
SHF - (See Super High Frequency)
Short Range Clearance -
A clearance issued to a departing IFR flight which authorizes
IFR flight to a specific fix short of the destination while air traffic
control facilities are coordinating and obtaining the complete clearance.
Short Takeoff And Landing Aircraft (STOL) -
An aircraft which, at some weight within its approved operating
weight, is capable of operating from a STOL runway in compliance with the
applicable STOL characteristics, airworthiness, operations, noise, and
pollution standards. (See Vertical Takeoff and Landing Aircraft)
SIAP - (See Standard Instrument Approach Procedure)
Sidestep Maneuver -
A visual maneuver accomplished by a pilot at the completion of
an instrument approach to permit a straight-in landing on a parallel runway
not more than 1,200 feet to either side of the runway to which the instrument
approach was conducted. (Refer to AIM)
SIGMET -
A weather advisory issued concerning weather significant to the
safety of all aircraft. SIGMET advisories cover severe and extreme turbulence,
severe icing, and widespread dust or sandstorms that reduce visibility
to less than 3 miles. (See AWW, Convective SIGMET, CWA, and AIRMET) (Refer
to AIM) (See [ICAO] SIGMET Information)
[ICAO] SIGMET Information -
Information issued by a meteorological watch office concerning
the occurrence or expected occurrence of specified enroute weather phenomena
which may affect the safety of aircraft operations.
SIGNIFICANT METEOROLOGICAL INFORMATION - (See SIGMET)
Significant Point -
A point, whether a named intersection, a NAVAID, a fix derived
from a NAVAID(s), or geographical coordinate expressed in degrees of latitude
and longitude, which is established for the purpose of providing separation,
as a reporting point, or to delineate a route of flight.
Simplified Directional Facility (SDF) -
A NAVAID used for nonprecision instrument approaches. The final
approach course is similar to that of an ILS localizer except that the
SDF course may be offset from the runway, generally not more than 3 degrees,
and the course may be wider than the localizer, resulting in a lower degree
of accuracy. (Refer to AIM)
Simulated Flameout -
A practice approach by a jet aircraft (normally military) at
idle thrust to a runway. The approach may start at a runway (high key)
and may continue on a relatively high and wide down wind leg with a continuous
turn to final. It terminates in landing or low approach. The purpose of
this approach is to simulate a flameout. (See Flameout)
Simultaneous ILS Approaches -
An approach system permitting simultaneous ILS/MLS approaches
to airports having parallel runways separated by at least 4,300 feet between
centerlines. Integral parts of a total system are ILS/MLS, radar, communications.
ATC procedures, and appropriate airborne equipment. (See Parallel Runways)
(Refer to AIM)
Simultaneous MLS Approaches - (See Simultaneous ILS Approaches)
Single Direction Routes -
Preferred IFR Routes which are sometimes depicted on high altitude
en route charts and which are normally flown in one direction only.
Simultaneous Operations on Intersecting Runways -
Operations which include simultaneous takeoffs and landings and/or
simultaneous landings when a landing aircraft is able and is instructed
by the controller to hold short of the intersecting runway or designated
hold short point. Pilots are expected to promptly inform the controller
if the hold short clearance cannot be accepted. (See Parallel Runways)
(Refer to AIM)
Single Direction Routes -
Preferred IFR Routes which are sometimes depicted on high altitude
enroute charts and which are normally flown in one direction only. (See
Preferred IFR Route) (Refer to Airport/Facility Directory)
Single Frequency Approach (SFA) -
A service provided under a letter of agreement to military single
piloted turbojet aircraft which permits use of a single UHF frequency during
approach for landing. Pilots will not normally be required to change frequency
from the beginning of the approach to touchdown except that pilots conducting
an enroute descent are required to change frequency when control is transferred
from the air route traffic control center to the terminal facility. The
abbreviation "SFA" in the DOD FLIP IFR Supplement under "Communications"
indicates this service is available at an aerodrome.
Single Piloted Aircraft -
A military turbojet aircraft possessing one set of flight controls,
tandem cockpits, or two sets of flight controls but operated by one pilot
is considered single piloted by ATC when determining the appropriate air
traffic service to be applied. (See Single Frequency Approach)
Slash -
A radar beacon reply displayed as an elongated target.
SLDI - (See Sector List Drop Interval)
Slot Time - (See Meter Fix Time/Slot Time)
Slow Taxi -
To taxi a float plane at low power or low RPM.
SN - (See System Strategic Navigation)
SPEAK SLOWER -
Used in verbal communications as a request to reduce speech rate.
Special Emergency -
A condition of air piracy or other hostile act by a person(s)
aboard an aircraft which threatens the safety of the aircraft or its passengers.
Special Instrument Approach Procedure - (See Instrument Approach Procedure)
Special Use Airspace -
Airspace of defined dimensions identified by an area on the surface
of the earth wherein activities must be confined because of their nature
and/or wherein limitations may be imposed upon aircraft operations that
are not a part of those activities. Types of special use airspace are:
a. Alert Area - Airspace which may contain a high volume of
pilot training activities or an unusual type of aerial activity, neither
of which is hazardous to aircraft. Alert Areas are depicted on aeronautical
charts for the information of nonparticipating pilots. All activities within
an Alert Area are conducted in accordance with Federal Aviation Regulations,
and pilots of participating aircraft as well as pilots transiting the area
are equally responsible for collision avoidance.
b. Controlled Firing Area - Airspace wherein activities are
conducted under conditions so controlled as to eliminate hazards to nonparticipating
aircraft and to ensure the safety of persons and property on the ground.
c. Military Operations Area (MOA) - An MOA is airspace established
outside of Class A airspace area to separate or segregate certain nonhazardous
military activities from IFR traffic and to identify for VFR traffic where
these activities are conducted. (Refer to AIM)
d. Prohibited Area - Airspace designated under part 73 within
which no person may operate an aircraft without the permission of the using
agency. (Refer to Enroute Charts, AIM)
e. Restricted Area - Airspace designated under FAR Part 73,
within which the flight of aircraft, while not wholly prohibited, is subject
to restriction. Most restricted areas are designated joint use and IFR/VFR
operations in the area may be authorized by the controlling ATC facility
when it is not being utilized by the using agency. Restricted areas are
depicted on enroute charts. Where joint use is authorized, the name of
the ATC controlling facility is also shown. (Refer to FAR Part 73 and AIM)
f. Warning Area - A warning area is airspace of defined dimensions
extending from 3 nautical miles outward from the coast of the United States,
that contains activity that may be hazardous to nonparticipating aircraft.
The purpose of such warning area is to warn nonparticipating pilots of
the potential danger. A warning area may be located over domestic or international
waters or both.
Special VFR Conditions -
Meteorological conditions that are less than those required for
basic VFR flight in Class B, C, D, or E surface areas and in which some
aircraft are permitted flight under visual flight rules. (See Special VFR
Operations) (Refer to FAR Part 91)
[ICAO] Special VFR Flight -
A VFR flight cleared by air traffic control to operate within
Class B, C, D, and E surface areas in meteorological conditions below VMC.
Special VFR Operations -
Aircraft operating in accordance with clearances within Class
B, C, D, and E surface areas in weather conditions less than the basic
VFR weather minima. Such operations must be requested by the pilot and
approved by ATC. (See Special VFR Conditions) (See [ICAO] Special VFR Flight)
Speed - (See Airspeed, Ground Speed)
Speed Adjustment -
An ATC procedure used to request pilots to adjust aircraft speed
to a specific value for the purpose of providing desired spacing. Pilots
are expected to maintain a speed of plus or minus 10 knots or 0.02 mach
number of the specified speed.
Examples of speed adjustments are:
1. "Increase/reduce speed to mach point (number)."
2. "Increase/reduce speed to (speed in knots)" or "Increase/reduce
speed (number of knots) knots."
Speed Brakes -
Moveable aerodynamic devices on aircraft that reduce airspeed
during descent and landing.
Speed Segments -
Portions of the arrival route between the transition point and
the vertex along the optimum flight path for which speeds and altitudes
are specified. There is one set of arrival speed segments adapted from
each transition point to each vertex. Each set may contain up to six segments.
SQUAWK (Mode, Code, Function) -
Activate specific modes/codes/functions on the aircraft transponder,
e.g., "Squawk three/alfa, two one zero five, low." (See Transponder)
Staging/Queuing -
The placement, integration, and segregation of departure aircraft
in designated movement areas of an airport by departure fix, EDCT, and/or
restriction.
Standard Instrument Approach Procedure (SIAP) - (See Instrument Approach Procedure)
Standard Rate Turn -
A turn of three degrees per second.
Standard Terminal Arrival (STAR) -
A preplanned instrument flight rule (IFR) air traffic control
arrival procedure published for pilot use in graphic and/or textual form.
STARs provide transition from the enroute structure to an outer fix or
an instrument approach fix/arrival waypoint in the terminal area.
Standard Terminal Arrival Charts -
(See Aeronautical Chart)
STAND BY -
Means the controller or pilot must pause for a few seconds, usually
to attend to other duties of a higher priority. Also means to wait as in
"stand by for clearance." The caller should reestablish contact if a delay
is lengthy. "Stand by" is not an approval or denial.
STAR - (See Standard Terminal Arrival)
State Aircraft -
Aircraft used in military, customs and police service, in the
exclusive service of any government, or of any political subdivision, thereof
including the government of any state, territory, or possession of the
United States or the District of Columbia, but not including any government-owned
aircraft engaged in carrying persons or property for commercial purposes.
Static Restrictions -
Those restrictions that are usually not subject to change, fixed,
in place, and/or published.
Stationary Reservations -
Altitude reservations which encompass activities in a fixed area.
Stationary reservations may include activities, such as special tests of
weapons systems or equipment, certain U.S. Navy carrier, fleet, and antisubmarine
operations, rocket, missile and drone operations, and certain aerial refueling
or similar operations.
Stepdown Fix -
A fix permitting additional descent within a segment of an instrument
approach procedure by identifying a point at which a controlling obstacle
has been safely overflown.
Step Taxi -
To taxi a float plane at full power or high RPM.
Step Turn -
A maneuver used to put a float plane in a planing configuration
prior to entering an active sea lane for takeoff. The STEP TURN maneuver
should only be used upon pilot request.
Stereo Route -
A routinely used route of flight established by users and ARTCCs
identified by a coded name; e.g., ALPHA 2. These routes minimize flight
plan handling and communications.
STOL Aircraft - (See Short Takeoff And Landing Aircraft)
STOP ALTITUDE SQUAWK -
Used by ATC to inform an aircraft to turn off the automatic altitude
reporting feature of its transponder. It is issued when the verbally reported
altitude varies 300 feet or more from the automatic altitude report. (See
Altitude Readout, Transponder)
Stop-and-Go
A procedure wherein an aircraft will land, make a complete stop
on the runway, and then commence a takeoff from that point. (See Low Approach,
Option Approach)
STOP BURST - (See Stop Stream)
STOP BUZZER - (See Stop Stream)
Stopover Flight Plan -
A flight plan format which permits in a single submission the
filing of a sequence of flight plans through interim full stop destinations
to a final destination.
STOP SQUAWK (Mode or Code) -
Used by ATC to tell the pilot to turn specified functions of
the aircraft transponder off. (See Stop Altitude Squawk, Transponder)
STOP STREAM -
Used by ATC to request a pilot to suspend electronic countermeasure
activity. (See Jamming)
Stopway -
An area beyond the takeoff runway no less wide than the runway
and centered upon the extended centerline of the runway, able to support
the airplane during an aborted takeoff, without causing structural damage
to the airplane, and designated by the airport authorities for use in decelerating
the airplane during an aborted takeoff.
Straight-in Approach - IFR -
An instrument approach wherein final approach is begun without
first having executed a procedure turn, not necessarily completed with
a straight-in landing or made to straight-in landing minimums.
(See Straight-in landing).
(See Landing Minimums).
(See Straight-in Approach - VFR).
Straight-in Approach - VFR -
Entry into the traffic pattern by interception of the extended
runway centerline (final approach course) without executing any other portion
of the traffic pattern. (See Traffic Pattern)
Straight-in Landing -
A landing made on a runway aligned within 30 degrees of the final
approach course following completion of an instrument approach. (See Straight-in
Approach - IFR)
Straight-in Landing Minimums - (See Landing Minimums)
Straight-in Minimums - (See Straight-In Landing Minimums)
Substitutions -
Users are permitted to exchange CTAs. Normally, the airline dispatcher
will contact the ATCSCC with this request. The ATCSCC shall forward approved
substitutions to the TMUs who will notify the appropriate terminals. Permissible
swapping must not change the traffic load for any given hour of an EQF
program.
Substitute Route -
A route assigned to pilots when any part of an airway or route
is unusable because of NAVAID status. These routes consist of:
1. Substitute routes which are shown on U.S. Government charts.
2. Routes defined by ATC as specific NAVAID radials or courses.
3. Routes defined by ATC as direct to or between NAVAIDs.
Sunset And Sunrise -
The mean solar times of sunset and sunrise as published in the
Nautical Almanac, converted to local standard time for the locality concerned.
Within Alaska, the end of evening civil twilight and the beginning of morning
civil twilight, as defined for each locality.
Super High Frequency (SHF) -
The frequency band between 3 and 30 gigahertz (GHz). The elevation
and azimuth stations of the microwave landing system operate from 5031
MHz to 5091 MHz in this spectrum.
Supplemental Weather Service Location -
Airport facilities staffed with contract personnel who take weather
observations and provide current local weather to pilots via telephone
or radio. (All other services are provided by the parent FSS).
SUPPS -
Refers to ICAO Document 7030 Regional Supplementary Procedures.
SUPPS contain procedures for each ICAO Region which are unique to that
Region and are not covered in the worldwide provisions identified in the
ICAO Air Navigation Plan. Procedures contained in chapter 8 are based in
part on those published in SUPPS.
Surface Area -
The airspace contained by the lateral boundary of the Class B,
C, D, or E airspace designated for an airport that begins at the surface
and extends upward.
SURPIC (Surface Picture) -
A description of surface vessels in the area of a Search and
Rescue incident including their predicted positions and their characteristics.
(See FAA Order 7110.65, Paragraph 10-7-4, In-Flight Contingencies).
Surveillance Approach -
An instrument approach wherein the air traffic controller issues
instructions, for pilot compliance, based on aircraft position in relation
to the final approach course (azimuth), and the distance (range) from the
end of the runway as displayed on the controller's radar scope. The controller
will provide recommended altitudes on final approach if requested by the
pilot. (Refer to AIM)
SWAP - (See Severe Weather Avoidance Plan)
SWSL - (See Supplemental Weather Service Location)
System Strategic Navigation (SN) -
Military activity accomplished by navigating along a preplanned
route using internal aircraft systems to maintain a desired track. This
activity normally requires a lateral route width of 10 NM and altitude
range of 1,000 feet to 6,000 feet AGL with some route segments that permit
terrain following.
T
TACAN - (See Tactical Air Navigation)
TACAN-Only Aircraft -
An aircraft, normally military, possessing TACAN with DME but
no VOR navigational system capability. Clearances must specify TACAN or
VORTAC fixes and approaches.
Tactical Air Navigation (TACAN) -
An ultra high frequency electronic rho-theta air navigation aid
which provides suitably equipped aircraft a continuous indication of bearing
and distance to the TACAN station. (See VORTAC) (Refer to AIM)
Tailwind -
Any wind more than 90 degrees to the longitudinal axis of the
runway. The magnetic direction of the runway shall be used as the basis
for determining the longitudinal axis.
TAKEOFF AREA - (See Landing Area)
[ICAO] Takeoff Distance Available (TODA) -
The length of the takeoff run available plus the length of the
clearway, if provided.
[ICAO] Takeoff Run Available (TORA) -
The length of runway declared available and suitable for the
ground run of an aeroplane takeoff.
Target -
The indication shown on a radar display resulting from a primary
radar return or a radar beacon reply. (See Radar, Target Symbol) (See [ICAO]
Target)
[ICAO] Target -
In radar:
1. Generally, any discrete object which reflects or retransmits
energy back to the radar equipment.
2. Specifically, an object of radar search or surveillance.
Target Resolution -
A process to insure that correlated radar targets do not touch.
Target resolution shall be applied as follows:
1. Between the edges of two primary targets or the edges of
the ASR-9 primary target symbol.
2. Between the end of the beacon control slash and the edge
of a primary target.
3. Between the ends of two beacon control slashes.
MANDATORY TRAFFIC ADVISORIES AND SAFETY ALERTS SHALL BE ISSUED
WHEN THIS PROCEDURE IS USED.
Note: This procedure shall not be provided utilizing mosaic
radar systems.
Target Symbol -
A computer generated indication shown on a radar display resulting
from a primary radar return or a radar beacon reply.
Taxi -
The movement of an airplane under its own power on the surface
of an airport (FAR 135.100 Note). Also, it describes the surface movement
of helicopters equipped with wheels. (See Air Taxi, Hover Taxi) (Refer
to AIM) (Refer to FAR 135.100)
TAXI INTO POSITION AND HOLD -
Used by ATC to inform a pilot to taxi onto the departure runway
in takeoff position and hold. It is not authorization for takeoff. It is
used when takeoff clearance cannot immediately be issued because of traffic
or other reasons. (See Cleared for Takeoff)
Taxi Patterns -
Patterns established to illustrate the desired flow of ground
traffic for the different runways or airport areas available for use.
TCAS - (See Traffic Alert and Collision Avoidance System)
TCH - (See Threshold Crossing Height)
TCLT - (See Tentative Calculated Landing Time)
TDZE - (See Touchdown Zone Elevation)
Telephone Information Briefing Service (TIBS) -
A continuous telephone recording of meteorological and/or aeronautical
information. (Refer to AIM)
Tentative Calculated Landing Time (TCLT) -
A projected time calculated for adapted vertex for each arrival
aircraft based upon runway configuration, airport acceptance rate, airport
arrival delay period, and other metered arrival aircraft. This time is
either the VTA of the aircraft or the TCLT/ACLT of the previous aircraft
plus the AAI, whichever is later. This time will be updated in response
to an aircraft's progress and its current relationship to other arrivals.
Terminal Area -
A general term used to describe airspace in which approach control
service or airport traffic control service is provided.
Terminal Area Facility -
A facility providing air traffic control service for arriving
and departing IFR, VFR, Special VFR, and on occasion enroute aircraft.
(See Approach Control Facility, Tower)
Terminal VFR Radar Service -
A national program instituted to extend the terminal radar services
provided instrument flight rules (IFR) aircraft to visual flight rules
(VFR) aircraft. The program is divided into four types of service referred
to as basic radar service, terminal radar service area (TRSA) service,
Class B service and Class C service. The type of service provided at a
particular location is contained in the Airport/Facility Directory.
1. Basic Radar Service: These services are provided for VFR
aircraft by all commissioned terminal radar facilities. Basic radar service
includes safety alerts, traffic advisories, limited radar vectoring when
requested by the pilot, and sequencing at locations where procedures have
been established for this purpose and/or when covered by a letter of agreement.
The purpose of this service is to adjust the flow of arriving IFR and VFR
aircraft into the traffic pattern in a safe and orderly manner and to provide
traffic advisories to departing VFR aircraft.
2. TRSA Service: This service provides, in addition to basic
radar service, sequencing of all IFR and participating VFR aircraft to
the primary airport and separation between all participating VFR aircraft.
The purpose of this service is to provide separation between all participating
VFR aircraft and all IFR aircraft operating within the area defined as
a TRSA.
3. Class C Service: This service provides, in addition to basic
radar service, approved separation between IFR and VFR aircraft, and sequencing
of VFR aircraft, and sequencing of VFR arrivals to the primary airport.
4. Class B Service: This service provides, in addition to basic
radar service, approved separation of aircraft based on IFR, VFR, and/or
weight, and sequencing of VFR arrivals to the primary airport(s).
(See Controlled Airspace, Terminal Radar Service Area) (Refer to AIM, Airport/Facility Directory)
Terminal Radar Service Area (TRSA) -
Airspace surrounding designated airports wherein ATC provides
radar vectoring, sequencing, and separation on a full-time basis for all
IFR and participating VFR aircraft. Service provided in a TRSA is called
Stage III Service. The AIM contains an explanation of TRSA. TRSAs are depicted
on VFR aeronautical charts. Pilot participation is urged but is not mandatory.
(See Terminal Radar Program) (Refer to AIM, Airport/Facility Directory)
Terminal - Very High Frequency Omnidirectional Range Station (TVOR)
-
A very high frequency terminal omnirange station located on or
near an airport and used as an approach aid. (See Navigational Aid, VOR)
Terrain Following (TF) -
The flight of a military aircraft maintaining a constant AGL
altitude above the terrain or the highest obstruction. The altitude of
the aircraft will constantly change with the varying terrain and/or obstruction.
Tetrahedron -
A device normally located on uncontrolled airports and used as
a landing direction indicator. The small end of a tetrahedron points in
the direction of landing. At controlled airports, the tetrahedron, if installed,
should be disregarded because tower instructions supersede the indicator.
(See Segmented Circle) (Refer to AIM)
TF - (See Terrain Following)
THAT IS CORRECT -
The understanding you have is right.
360 Overhead - (See Overhead Approach)
Threshold -
The beginning of that portion of the runway usable for landing.
(See Airport Lighting, Displaced Threshold)
Threshold Crossing Height (TCH) -
The theoretical height above the runway threshold at which the
aircraft's glideslope antenna would be if the aircraft maintains the trajectory
established by the mean ILS glideslope or MLS glidepath. (See Glideslope,
Threshold)
Threshold Lights - (See Airport Lighting)
TIBS - (See Telephone Information Briefing Service)
Time Group -
Four digits representing the hour and minutes from the Coordinated
Universal Time (UTC) clock. FAA uses UTC for all operations. The term "Zulu"
may be used to denote UTC. The word "local" or the time zone equivalent
shall be used to denote local when local time is given during radio and
telephone communications. When written, a time zone designator is used
to indicate local time; e.g. "0205M" (Mountain). The local time may be
based on the 24-hour clock system. The day begins at 0000 and ends at 2359.
TMPA - (See Traffic Management Program Alert)
TMU - (See Traffic Management Unit)
[ICAO] TODA - (See Takeoff Distance Available)
[ICAO] TORA - (See Takeoff Run Available)
Torching -
The burning of fuel at the end of an exhaust pipe or stack of
a reciprocating aircraft engine, the result of an excessive richness in
the fuel air mixture.
[ICAO] Total Estimated Elapsed Time -
For IFR flights, the estimated time required from takeoff to
arrive over the designated point, defined by reference to navigation aids,
from which it is intended that an instrument approach procedure will be
commenced, or, if no navigation aid is associated with the destination
aerodrome, to arrive over the destination aerodrome. For VFR flights, the
estimated time required from takeoff to arrive over the destination aerodrome.
(See Estimated Elapsed Time)
Touch-And-Go -
An operation by an aircraft that lands and departs on a runway
without stopping or exiting the runway.
Touch-And-Go Landing - (See Touch And Go)
Touchdown -
1. The point at which an aircraft first makes contact with the
landing surface.
2. Concerning a precision radar approach (PAR), it is the point
where the glidepath intercepts the landing surface.
(See [ICAO] Touchdown)
[ICAO] Touchdown -
The point where the nominal glidepath intercepts the runway.
Note: Touchdown as defined above is only a datum and is
not necessarily the actual point at which the aircraft will touch the runway.
Touchdown RVR - (See Visibility)
Touchdown Zone -
The first 3,000 feet of the runway beginning at the threshold.
The area is used for determination of Touchdown Zone Elevation in the development
of straight-in landing minimums for instrument approaches. (See [ICAO]
Touchdown Zone)
[ICAO] Touchdown Zone -
The portion of a runway, beyond the threshold, where it is intended
landing aircraft first contact the runway.
Touchdown Zone Elevation (TDZE) -
The highest elevation in the first 3,000 feet of the landing
surface, TDZE is indicated on the instrument approach procedure chart when
straight-in landing minimums are authorized. (See Touchdown Zone)
Touchdown Zone Lighting - (See Airport Lighting)
Tower -
A terminal facility that uses air/ground communications, visual
signaling, and other devices to provide ATC services to aircraft operating
in the vicinity of an airport or on the movement area. Authorizes aircraft
to land or takeoff at the airport controlled by the tower or to transit
the Class D airspace area regardless of flight plan or weather conditions
(IFR or VFR). A tower may also provide approach control services (radar
or nonradar). (See Airport Traffic Control Service, Approach Control Facility,
Approach Control Service, Movement Area, Tower Enroute Control Service)
(Refer to AIM) (See [ICAO] Aerodrome Control Tower)
Tower Enroute Control Service (TECS) -
The control of IFR enroute traffic within delegated airspace
between two or more adjacent approach control facilities. This service
is designed to expedite traffic and reduce control and pilot communication
requirements.
Tower To Tower - (See Tower Enroute Control Service)
TPX-42 -
A numeric beacon decoder equipment/system. It is designed to
be added to terminal radar systems for beacon decoding. It provides rapid
target identification, reinforcement of the primary radar target, and altitude
information from Mode C. (See Automated Radar Terminal Systems, Transponder)
Track -
The actual flight path of an aircraft over the surface of the
earth. (See Course, Route, Flight Path) (See [ICAO] Track)
[ICAO] Track -
The projection on the earth's surface of the path of an aircraft,
the direction of which path at any point is usually expressed in degrees
from North (True, Magnetic, or Grid)
Traffic -
1. A term used by a controller to transfer radar identification
of an aircraft to another controller for the purpose of coordinating separation
action. Traffic is normally issued:
(a) in response to a handoff or point out,
(b) in anticipation of a handoff or point out, or
(c) in conjunction with a request for control of an aircraft.
2. A term used by ATC to refer to one or more aircraft.
Traffic Advisories -
Advisories issued to alert pilots to other known or observed
air traffic which may be in such proximity to the position or intended
route of flight of their aircraft to warrant their attention. Such advisories
may be based on:
a. Visual observation.
b. Observation of radar identified and nonidentified aircraft
targets on an ATC radar display, or
c. Verbal reports from pilots or other facilities.
Note 1: The word "traffic" followed by additional information,
if known, is used to provide such advisories; e.g., "Traffic, 2 o'clock,
one zero miles, southbound, eight thousand."
Note 2: Traffic advisory service will be provided to the extent
possible depending on higher priority duties of the controller or other
limitations; e.g., radar limitations, volume of traffic, frequency congestion,
or controller workload. Radar/nonradar traffic advisories do not relieve
the pilot of his responsibility to see and avoid other aircraft. Pilots
are cautioned that there are many times when the controller is not able
to give traffic advisories concerning all traffic in the aircraft's proximity;
in other words, when a pilot requests or is receiving traffic advisories,
he should not assume that all traffic will be issued. (Refer to AIM)
{New-98-3 Revised February 26, 1998}
TRAFFIC ALERT (aircraft call sign), TURN (left/right) IMMEDIATELY,
(climb/descend) AND MAINTAIN (altitude). (See Safety Alert)
Traffic Alert And Collision Avoidance System (TCAS) -
An airborne collision avoidance system based on radar beacon
signals which operates independent of ground based equipment. TCAS-I generates
traffic advisories only. TCAS-II generates traffic advisories, and resolution
(collision avoidance) advisories in the vertical plane.
Traffic Information - (See Traffic Advisories)
TRAFFIC IN SIGHT -
Used by pilots to inform a controller that previously issued
traffic is in sight. (See Negative Contact, Traffic Advisories)
Traffic Management Program Alert (TMPA) -
A term used in a Notice to Airmen (NOTAM) issued in conjunction
with a special traffic management program to alert pilots to the existence
of the program and to refer them to either the Notices to Airmen publication
or a special traffic management program advisory message for program details.
The contraction TMPA is used in NOTAM text.
Traffic Management Unit (TMU) -
The entity in ARTCCs and designated terminals responsible for
direct involvement in the active management of facility traffic. Usually
under the direct supervision of an assistant manager for traffic management.
TRAFFIC NO FACTOR -
Indicates that the traffic described in a previously issued traffic
advisory is no factor.
TRAFFIC NO LONGER OBSERVED -
Indicates that the traffic described in a previously issued traffic
advisory is no longer depicted on radar, but may still be a factor.
Traffic Pattern -
The traffic flow that is prescribed for aircraft landing at,
taxiing on, or taking off from an airport. The components of a typical
traffic pattern are upwind leg, crosswind leg, downwind leg, base leg,
and final approach.
1. Upwind Leg - A flight path parallel to the landing runway
in the direction of landing.
2. Crosswind Leg - A flight path at right angles to the landing
runway off its upwind end.
3. Downwind Leg - A flight path parallel to the landing runway
in the direction opposite to landing. The downwind leg normally extends
between the crosswind leg and the base leg.
4. Base Leg - A flight path at right angles to the landing runway
off its approach end. The base leg normally extends from the downwind leg
to the intersection of the extended runway centerline.
5. Final Approach - A flight path in the direction of landing
along the extended runway centerline. The final approach normally extends
from the base leg to the runway. An aircraft making a straight-in approach
VFR is also considered to be on final approach. (See Straight-In Approach
- VFR, Taxi Patterns) (Refer to AIM, FAR Part 91) (See [ICAO] Aerodrome
Traffic Circuit)
Transcribed Weather Broadcast (TWEB) -
A continuous recording of meteorological and aeronautical information
that is broadcast on L/MF and VOR facilities for pilots. (Refer to AIM)
Transfer of Control -
That action whereby the responsibility for the separation of
an aircraft is transferred from one controller to another. (See [ICAO]
Transfer of Control)
[ICAO] Transfer of Control -
Transfer of responsibility for providing air traffic control
service.
Transferring Controller -
A controller/facility transferring control of an aircraft to
another controller/facility. (See [ICAO] Transferring Unit/Controller)
Transferring Facility - (See Transferring Controller)
[ICAO] Transferring Unit/Controller -
Air traffic control unit/air traffic controller in the process
of transferring the responsibility for providing air traffic control service
to an aircraft to the next air traffic control unit/air traffic controller
along the route of flight.
Note: See definition of accepting unit/controller.
{New-98-8 Revised August 13, 1998. "DP" was "SID"}
Transition -
a. The general term that describes the change from one phase
of flight or flight condition to another; e.g., transition from enroute
flight to the approach or transition from instrument flight to visual flight.
b. A published procedure (DP Transition) used to connect the
basic DP to one of several enroute airways/jet routes, or published procedure
(STAR Transition) used to connect one of several enroute airways/jet routes
to the basic STAR. (Refer to DP/STAR Charts)
Transitional Airspace -
That portion of controlled airspace wherein aircraft change from
one phase of flight or flight condition to another.
Transition Point -
A point at an adapted number of miles from the vertex at which
an arrival aircraft would normally commence descent from its enroute altitude.
This is the first fix adapted on the arrival speed segments.
Transmissometer -
An apparatus used to determine visibility by measuring the transmission
of light through the atmosphere. It is the measurement source of determining
runway visual range (RVR) and runway visibility valve (RVV). (See Visibility)
TRANSMITTING IN THE BLIND -
A transmission from one station to other stations in circumstances
where two-way communication cannot be established, but where it is believed
that the called stations may be able to receive the transmission.
Transponder -
The airborne radar beacon receiver/transmitter portion of the
Air Traffic Control Radar Beacon System (ATCRBS) which automatically receives
radio signals from interrogators on the ground, and selectively replies
with a specific reply pulse or pulse group only to those interrogations
being received on the mode to which it is set to respond. (See Interrogator)
(Refer to AIM) (See [ICAO] Transponder)
[ICAO] Transponder -
A receiver/transmitter which will generate a reply signal upon
proper interrogation; the interrogation and reply being on different frequencies.
Transponder Codes - (See Codes)
TRSA - (See Terminal Radar Service Area)
Turbojet Aircraft -
An aircraft having a jet engine in which the energy of the jet
operates a turbine which in turn operates the air compressor.
Turboprop Aircraft -
An aircraft having a jet engine in which the energy of the jet
operates a turbine which drives the propeller.
Turn Anticipation -
(maneuver anticipation).
TWEB - (See Transcribed Weather Broadcast)
TVOR - (See Terminal - Very High Frequency Omnidirectional Range Station)
Two-Way Radio Communications Failure - (See Lost Communications)
U
UDF - (See Direction Finder)
UHF - (See Ultrahigh Frequency)
Ultrahigh Frequency (UHF) -
The frequency band between 300 and 3,000 MHz. The bank of radio
frequencies used for military air/ground voice communications. In some
instances this may go as low as 225 MHz and still be referred to as UHF.
Ultralight Vehicle -
An aeronautical vehicle operated for sport or recreational purposes
which does not require FAA registration, an airworthiness certificate,
nor pilot certification. They are primarily single occupant vehicles, although
some two place vehicles are authorized for training purposes. Operation
of an ultralight vehicle in certain airspace requires authorization from
ATC. (See FAR Part 103)
UNABLE -
Indicates inability to comply with a specific instruction, request,
or clearance.
Under The Hood -
Indicates that the pilot is using a hood to restrict visibility
outside the cockpit while simulating instrument flight. An appropriately
rated pilot is required in the other control seat while this operation
is being conducted. (Refer to FAR Part 91)
UNICOM -
A nongovernment communication facility which may provide airport
information at certain airports. Locations and frequencies of UNICOMs are
shown on aeronautical charts and publications. (Refer to AIM, Airport/Facility
Directory)
Unpublished Route -
A route for which no minimum altitude is published or charted
for pilot use. It may include a direct route between NAVAIDs, a radial,
a radar vector, or a final approach course beyond the segments of an instrument
approach procedure. (See Published Route, Route)
Upwind Leg - (See Traffic Pattern)
Urgency -
A condition of being concerned about safety and of requiring
timely but not immediate assistance; a potential distress condition. (See
[ICAO] Urgency)
[ICAO] Urgency -
A condition concerning the safety of an aircraft or other vehicle,
or of person on board or in sight, but which does not require immediate
assistance.
USAFIB - (See Army Aviation Flight Information Bulletin)
UVDF - (See Direction Finder)
V
VASI - (See Visual Approach Slope Indicator)
VDF - (See Direction Finder)
VDP - (See Visual Descent Point)
Vector -
A heading issued to an aircraft to provide navigational guidance
by radar. (See [ICAO] Radar Vectoring)
VERIFY -
Request confirmation of information; e.g., "verify assigned altitude."
VERIFY SPECIFIC DIRECTION OF TAKEOFF (OR TURNS AFTER TAKEOFF) -
Used by ATC to ascertain an aircraft's direction of takeoff and/or
direction of turn after takeoff. It is normally used for IFR departures
from an airport not having a control tower. When direct communication with
the pilot is not possible, the request and information may be relayed through
an FSS, dispatcher, or by other means. (See IFR Takeoff Minimums and Departure
Procedures)
Vertex -
The last fix adapted on the arrival speed segments. Normally,
it will be the outer marker of the runway in use. However, it may be the
actual threshold or other suitable common point on the approach path for
the particular runway configuration.
Vertex Time of Arrival (VTA) -
A calculated time of aircraft arrival over the adapted vertex
for the runway configuration in use. The time is calculated via the optimum
flight path using adapted speed segments.
Vertical Separation -
Separation established by assignment of different altitudes or
flight levels. (See Separation) (See [ICAO] Vertical Separation)
[ICAO] Vertical Separation -
Separation between aircraft expressed in units of vertical distance.
Vertical Takeoff And Landing Aircraft (VTOL) -
Aircraft capable of vertical climbs and/or descents and of using
very short runways or small areas for takeoff and landings. These aircraft
include, but are not limited to, helicopters. (See Short Takeoff and Landing
Aircraft)
Very High Frequency (VHF) -
The frequency band between 30 and 300 MHz. Portions of this band,
108 to 118 MHz, are used for certain NAVAIDs; 118 to 136 MHz are used for
civil air/ground voice communications. Other frequencies in this band are
used for purposes not related to air traffic control.
Very High Frequency Omnidirectional Range Station - (See VOR)
Very Low Frequency (VLF) -
The frequency band between 3 and 30 kHz.
VFR - (See Visual Flight Rules)
VFR Aircraft -
An aircraft conducting flight in accordance with visual flight
rules. (See Visual Flight Rules)
VFR CONDITIONS -
Weather conditions equal to or better than the minimum for flight
under visual flight rules. The term may be used as an ATC clearance/instruction
only when:
1. An IFR aircraft requests a climb/descent in VFR conditions.
2. The clearance will result in noise abatement benefits where
part of the IFR departure route does not conform to an FAA approved noise
abatement route or altitude.
3. A pilot has requested a practice instrument approach and
is not on an IFR flight plan.
All pilots receiving this authorization must comply with the
VFR visibility and distance from cloud criteria in FAR Part 91. Use of
the term does not relieve controllers of their responsibility to separate
aircraft in Class B and Class C airspace or TRSAs as required by FAA Order
7110.65. When used as an ATC clearance/instruction the term may be abbreviated
"VFR;" e.g., "MAINTAIN VFR," "CLIMB/DESCEND VFR," etc.
VFR Flight - (See VFR Aircraft)
VFR Military Training Routes -
Routes used by the Department of Defense and associated Reserve
and Air Guard units for the purpose of conducting low altitude navigation
and tactical training under VFR below 10,000 feet MSL at airspeeds in excess
of 250 knots IAS.
VFR NOT RECOMMENDED -
An advisory provided by a flight service station to a pilot during
a preflight or in-flight weather briefing that flight under visual flight
rules is not recommended. To be given when the current and/or forecast
weather conditions are at or below VFR minimums. It does not abrogate the
pilot's authority to make his own decision.
VFR-ON-TOP -
ATC authorization for an IFR aircraft to operate in VFR conditions
at any appropriate VFR altitude (as specified in FAR and as restricted
by ATC). A pilot receiving this authorization must comply with the VFR
visibility, distance from cloud criteria, and the minimum IFR altitudes
specified in FAR Part 91. The use of this term does not relieve controllers
of their responsibility to separate aircraft in Class B and Class C airspace
or TRSAs as required by FAA Order 7110.65.
VFR Terminal Area Charts -
(See Aeronautical Chart)
VHF - (See Very High Frequency)
VHF Omnidirectional Range/Tactical Air Navigation - (See VORTAC)
Video Map -
An electronically displayed map on the radar display that may
depict data such as airports, heliports, runway centerline extensions,
hospital emergency landing areas, NAVAIDs and fixes, reporting points,
airway/route centerlines, boundaries, handoff points, special use tracks,
obstructions, prominent geographic features, map alignment indicators,
range accuracy marks, minimum vectoring altitudes.
Visibility -
The ability, as determined by atmospheric conditions and expressed
in units of distance, to see and identify prominent unlighted objects by
day and prominent lighted objects by night. Visibility is reported as statute
miles, hundreds of feet or meters. (Refer to FAR Part 91, AIM)
1. Flight Visibility - The average forward horizontal distance
from the cockpit of an aircraft in flight, at which prominent unlighted
objects may be seen and identified by day and prominent lighted objects
may be seen and identified by night.
2. Ground Visibility - Prevailing horizontal visibility near
the earth's surface as reported by the United States National Weather Service
or an accredited observer.
3. Prevailing Visibility - The greatest horizontal visibility
equaled or exceeded throughout at least half the horizon circle which need
not necessarily be continuous.
4. Runway Visibility Value (RVV) - The visibility determined
for a particular runway by a transmissometer. A meter provides a continuous
indication of the visibility (reported in miles or fractions of miles)
for the runway. RVV is used in lieu of prevailing visibility in determining
minimums for a particular runway.
5. Runway Visual Range (RVR) - An instrumentally derived value,
based on standard calibrations, that represents the horizontal distance
a pilot will see down the runway from the approach end. It is based on
the sighting of either high intensity runway lights or on the visual contrast
of other targets whichever yields the greater visual range. RVR, in contrast
to prevailing or runway visibility, is based on what a pilot in a moving
aircraft should see looking down the runway. RVR is horizontal visual range,
not slant visual range. It is based on the measurement of a transmissometer
made near the touchdown point of the instrument runway and is reported
in hundreds of feet. RVR is used in lieu of RVV and/or prevailing visibility
in determining minimums for a particular runway.
a. Touchdown RVR - The RVR visibility readout values obtained
from RVR equipment serving the runway touchdown zone.
b. Mid-RVR - The RVR readout values obtained from RVR
equipment located midfield of the runway.
c. Rollout RVR - The RVR readout values obtained from
RVR equipment located nearest the rollout end of the runway.
(See [ICAO] Visibility, [ICAO] Flight Visibility, [ICAO] Ground
Visibility, [ICAO] Runway Visual Range)
[ICAO] Visibility -
The ability, as determined by atmospheric conditions and expressed
in units of distance, to see and identify prominent unlighted objects by
day and prominent lighted objects by night.
[ICAO] Flight Visibility - The visibility forward from the cockpit
of an aircraft in flight.
[ICAO] Ground Visibility - The visibility at an aerodrome as
reported by an accredited observer.
[ICAO] Runway Visual Range (RVR) - The range over which the pilot
of an aircraft on the centerline of a runway can see the runway surface
markings or the lights delineating the runway or identifying its centerline.
Visual Approach -
An approach conducted on an instrument flight rules (IFR) flight
plan which authorizes the pilot to proceed visually and clear of clouds
to the airport. The pilot must, at all times, have either the airport or
the preceding aircraft in sight. This approach must be authorized and under
the control of the appropriate air traffic control facility. Reported weather
at the airport must be ceiling at or above 1,000 feet and visibility of
3 miles or greater.
(See [ICAO] Visual Approach)
[ICAO] Visual Approach -
An approach by an IFR flight when either part or all of an instrument
approach procedure is not completed and the approach is executed in visual
reference to terrain.
Visual Approach Slope Indicator (VASI) - (See Airport Lighting)
Visual Descent Point (VDP) -
A defined point on the final approach course of a nonprecision
straight-in approach procedure from which normal descent from the MDA to
the runway touchdown point may be commenced, provided the approach threshold
of that runway, or approach lights, or other markings identifiable with
the approach end of that runway are clearly visible to the pilot.
Visual Flight Rules (VFR) -
Rules that govern the procedures for conducting flight under
visual conditions. The term "VFR" is also used in the United States to
indicate weather conditions that are equal to or greater than minimum VFR
requirements. In addition, it is used by pilots and controllers to indicate
type of flight plan. (See Instrument Flight Rules, Instrument Meteorological
Conditions, Visual Meteorological Conditions) (Refer to FAR Part 91 and
AIM)
Visual Holding -
The holding of aircraft at selected, prominent geographical fixes
which can be easily recognized from the air. (See Holding Fix)
Visual Meteorological Conditions (VMC) -
Meteorological conditions expressed in terms of visibility, distance
from cloud, and ceiling equal to or better than specified minima. (See
Instrument Flight Rules, Instrument Meteorological Conditions, Visual Flight
Rules)
Visual Separation -
A means employed by ATC to separate aircraft in terminal areas
and en route airspace in the NAS. There are two ways to effect this separation:
a. The tower controller sees the aircraft involved and issues
instructions, as necessary, to ensure that the aircraft avoid each other.
b. A pilot sees the other aircraft involved and upon instructions
from the controller provides his own separation by maneuvering his aircraft
as necessary to avoid it. This may involve following another aircraft or
keeping it in sight until it is no longer a factor. (See: See and Avoid)
(Refer to FAR Part 91)
VLF - (See Very Low Frequency)
VMC - (See Visual Meteorological Conditions)
Voice Switching and Control System (VSCS) -
The VSCS is a computer controlled switching system that provides
air traffic controllers with all voice circuits (air to ground and ground
to ground) necessary for air traffic control.
VOR -
A ground based electronic navigation aid transmitting very high
frequency navigation signals, 360 degrees in azimuth, oriented from magnetic
north. Used as the basis for navigation in the National Airspace System.
The VOR periodically identifies itself by Morse Code and may have an additional
voice identification feature. Voice features may be used by ATC or FSS
for transmitting instructions/information to pilots. (See Navigational
Aid) (Refer to AIM)
VORTAC -
A navigation aid providing VOR azimuth, TACAN azimuth, and TACAN
distance measuring equipment (DME) at one site. (See Distance Measuring
Equipment, Navigational Aid, TACAN, VOR) (Refer to AIM)
Vortices -
Circular patterns of air created by the movement of an airfoil
through the air when generating lift. As an airfoil moves through the atmosphere
in sustained flight, an area of low pressure is created above it. The air
flowing from the high pressure area to the low pressure area around and
about the tips of the airfoil tends to roll up into two rapidly rotating
vortices, cylindrical in shape. These vortices are the most predominant
parts of aircraft wake turbulence and their rotational force is dependent
upon the wing loading, gross weight, and speed of the generating aircraft.
The vortices from medium to heavy aircraft can be of extremely high velocity
and hazardous to smaller aircraft. (See Aircraft Classes, Wake Turbulence)
(Refer to AIM)
VOR Test Signal - (See VOT)
VOT -
A ground facility which emits a test signal to check VOR receiver
accuracy. Some VOTs are available to the user while airborne, and others
are limited to ground use only. (Refer to FAR Part 91, AIM, Airport/Facility
Directory)
VR - (See VFR Military Training Route)
VSCS - (See Voice Switching and Control System)
VTA - (See Vertex Time of Arrival)
VTOL Aircraft - (See Vertical Takeoff and Landing Aircraft)
W
WA - (See AIRMET, Weather Advisory)
Wake Turbulence -
Phenomena resulting from the passage of an aircraft through the
atmosphere. The term includes vortices, thrust stream turbulence, jet blast,
jet wash, propeller wash, and rotor wash both on the ground and in the
air. (See Aircraft Classes, Jet Blast, Vortices) (Refer to AIM)
Warning Area - (See Special Use Airspace)
Waypoint -
A predetermined geographical position used for route/instrument
approach definition, or progress reporting purposes, that is defined relative
to a VORTAC station or in terms of latitude/longitude coordinates.
Weather Advisory (WS) (WST) (WA) (CWA) -
In aviation weather forecast practice, an expression of hazardous
weather conditions not predicted in the area forecast, as they affect the
operation of air traffic and as prepared by the NWS. (See SIGMET, AIRMET)
WHEN ABLE -
When used in conjunction with ATC instructions, gives the pilot
the latitude to delay compliance until a condition or even has been reconciled.
Unlike "pilot discretion," when instructions are prefaced "when able,"
the pilot is expected to seek the first opportunity to comply. Once a maneuver
has been initiated, the pilot is expected to continue until the specifications
of the instructions have been met. "When able," should not be used when
expeditious compliance is required.
WILCO -
I have received your message, understand it, and will comply
with it.
Wind Shear - (See Windshear)
Windshear -
A change in wind speed and/or wind direction in a short distance
resulting in a tearing or shearing effect. It can exist in a horizontal
or vertical direction and occasionally in both.
Wing Tip Vortices - (See Vortices)
WORDS TWICE -
1. As a request: "Communication is difficult. Please say every
phrase twice."
2. As information: "Since communications are difficult, every
phrase in this message will be spoken twice."
World Aeronautical Charts -
(See Aeronautical Chart)
WS - (See SIGMET, Weather Advisory)
WST - (See Convective SIGMET, Weather Advisory)
X
Y
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