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AAI -- AZIMUTH (MLS)
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, location, 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.
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.
ACC [ICAO]- (See AREA CONTROL CENTER.)
ACCELERATE-STOP DISTANCE AVAILABLE- The runway plus stopway length declared
available and suitable for the acceleration and deceleration of an airplane
aborting a takeoff.
ACCELERATE-STOP DISTANCE AVAILABLE [ICAO]- The length of the take-off
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 term ACKNOWLEDGE.)
ACKNOWLEDGE [ICAO]- Let me know that you have received and understood this
message.
ACLS- (See AUTOMATIC CARRIER LANDING SYSTEM.)
ACLT- (See ACTUAL CALCULATED LANDING TIME.)
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.
(See ICAO term ACROBATIC FLIGHT.)
ACROBATIC FLIGHT [ICAO]- 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 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:
b. Vectors, when requested by the pilot, to assist aircraft
receiving traffic advisories to avoid observed traffic.
c. Altitude deviation information of 300 feet or more from an
assigned altitude as observed on a verified (reading correctly) automatic
altitude readout (Mode C.)
d. Advisories that traffic is no longer a factor.
e. Weather and chaff information.
g. Bird activity information.
h. 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 congestion, and
controller workload. The controller has complete discretion for determining
if he/she 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/her.
(See TRAFFIC ADVISORIES.)
ADF- (See AUTOMATIC DIRECTION FINDER.)
ADIZ- (See AIR DEFENSE IDENTIFICATION ZONE.)
ADLY- (See ARRIVAL DELAY.)
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.
ADVISORY FREQUENCY- The appropriate frequency to be used for Airport Advisory
Service.
(See LOCAL AIRPORT ADVISORY.)
(Refer to ADVISORY CIRCULAR NO. 90-42.)
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.)
(See TRAFFIC ADVISORIES.)
(See ADDITIONAL SERVICES.)
(See EN ROUTE FLIGHT ADVISORY
SERVICE.)
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.
AERODROME BEACON [ICAO]- Aeronautical beacon used to indicate the location
of an aerodrome from the air.
AERODROME CONTROL SERVICE [ICAO]- Air traffic control service for aerodrome
traffic.
AERODROME CONTROL TOWER [ICAO]- A unit established to provide air traffic
control service to aerodrome traffic.
AERODROME ELEVATION [ICAO]- The elevation of the highest point of the
landing area.
AERODROME TRAFFIC CIRCUIT [ICAO]- 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.)
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 Aeronautical 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. En Route Low Altitude Charts- Provide aeronautical information
for en route 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
en route 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. En Route High Altitude Charts- Provide aeronautical information
for en route 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.
g. Instrument Departure Procedure (DP) Charts-
Designed to expedite clearance delivery and to facilitate transition
between takeoff and en route 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
en route 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 term AERONAUTICAL CHART.)
AERONAUTICAL CHART [ICAO]- 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.
AERONAUTICAL INFORMATION PUBLICATION [AIP] [ICAO]- 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.
AIM- (See AERONAUTICAL INFORMATION MANUAL.)
AIP [ICAO]- (See AERONAUTICAL INFORMATION PUBLICATION.)
AIRBORNE DELAY- Amount of delay to be encountered in airborne holding.
AIR CARRIER DISTRICT OFFICE- 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 term AIRCRAFT.)
AIRCRAFT [ICAO]- 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.
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.
AIRCRAFT SITUATION DISPLAY- ASD is a computer system that receives radar
track data from all 20 CONUS ARTCC's, 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 en route sector
boundaries, fixes, airways, military and other special use airspace, airports,
and geopolitical boundaries. By using the ASD, a coordinator can monitor
any number of traffic situations or the entire systemwide traffic flows.
AIRCRAFT SURGE LAUNCH AND RECOVERY- Procedures used at USAF bases to
provide increased launch and recovery rates in 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.
AIR DEFENSE IDENTIFICATION ZONE- 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.
a. Domestic Air Defense Identification Zone. An ADIZ within
the United States along an international boundary of the United States.
b. Coastal Air Defense Identification Zone. An ADIZ over the
coastal waters of the United States.
c. 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.
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.
AIRMET's concern weather of less severity than that covered by SIGMET's
or Convective SIGMET's. AIRMET's 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.
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 take-off of aircraft.
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- 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.)
AIRPORT ELEVATION- The highest point of an airport's usable runways measured
in feet from mean sea level.
(See TOUCHDOWN ZONE ELEVATION.)
(See ICAO term AERODROME ELEVATION.)
AIRPORT/FACILITY DIRECTORY- 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.
AIRPORT LIGHTING- Various lighting aids that may be installed on an airport.
Types of airport lighting include:
a. 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. Condenser-Discharge
Sequential Flashing Lights/Sequenced Flashing Lights may be installed in
conjunction with the ALS at some airports. Types of Approach Light Systems
are:
1. ALSF-1- Approach Light System with Sequenced Flashing Lights
in ILS Cat-I configuration.
2. 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.
3. SSALF- Simplified Short Approach Light System with Sequenced
Flashing Lights.
4. SSALR- Simplified Short Approach Light System with Runway
Alignment Indicator Lights.
5. MALSF- Medium Intensity Approach Light System with Sequenced
Flashing Lights.
6. MALSR- Medium Intensity Approach Light System with Runway
Alignment Indicator Lights.
7. 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.
8. RAIL- Runway Alignment Indicator Lights-
Sequenced Flashing Lights which are installed only in combination with
other light systems.
9. ODALS- Omnidirectional Approach Lighting System consists
of seven omnidirectional flashing lights located in the 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 FAA Order 6850.2, VISUAL GUIDANCE LIGHTING SYSTEMS.)
b. 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.
c. 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.
d. 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.
e. Threshold Lights- Fixed green lights arranged symmetrically
left and right of the runway centerline, identifying the runway threshold.
f. 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.
g. 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
red 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 VASI's
which provide two visual glide paths to the same runway.
h. Boundary Lights- Lights defining the perimeter of an airport
or landing area.
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:
b. Nonprecision instrument.
AIRPORT REFERENCE POINT (ARP) - The approximate geometric center of all
usable runway surfaces.
AIRPORT RESERVATION OFFICE- 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 dualpeaked (two
quick) white flashes between the green flashes.
(See SPECIAL VFR OPERATIONS.)
(See INSTRUMENT FLIGHT RULES.)
(See ICAO term AERODROME BEACON.)
AIRPORT SURFACE DETECTION EQUIPMENT- 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- 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 ICAO term AERODROME CONTROL SERVICE.)
AIRPORT TRAFFIC CONTROL TOWER- (See TOWER.)
AIR ROUTE SURVEILLANCE RADAR- Air route traffic control center (ARTCC)
radar used primarily to detect and display an aircraft's position while
en route 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- A facility established to provide
air traffic control service to aircraft operating on IFR flight plans within
controlled airspace and principally during the en route phase of flight.
When equipment capabilities and controller workload permit, certain advisory/assistance
services may be provided to VFR aircraft.
(See EN ROUTE AIR TRAFFIC CONTROL SERVICES.)
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:
a. Indicated Airspeed- The speed shown on the aircraft airspeed
indicator. This is the speed used in pilot/controller communications under
the general term "airspeed."
b. True Airspeed- The airspeed of an aircraft relative to undisturbed
air. Used primarily in flight planning and en route 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.
AIR TRAFFIC- Aircraft operating in the air or on an airport surface, exclusive
of loading ramps and parking areas.
(See ICAO term AIR TRAFFIC.)
AIR TRAFFIC [ICAO]- All aircraft in flight or operating on the manoeuvring
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. FAR 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 ICAO term AIR TRAFFIC CONTROL CLEARANCE.)
AIR TRAFFIC CONTROL- A service operated by appropriate authority to promote
the safe, orderly and expeditious flow of air traffic.
(See ICAO term AIR TRAFFIC CONTROL SERVICE.)
AIR TRAFFIC CONTROL CLEARANCE [ICAO]- 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, en route, 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.)
AIR TRAFFIC CONTROL SERVICE [ICAO]- A service provided for the purpose
of:
a. Preventing collisions:
2. On the manoeuvring area between aircraft and obstructions;
and
b. 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.)
(See FLIGHT SERVICE STATION.)
(See ICAO term CONTROLLER.)
AIR TRAFFIC CONTROL SYSTEM COMMAND CENTER- An Air Traffic Operations Service
facility consisting of four operational units.
a. 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.)
b. Central Altitude Reservation Function (CARF). Responsible
for coordinating, planning, and approving special user requirements under
the Altitude Reservation (ALTRV) concept.
(See ALTITUDE RESERVATION.)
c. 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.)
d. 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:
a. Flight Information Service:
c. Air Traffic Advisory Service:
d. Air Traffic Control Service:
2. Approach Control Service, or
3. 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.
AIRWAY [ICAO]- 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.
AIT- (See AUTOMATED INFORMATION TRANSFER.)
ALERFA (Alert Phase) [ICAO]- A situation wherein apprehension exists
as to the safety of an aircraft and its occupants.
ALERT AREA- (See SPECIAL USE AIRSPACE.)
ALERT NOTICE- 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.
ALNOT- (See ALERT NOTICE.)
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.
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.)
ALTERNATE AERODROME [ICAO]- An aerodrome to which an aircraft may proceed
when it becomes either impossible or inadvisable to proceed to or to land
at the aerodrome of intended landing.
Note: The aerodrome from which a flight departs may also be an en-route
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 ICAO term 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.)
ALTITUDE- The height of a level, point, or object measured in feet Above
Ground Level (AGL) or from Mean Sea Level (MSL.)
a. MSL Altitude- Altitude expressed in feet measured from mean
sea level.
b. AGL Altitude- Altitude expressed in feet measured above ground
level.
c. 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 term ALTITUDE.)
ALTITUDE [ICAO]- 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.)
(See ALPHANUMERIC DISPLAY.)
ALTITUDE RESERVATION- Airspace utilization under prescribed conditions
normally employed for the mass movement of aircraft or other special user
requirements which cannot otherwise be accomplished. ALTRV's 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.)
(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.)
(See 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,
en route aircraft. At some airports not served by an approach control facility,
the ARTCC provides limited approach control service.
(See ICAO term APPROACH CONTROL SERVICE.)
APPROACH CONTROL SERVICE [ICAO]- 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 ICAO term APPROACH SEQUENCE.)
APPROACH SEQUENCE [ICAO]- 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.
APPROPRIATE ATS AUTHORITY [ICAO]- 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-
a. Regarding flight over the high seas: the relevant authority
is the State of Registry.
b. 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 En Route 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 En Route 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.
APRON [ICAO]- 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).
AREA CONTROL CENTER [ICAO]- An ICAO term for an air traffic control
facility primarily responsible for ATC services being provided IFR aircraft
during the en route 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 en route and approach
altitudes. The usable 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 term 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- 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.
ARRIVAL AIRCRAFT INTERVAL- 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- 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/MDM of the sector which controls the meter fix.
ARRIVAL SEQUENCING PROGRAM- 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 SYSTEMS.)
ASD- (See AIRCRAFT SITUATION DISPLAY.)
ASDA- (See ACCELERATE-STOP DISTANCE AVAILABLE.)
ASDA [ICAO]- (See ICAO Term 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.
ATC ASSIGNED AIRSPACE- 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."
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.)
ATIS [ICAO]- (See ICAO Term AUTOMATIC TERMINAL INFORMATION SERVICE.)
ATS Route [ICAO]- A specified route designed for channelling the flow
of traffic as necessary for the provision of air traffic services.
Note: The term "ATS Route" is used to mean variously, 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 onboard 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- 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- 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 co-exists with the alphanumeric display.
In addition to enhancing visualization of the air traffic situation, ARTS
facilitate intra/inter-facility 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.
a. 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 ARTCC's and other ARTS II, IIA, III, and IIIA facilities.
b. 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 ARTCC's and other ARTS II, IIA, III, and IIIA facilities.
c. ARTS III. The Beacon Tracking Level 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 ARTCC's and other ARTS III facilities.
d. 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- 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- 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 NONDIRECTIONAL BEACON.)
AUTOMATIC TERMINAL INFORMATION SERVICE- 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 niner six. I-L-S Runway Two Five Left
approach in use, Runway Two Five Right closed, advise you have Alfa."
(See ICAO term AUTOMATIC TERMINAL INFORMATION SERVICE.)
AUTOMATIC TERMINAL INFORMATION SERVICE [ICAO]- 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.
a. Autorotative Landing/Touchdown Autorotation. Used by a pilot
to indicate that the landing will be made without applying power to the
rotor.
b. 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.
c. 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.
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 EN ROUTE FLIGHT ADVISORY SERVICE.)
(See TRANSCRIBED WEATHER BROADCAST.)
(See PILOTS AUTOMATIC TELEPHONE WEATHER ANSWERING SERVICE.)
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.