PCG TACAN -- TWO-WAY RADIO COMMUNICATIONS FAILURE
TACAN -- TWO-WAY RADIO COMMUNICATIONS FAILURE
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.
(See TACTICAL AIR NAVIGATION.)
TACTICAL AIR NAVIGATION- 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.
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.
TAKE-OFF DISTANCE AVAILABLE [ICAO]- The length of the take-off run available
plus the length of the clearway, if provided.
TAKE-OFF RUN AVAILABLE [ICAO]- The length of runway declared available
and suitable for the ground run of an aeroplane take-off.
TARGET- The indication shown on a radar display resulting from a primary
radar return or a radar beacon reply.
TARGET [ICAO]- In radar:
a. Generally, any discrete object which reflects or retransmits
energy back to the radar equipment.
b. Specifically, an object of radar search or surveillance.
TARGET RESOLUTION- A process to ensure that correlated radar targets do
not touch. Target resolution shall be applied as follows:
a. Between the edges of two primary targets or the edges of
the ASR-9 primary target symbol.
b. Between the end of the beacon control slash and the edge
of a primary target.
c. 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 Part 135.100 [Note]). Also, it describes the surface
movement of helicopters equipped with wheels.
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.
(Refer to FAR Part 135.100.)
TAXI PATTERNS- Patterns established to illustrate the desired flow of ground
traffic for the different runways or airport areas available for use.
(See CLEARED FOR TAKEOFF.)
(See TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM.)
(See THRESHOLD CROSSING HEIGHT.)
(See TENTATIVE CALCULATED LANDING TIME.)
TELEPHONE INFORMATION BRIEFING SERVICE- A continuous telephone recording
of meteorological and/or aeronautical information.
TENTATIVE CALCULATED LANDING TIME- 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.
(See TOUCHDOWN ZONE ELEVATION.)
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 en route
TERMINAL RADAR SERVICE AREA- Airspace surrounding designated airports wherein
ATC provides radar vectoring, sequencing, and separation on a full-time
basis for all IFR and participating VFR aircraft. The AIM contains an explanation
of TRSA. TRSA's are depicted on VFR aeronautical charts. Pilot participation
is urged but is not mandatory.
(See APPROACH CONTROL FACILITY.)
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 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
a. 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.
b. 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
c. 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.
d. 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.)
(See TERMINAL RADAR SERVICE AREA.)
(Refer to AIRPORT/FACILITY DIRECTORY.)
(See TERMINAL RADAR PROGRAM.)
TERMINAL-VERY HIGH FREQUENCY OMNIDIRECTIONAL RANGE STATION- A very high
frequency terminal omnirange station located on or near an airport and
used as an approach aid.
TERRAIN FOLLOWING- 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
(Refer to AIRPORT/FACILITY DIRECTORY.)
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
THAT IS CORRECT- The understanding you have is right.
THRESHOLD- The beginning of that portion of the runway usable for landing.
THRESHOLD CROSSING HEIGHT- 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 DISPLACED THRESHOLD.)
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.
(See TELEPHONE INFORMATION BRIEFING SERVICE.)
(See TRAFFIC MANAGEMENT PROGRAM ALERT.)
(See TRAFFIC MANAGEMENT UNIT.)
(See ICAO Term TAKE-OFF DISTANCE 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.
(See ICAO Term TAKE-OFF RUN AVAILABLE.)
TOTAL ESTIMATED ELAPSED TIME [ICAO]- For IFR flights, the estimated
time required from take-off to arrive over that 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.
TOUCH-AND-GO- An operation by an aircraft that lands and departs on a runway
without stopping or exiting the runway.
(See ESTIMATED ELAPSED TIME.)
a. The point at which an aircraft first makes contact with the
b. Concerning a precision radar approach (PAR), it is the point
where the glide path intercepts the landing surface.
TOUCHDOWN [ICAO]- The point where the nominal glide path intercepts the
(See ICAO term TOUCHDOWN.)
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 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.
TOUCHDOWN ZONE [ICAO]- The portion of a runway, beyond the threshold, where
it is intended landing aircraft first contact the runway.
(See ICAO term TOUCHDOWN ZONE.)
TOUCHDOWN ZONE ELEVATION- 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.
TOUCHDOWN ZONE 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
(See AIRPORT TRAFFIC CONTROL SERVICE.)
(See APPROACH CONTROL FACILITY.)
(See APPROACH CONTROL SERVICE.)
(See TOWER EN ROUTE CONTROL SERVICE.)
TOWER EN ROUTE CONTROL SERVICE- The control of IFR en route traffic within
delegated airspace between two or more adjacent approach control facilities.
This service is designed to expedite traffic and reduce control and pilot
(See ICAO term AERODROME CONTROL TOWER.)
TOWER TO TOWER-
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 TOWER EN ROUTE CONTROL SERVICE.)
TRACK- The actual flight path of an aircraft over the surface of the earth.
TRACK [ICAO]- 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).
(See AUTOMATED RADAR TERMINAL SYSTEMS.)
a. 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:
1. in response to a handoff or point out,
2. in anticipation of a handoff or point out, or
3. in conjunction with a request for control of an aircraft.
b. 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:
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.
TRAFFIC ALERT (aircraft call sign), TURN (left/right) IMMEDIATELY,
(climb/descend) AND MAINTAIN (altitude). (See SAFETY ALERT.)
TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM- 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 IN SIGHT- Used by pilots to inform a controller that
previously issued traffic is in sight.
(See TRAFFIC ADVISORIES.)
TRAFFIC MANAGEMENT PROGRAM ALERT- 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.
(See TRAFFIC ADVISORIES.)
TRAFFIC MANAGEMENT UNIT- The entity in ARTCC's 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 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.
a. Upwind Leg- A flight path parallel to the landing runway
in the direction of landing.
b. Crosswind Leg- A flight path at right angles to the landing
runway off its upwind end.
c. 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.
d. 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.
e. 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.)
TRANSCRIBED WEATHER BROADCAST- A continuous recording of meteorological
and aeronautical information that is broadcast on L/MF and VOR facilities
TRANSFER OF CONTROL- That action whereby the responsibility for the separation
of an aircraft is transferred from one controller to another.
(See ICAO term AERODROME TRAFFIC CIRCUIT.)
TRANSFER OF CONTROL [ICAO]- Transfer of responsibility for providing air
traffic control service.
(See ICAO term TRANSFER OF CONTROL.)
TRANSFERRING CONTROLLER- A controller/facility transferring control
of an aircraft to another controller/facility.
(See ICAO term TRANSFERRING UNIT/CONTROLLER.)
TRANSFERRING UNIT/CONTROLLER [ICAO]- 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.
(See TRANSFERRING CONTROLLER.)
Note: See definition of accepting unit/controller.
a. The general term that describes the change from one phase
of flight or flight condition to another; e.g., transition from en route
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 en route airways/jet routes, or a published
procedure (STAR Transition) used to connect one of several en route airways/jet
routes to the basic STAR.
TRANSITIONAL AIRSPACE- That portion of controlled airspace wherein aircraft
change from one phase of flight or flight condition to another.
(Refer to DP/STAR Charts.)
TRANSITION POINT- A point at an adapted number of miles from the vertex
at which an arrival aircraft would normally commence descent from its en
route 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 for determining runway visual range (RVR) and runway 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.
TRANSPONDER [ICAO]- A receiver/transmitter which will generate a reply
signal upon proper interrogation; the interrogation and reply being on
(See ICAO term TRANSPONDER.)
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.
(See TERMINAL RADAR SERVICE AREA.)
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).
(See TERMINAL-VERY HIGH FREQUENCY OMNIDIRECTIONAL RANGE STATION.)
TWO-WAY RADIO COMMUNICATIONS FAILURE-
(See TRANSCRIBED WEATHER BROADCAST.)
(See LOST COMMUNICATIONS.)