Aeronautical Terms beginning with T
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
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.
Takeoff Area
Landing Area.
Takeoff Distance Available (TODA)
The takeoff run available plus the length of any remaining runway or clearway beyond the far end of the takeoff run available.
Takeoff Run Available (TORA)
The runway length declared available and suitable for the ground run of an airplane taking off.
Target
The indication shown on an analog display resulting from a primary radar return or a radar beacon reply.
Target Resolution
A process to ensure that correlated radar targets do not touch. Target resolution must be applied as follows: a. Between the edges of two primary targets or the edges of the ASR-9/11 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. Note 1: Mandatory traffic advisories and safety alerts must be issued when this procedure is used. Note 2: This procedure must not be used when utilizing mosaic radar systems or multi-sensor mode.
Target Symbol
A computer-generated 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.
Tarmac Delay
The holding of an aircraft on the ground either before departure or after landing with no opportunity for its passengers to deplane.
Tarmac Delay Aircraft
An aircraft whose pilot-in-command has requested to taxi to the ramp, gate, or alternate deplaning area to comply with the Three-hour Tarmac Rule.
Tarmac Delay Request
A request by the pilot-in-command to taxi to the ramp, gate, or alternate deplaning location to comply with the Three-hour Tarmac Rule.
Taxi
The movement of an airplane under its own power on the surface of an airport (14 CFR Section 135.100 [Note]). Also, it describes the surface movement of helicopters equipped with wheels.
Taxi Patterns
Patterns established to illustrate the desired flow of ground traffic for the different runways or airport areas available for use.
Telephone Information Briefing Service
A continuous telephone recording of meteorological and/or aeronautical information. Discontinued in the CONUS in September 2018 and in Alaska on Jan 1, 2020.
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.
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 aircraft.
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 (Initial Approach Fix). TAAs will also eliminate or reduce feeder routes, departure extensions, and procedure turns or course reversal.
Terminal Automation Systems (TAS)
TAS is used to identify the numerous automated tracking systems including ARTS IIE, ARTS IIIA, ARTS IIIE, STARS, and MEARTS.
Terminal Data Link System (TDLS)
A system that provides Digital Automatic Terminal Information Service (D-ATIS) both on a specified radio frequency and also, for subscribers, in a text message via data link to the cockpit or to a gate printer. TDLS also provides Pre-departure Clearances (PDC), at selected airports, to subscribers, through a service provider, in text to the cockpit or to a gate printer. In addition, TDLS will emulate the Flight Data Input/Output (FDIO) information within the control tower.
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. TRSAs are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.
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 Directory.
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 Awareness Warning System (TAWS)
An on-board, terrain proximity alerting system providing the aircrew `Low Altitude warnings’ to allow immediate pilot action.
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 obstruction.
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.”
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.
That Is Correct
The understanding you have is right.
Three-Hour Tarmac Rule
Rule that relates to Department of Transportation (DOT) requirements placed on airlines when tarmac delays are anticipated to reach 3 hours.
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.
Threshold Lights
Airport Lighting.
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.
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.
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 take-off 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.
Touch-And-Go Landing
Touch-And-Go.
Touchdown
A. The point at which an aircraft first makes contact with the landing surface.
B. Concerning a precision radar approach (PAR), it is the point where the glide path intercepts the landing surface.
Touchdown RVR
The RVR visibility readout values obtained from RVR equipment serving the runway touchdown zone.
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 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
Airport Lighting.
Touchdown Zone [ICAO]
The portion of a runway, beyond the threshold, where it is intended landing aircraft first contact the runway.
Touchdown [ICAO]
The point where the nominal glide path 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.
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).
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 communication requirements.
Tower To Tower
Tower En Route Control Service.
Trace Icing
Ice becomes perceptible. Rate of accumulation is slightly greater than the rate of sublimation. Deicing/anti-icing equipment is not utilized unless encountered for an extended period of time (over 1 hour).
Traceable Pressure Standard
The facility station pressure instrument, with certification/calibration traceable to the National Institute of Standards and Technology. Traceable pressure standards may be mercurial barometers, commissioned ASOS/AWSS or dual transducer AWOS, or portable pressure standards or DASI.
Track
The actual flight path of an aircraft over the surface of the earth.
Track Of Interest (TOI)
Displayed data representing an airborne object that threatens or has the potential to threaten North America or National Security. Indicators may include, but are not limited to: noncompliance with air traffic control instructions or aviation regulations; extended loss of communications; unusual transmissions or unusual flight behavior; unauthorized intrusion into controlled airspace or an ADIZ; noncompliance with issued flight restrictions/security procedures; or unlawful interference with airborne flight crews, up to and including hijack. In certain circumstances, an object may become a TOI based on specific and credible intelligence pertaining to that particular aircraft/object, its passengers, or its cargo.
Track Of Interest Resolution
A TOI will normally be considered resolved when: the aircraft/object is no longer airborne; the aircraft complies with air traffic control instructions, aviation regulations, and/or issued flight restrictions/security procedures; radio contact is re-established and authorized control of the aircraft is verified; the aircraft is intercepted and intent is verified to be nonthreatening/nonhostile; TOI was identified based on specific and credible intelligence that was later determined to be invalid or unreliable; or displayed data is identified and characterized as invalid.
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).
Traffic
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: 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/her 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/she should not assume that all traffic will be issued.
Traffic Alert
(aircraft call sign), TURN (left/right) IMMEDIATELY, (climb/descend) AND MAINTAIN (altitude).
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.
Traffic Information
Traffic Advisories.
Traffic Information Service-Broadcast (TIS-B)
The broadcast of ATC derived traffic information to ADS-B equipped (1090ES or UAT) aircraft. The source of this traffic information is derived from ground-based air traffic surveillance sensors, typically from radar targets. TIS-B service will be available throughout the NAS where there are both adequate surveillance coverage (radar) and adequate broadcast coverage from ADS-B ground stations. Loss of TIS-B will occur when an aircraft enters an area not covered by the GBT network. If this occurs in an area with adequate surveillance coverage (radar), nearby aircraft that remain within the adequate broadcast coverage (ADS-B) area will view the first aircraft. TIS-B may continue when an aircraft enters an area with inadequate surveillance coverage (radar); nearby aircraft that remain within the adequate broadcast coverage (ADS-B) area will not view the first aircraft.
Traffic Management Advisor (TMA)
A computerized tool which assists Traffic Management Coordinators to efficiently schedule arrival traffic to a metered airport, by calculating meter fix times and delays then sending that information to the sector controllers.
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.
Traffic Management Unit
The entity in ARTCCs and designated terminals directly involved 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.
Traffic Situation Display (TSD)
TSD 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 en route sector boundaries, fixes, airways, military and other special use airspace, airports, and geopolitical boundaries. By using the TSD, a coordinator can monitor any number of traffic situations or the entire systemwide traffic flows.
Trajectory
A URET representation of the path an aircraft is predicted to fly based upon a Current Plan or Trial Plan.
Trajectory Modeling
The automated process of calculating a trajectory.
Transfer Of Control
That action whereby the responsibility for the separation of an aircraft is transferred from one controller to another.
Transfer Of Control [ICAO]
Transfer of responsibility for providing air traffic control service.
Transferring Controller
A controller/facility transferring control of an aircraft to another controller/facility.
Transferring Facility
Transferring 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. Note: See definition of accepting unit/controller.
Transition
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.
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.
Transition Waypoint
The waypoint that defines the beginning of a runway or en route transition on an RNAV SID or STAR.
Transitional Airspace
That portion of controlled airspace wherein aircraft change from one phase of flight or flight condition to another.
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 value (RVV).
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 Codes
Codes.
Transponder Observed
Phraseology used to inform a VFR pilot the aircraft’s assigned beacon code and position have been observed. Specifically, this term conveys to a VFR pilot the transponder reply has been observed and its position correlated for transit through the designated area.
Transponder [ICAO]
A receiver/transmitter which will generate a reply signal upon proper interrogation; the interrogation and reply being on different frequencies.
Trial Plan
A proposed amendment which utilizes automation to analyze and display potential conflicts along the predicted trajectory of the selected aircraft.
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.
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.”
True Course
A predetermined desired course direction to be followed (measured in degrees from true north).
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).
Two-Way Radio Communications Failure
Lost Communications.
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