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From Pilots Almanac
From the FAA Pilot/Controller Glossary. Reference it for the original text. ICAO terms not included here.
Back to the Pilot/Controller Glossary Index.
TACAN
(See TACTICAL AIR NAVIGATION.)
TACAN-ONLY AIRCRAFT
An aircraft, normally military, possessing TACAN with DME but no VOR navigational system capability. Clearances must specify TACAN or VORTAC fixes and approaches.
TACTICAL AIR NAVIGATION
An ultra-high frequency electronic rho-theta air navigation aid which provides suitably equipped aircraft a continuous indication of bearing and distance to the TACAN station. (See VORTAC.)
TAILWIND
Any wind more than 90 degrees to the longitudinal axis of the runway. The magnetic direction of the runway shall be used as the basis for determining the longitudinal axis.
TAKEOFF AREA
(See LANDING AREA.)
TARGET
The indication shown on an analog display resulting from a primary radar return or a radar beacon reply. (See ASSOCIATED.) (See DIGITAL TARGET.) (See DIGITIZED RADAR TARGET.) (See PRIMARY RADAR TARGET.) (See RADAR.) (See SECONDARY RADAR TARGET.) (See TARGET SYMBOL.) (See UNASSOCIATED.)
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.
Note 1: MANDATORY TRAFFIC ADVISORIES AND SAFETY ALERTS SHALL BE ISSUED WHEN THIS PROCEDURE IS USED.
Note 2: 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.
TAS
(See TERMINAL AUTOMATION SYSTEMS.)
TAWS
(See TERRAIN AWARENESS WARNING SYSTEM.)
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. (See AIR TAXI.) (See HOVER TAXI.)
TAXI PATTERNS
Patterns established to illustrate the desired flow of ground traffic for the different runways or airport areas available for use.
TCAS
(See TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM.)
TCH
(See THRESHOLD CROSSING HEIGHT.)
TCLT
(See TENTATIVE CALCULATED LANDING TIME.)
TDLS
(See TERMINAL DATA LINK SYSTEM.)
TDZE
(See TOUCHDOWN ZONE ELEVATION.)
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.
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. (See APPROACH CONTROL FACILITY.) (See TOWER.)
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.
- 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 a TRSA.
- 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.)
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. (See NAVIGATIONAL AID.) (See VOR.)
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.
TETRAHEDRON
A device normally located on uncontrolled airports and used as a landing direction indicator. The small end of a tetrahedron points in the direction of landing. At controlled airports, the tetrahedron, if installed, should be disregarded because tower instructions supersede the indicator. (See SEGMENTED CIRCLE.)
TF
(See TERRAIN FOLLOWING.)
THAT IS CORRECT
The understanding you have is right.
360 OVERHEAD
(See OVERHEAD MANEUVER.)
THRESHOLD
The beginning of that portion of the runway usable for landing. (See AIRPORT LIGHTING.) (See DISPLACED THRESHOLD.)
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 GLIDESLOPE.) (See THRESHOLD.)
THRESHOLD LIGHTS
(See AIRPORT LIGHTING.)
TIBS
(See TELEPHONE INFORMATION BRIEFING SERVICE.)
TIME GROUP
Four digits representing the hour and minutes from the Coordinated Universal Time (UTC) clock. FAA uses UTC for all operations. The term "ZULU" may be used to denote UTC. The word "local" or the time zone equivalent shall be used to denote local when local time is given during radio and telephone communications. When written, a time zone designator is used to indicate local time; e.g. "0205M" (Mountain). The local time may be based on the 24-hour clock system. The day begins at 0000 and ends at 2359.
TMA
(See TRAFFIC MANAGEMENT ADVISOR.)
TMPA
(See TRAFFIC MANAGEMENT PROGRAM ALERT.)
TMU
(See TRAFFIC MANAGEMENT UNIT.)
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.
TOUCH-AND-GO
An operation by an aircraft that lands and departs on a runway without stopping or exiting the runway.
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
(See VISIBILITY.)
TOUCHDOWN ZONE
The first 3,000 feet of the runway beginning at the threshold. The area is used for determination of Touchdown Zone Elevation in the development of straight-in landing minimums for instrument approaches.
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. (See TOUCHDOWN ZONE.)
TOUCHDOWN ZONE LIGHTING
(See AIRPORT LIGHTING.)
TOWER
A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless of flight plan or weather conditions (IFR or VFR). A tower may also provide approach control services (radar or nonradar). (See AIRPORT TRAFFIC CONTROL SERVICE.) (See APPROACH CONTROL FACILITY.) (See APPROACH CONTROL SERVICE.) (See MOVEMENT AREA.) (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 communication requirements.
TOWER TO TOWER
(See TOWER EN ROUTE CONTROL SERVICE.)
TPX-42
A numeric beacon decoder equipment/system. It is designed to be added to terminal radar systems for beacon decoding. It provides rapid target identification, reinforcement of the primary radar target, and altitude information from Mode C. (See AUTOMATED RADAR TERMINAL SYSTEMS.) (See TRANSPONDER.)
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 or dual transducer AWOS, or portable pressure standards or DASI.
TRACK
The actual flight path of an aircraft over the surface of the earth. (See COURSE.) (See FLIGHT PATH.) (See ROUTE.)
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).
(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 INFORMATION
(See TRAFFIC ADVISORIES.)
TRAFFIC IN SIGHT
Used by pilots to inform a controller that previously issued traffic is in sight. (See NEGATIVE CONTACT.) (See TRAFFIC ADVISORIES.)
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.
- 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.) (See TAXI PATTERNS.)
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. (See USER REQUEST EVALUATION TOOL.)
TRAJECTORY MODELING
The automated process of calculating a trajectory.
TRANSCRIBED WEATHER BROADCAST
A continuous recording of meteorological and aeronautical information that is broadcast on L/MF and VOR facilities for pilots. (Provided only in Alaska.)
TRANSFER OF CONTROL
That action whereby the responsibility for the separation of an aircraft is transferred from one controller to another.
TRANSFERRING CONTROLLER
A controller/facility transferring control of an aircraft to another controller/facility.
TRANSFERRING FACILITY
(See TRANSFERRING CONTROLLER.)
TRANSITION
- 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. (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.
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). (See VISIBILITY.)
TRANSMITTING IN THE BLIND
A transmission from one station to other stations in circumstances where two-way communication cannot be established, but where it is believed that the called stations may be able to receive the transmission.
TRANSPONDER
The airborne radar beacon receiver/transmitter portion of the Air Traffic Control Radar Beacon System (ATCRBS) which automatically receives radio signals from interrogators on the ground, and selectively replies with a specific reply pulse or pulse group only to those interrogations being received on the mode to which it is set to respond. (See INTERROGATOR.)
TRANSPONDER CODES
(See CODES.)
TRIAL PLAN
A proposed amendment which utilizes automation to analyze and display potential conflicts along the predicted trajectory of the selected aircraft.
TRSA
(See TERMINAL RADAR SERVICE AREA.)
TSD
(See TRAFFIC SITUATION DISPLAY.)
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).
TVOR
(See TERMINAL-VERY HIGH FREQUENCY OMNIDIRECTIONAL RANGE STATION.)
TWEB
(See TRANSCRIBED WEATHER BROADCAST.)
TWO-WAY RADIO COMMUNICATIONS FAILURE
(See LOST COMMUNICATIONS.)
