Glossary of Aviation Terminology

A , B , C , D , E , F , G , H , I , J - K , L , M , N , O , P , Q - R , S , T , U , V, W, X - Z

TA: Terrain avoidance

TACAN: Tactical Air Navigation;

TACAN Point-to-Point (TCNP): A basic guidance mode, providing lateral guidance to a point relative to a TACAN station by specified range and bearing;

Tachometer: A device for measuring angular velocity;

Tactical Air Navigation (TACAN): A basic guidance mode, providing lateral guidance to a TACAN station; Equipment that determines range and bearing to a radio station with a TACAN transmitter;

TAE: Track angle error

Target: Object or point pointed by FLIR or radar

Target cursor: A symbol on a display, moved by a track handle or similar device, to select objects on the display

TAS: True airspeed

Taut line: Basic guidance mode; provides vertical guidance to maintain a taut line for a dipping sonar, or other such device.

TCN: Tacan

TCNP: Tacan Point-to-Point

Terrain: The contour of the earth;

Terrain avoidance (TA): Flight such that the aircraft maintains a constant barometric altitude but flies around obstacles; Compare: obstacle avoidance, threat avoidance;

Terrain following (TF): A basic guidance mode, providing vertical guidance to maintain an operator selected radar altitude above the terrain. Flight such that the aircraft tries to maintain a constant height above the terrain, usually in the range of 100-1,000 ft; Uses a g-command from the Multi-Mode Radar to generate a flight director cue. This controls the aircraft flight path so that the set clearance altitude is achieved over major high points in the terrain with zero flight path angle. Compare: nap-of-the-earth flight;

Terrain Referenced Navigation (TRN): A navigation mode based on comparison of barometric altitude and radar altitude with a map; Kalman filters correlate the terrain data and the altitudes. A primary navigation data source. TRN combines INS with map references. It is most accurate over rough terrain. Does not give accurate data while over flat areas or water. See Also: Digital Map Generator;

Test status words: Status words reported at the conclusion of a test. Values: test in progress, not tested, normal, redundant, degraded, failed;

TF: Terrain following;

ThA: Threat avoidance

Threat avoidance (ThA): Flight cues designed to avoid enemy threats, such as anti-aircraft artillery and aircraft; Compare: obstacle avoidance, terrain avoidance;

Throttle: A flight control operated by moving fore or aft with hands, primarily to control thrust (speed) in fixed-wing aircraft;

Throttle cue: A longitudinal flight director cue for fixed-wing aircraft, primarily to control speed, by changing power; Compare: longitudinal cyclic cue; Symbols: Gamma sub LONG; Typical Units: percent,in;

Thrust: Force, created by engines and rotors, acting in the direction of the engine; Symbols: T; Typical Units: lbf,kip; Dimensions: Mass * Length / Time-squared;

Tilt rotor: An aircraft with tilting rotors for fixed-wing flight or rotary-wing flight;

Time constant: Constant for a first-order filter determining time at which the output of the filter reaches nearly 0.6321 percent of a step input; Symbols: tau; Typical Units: s; Dimensions: Time;

Tolerances: Allowed error in measurements

Total pressure: A measure of barometric pressure in the moving air; Synonyms: dynamic pressure, Pitot pressure, stagnation pressure; Compare: static pressure; Symbols: p sub t; Typical Units: psi,lbf/in-squared; Dimensions: Mass /Time-squared * Length

Track (TRK): A basic guidance mode, providing lateral guidance to an operator selected ground track;

Track angle error (TAE): A guidance control law parameter, generated by the lateral guidance modes; Typical Units: rad;

Track angle error gain (KTAE): A guidance control law parameter, generated by the lateral guidance modes;

Track handle: A device to move a cursor in two axes on a display, much like a mouse

Tracking: Tracking is performed by the TRN

Transceivers: A device that receives and transmits

Transient-free switch: A switch with a wash-out filter so that the output contains no transients (steps) at switch time

Transmit: To radiate RF energy

Transmitter: A device that transmits

Trim tab: A secondary control surface, usually mounted to primary control surface such as aileron, elevator, rudder, or stabilizer, that controls the position of the primary control surface, and is controlled by the an operator or an autopilot; Symbols: delta sub T; Typical Units: rad, deg;

TRK: Track

TRN: Terrain Referenced Navigation;

True: Best available estimate, such as true airspeed; referenced to true north, such as true heading;

True airspeed (TAS): Airspeed corrected for instrumentation errors and air density; See Also: airspeed; Symbols: V sub 'TAS'; Typical Units: kt,ft/s; Dimensions: Length / Time;

True bearing: Symbols: B sub T; Typical Units: rad, deg;

True heading: Heading of the aircraft relative to true north; Symbols: psi sub T; Typical Units: rad, deg;

True track: Ground track angle; Symbols: T sub T; Typical Units: rad, deg;

Tune: To set the operating frequency or channel for a device

A , B , C , D , E , F , G , H , I , J - K , L , M , N , O , P , Q - R , S , T , U , V, W, X - Z