- T -

TA - Traffic advisory (TCAS).

TACAN - Terrain avoidance.

TACHOMETER - An optical sensor designed specifically to count light impulses through a turning propeller and read out the engine RPM.

TAIL DRAGGER - The nickname of an airplane that sits on its tail with the two main wheels in front and a tail wheel in the rear.

TAIL WHEEL - The small wheel at the tail of the airplane. This is found on the type of airplane that has the two large wheels in the front, and the small one in the rear. The airplane sits on its tail.

TAILSKID - On old World War I type aircraft, or pioneer-type aircraft, there was no tail wheel. A wooden skid was used to support the tail of the airplane. While this helps slow the airplane during landing, it is useless as an aid to steering on the ground. The real aircraft with tailskids had to be maneuvered on the ground by ground crews, who put the tail on a small cart and towed the airplane where they wanted it. For small distances, the tail was picked-up by hand and the airplane pushed into position by the ground crew.

TAKEOFF POWER - (1) With respect to reciprocating engines, means the brake horsepower that is developed under standard sea level conditions, and under the maximum conditions of crankshaft rotational speed and engine manifold pressure approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification; and (2) With respect to turbine engines, means the brake horsepower that is developed under static conditions at a specified altitude and atmospheric temperature, and under the maximum conditions of rotor shaft rotational speed and gas temperature approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification

TAKEOFF SAFETY SPEED - a referenced airspeed obtained after lift-off at which the required one-engine-inoperative climb performance can be achieved.

TAKEOFF THRUST - with respect to turbine engines, means the jet thrust that is developed under static conditions at a specific altitude and atmospheric temperature under the maximum conditions of rotor shaft rotational speed and gas temperature approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification. Tandem wing configuration means a configuration having two wings of similar span, mounted in tandem.

TARMAC - A bituminous material used in paving.

TAXI - The movement of an airplane under its own power on the surface of an airport.

TAXIWAY - A road leading from the airplane parking area to the runway; always marked with yellow lines.

TBO - Time between overhaul.

TCAS - Traffic alert and Collision Avoidance System.

TCH - Threshold Crossing Height.

TDZL - touchdown zone lights.

TRUE AIRSPEED (TAS) - An air speed indicator indicates air speed only under standard sea-level conditions, thus, true airspeed is usually calculated by adjusting an indicated air speed according to temperature, density and pressure.

TERMINAL RADAR SERVICE AREA (TRSA) - Airspace surrounding designated airports wherein ATC provides radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft. Service provided at a TRSA is called Stage III Service. TRSA`s are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.

TETRAHEDRON - Ground-based, free-rotating, triangular-shaped wind direction indicator generally placed near a runway for reference by pilots.

THRUST - The driving force of a propeller in the line of its shaft or the forward force produced in reaction to the gases expelled rearward from a jet or rocket engine (opposite to drag).

TORQUE - A twisting, gyroscopic force acting in opposition to an axis of rotation, such as with a turning propeller.

TOUCH-AND-GO - Landing practice wherein an aircraft does not make a full stop after a landing, but proceeds immediately to another take-off.

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.

TRAFFIC PATTERN - The traffic flow that is prescribed for aircraft landing at, taxiing on, or taking off from, an airfield.

TRAILING EDGE - The rearmost edge of an airfoil.

TRANSCEIVER - A device that receives and transmits.

TRANSMIT - To radiate RF energy.

TRANSMITTER - A device that transmits.

TRANSPONDER - An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position and altitude information than would be possible with "passive" radar.

TREND MONITORING - Continuous computerized observation of turbine engine performance. Used to detect early signs of wear.

TRIM - Device in an aircraft designed to relieve the pressure required on the controls to keep the nose in the desired position.

TRIM TAB - A small, auxiliary control surface in the trailing edge of a wing form, adjustable mechanically or by hand, to counteract or trim aerodynamic forces that act on the main control surfaces.

TRUE AIRSPEED - The speed of an aircraft along its flight path, in respect to the body of undisturbed air, or air mass through which the aircraft is moving.

TRUE - Heading of the aircraft relative to true north.

TRUE NORTH - The northern direction of the axis of the earth (geographic north).

TURBOJET - An aircraft having a jet engine in which the energy of the jet operates a turbine that in turn operates the compressor.

TURBOPROP - An aircraft having a jet engine in which the energy of the jet operates a turbine that drives the propeller.

T/O - take-off.

T/RS - Thrust Reversers.

TYPE (1) - As used with respect to the certification, ratings, privileges, and limitations of airmen, means a specific make and basic model of aircraft, including modifications thereto that do not change its handling or flight characteristics. Examples include: DC-7, 1049, and F-27; and

TYPE (2) - As used with respect to the certification of aircraft, means those aircraft which are similar in design. Examples include: DC-7 and DC-7C; 1049G and 1049H; and F-27 and F-27F.

TYPE (3) - As used with respect to the certification of aircraft engines means those engines which are similar in design. For example, JT8D and JT8D-7 are engines of the same type, and JT9D-3A and JT9D-7 are engines of the same type.