Terminal aerodrome forecast (TAF).  A report established for the 5 statute mile radius around an airport. Utilizes the same descriptors and abbreviations as the METAR report. 

Terminal Radar Service Area (TRSA).  Area where participating pilots can receive additional radar services, the purpose of which is to provide separation between all IFR operations and participating VFR aircraft. 

TFR. See temporary flight restriction. 

Thermal. A buoyant plume or bubble of rising air. 

Throttle.  The control in an aircraft that regulates the power or thrust the pilot wants the engine to develop from the valve in a carburetor or fuel control unit that determines the amount of fuel-air mixture that is fed to the engine. 

Thrust. The force which imparts a change in the velocity of a mass. A forward force which propels the WSC through the air. 

Thrust line.  An imaginary line passing through the center of the propeller hub, perpendicular to the plane of the propeller rotation. 

Title 14 of the Code of Federal Regulations (14 CFR). That portion of the code formerly called the Federal Aviation Regulations (FAR) governing the operation of aircraft, airways, and airmen. 

Torque. (1) A resistance to turning or twisting. (2) Forces that produce a twisting or rotating motion. (3) In a WSC, the tendency of the aircraft to turn (roll) in the opposite direction of rotation of the engine and propeller. 

Total drag. The sum of the parasite and induced drag. 

Touch and go.  An operation by an aircraft that lands and takes off without stopping. 

Touchdown point. The point or intended point at which an aircraft first makes contact with the landing surface. 

Touchdown zone. The portion of a runway, beyond the threshold, where it is intended landing aircraft first contact the runway. 

Towered airport. An airport that has an operating control tower. 

Track. The actual path made over the ground in flight. 

Traffic pattern. The traffic flow that is prescribed for aircraft landing at or taking off from an airport. 

Traffic pattern indicators.  Ground based visual indicators that identify traffic pattern direction at certain airports. 

Trailing edge. The aft edge of the airfoil. In normal flight, it is the portion of the airfoil where airflow over the upper surface rejoins the lower surface airflow. 

Training bars. An attachment to the control frame which allows the instructor in the rear seat to move the control bar and control the pitch and bank with a solid attachment. 

Transponder. The airborne portion of the secondary surveillance radar system. The transponder emits a reply when queried by a radar facility. 

Tricycle gear configuration.  Landing gear configuration employing a third wheel located on the nose of the aircraft. 

True airspeed. Actual airspeed, determined by applying a correction for pressure altitude and temperature to the CAS. Because air density decreases with an increase in altitude, an airplane has to be flown faster at higher altitudes to cause the same pressure difference between pitot impact pressure and static pressure. Therefore, for a given calibrated airspeed, true airspeed increases as altitude increases; or for a given true airspeed, calibrated airspeed decreases as altitude increases. 

True altitude. The vertical distance of the airplane above sea level. the actual altitude. It is often expressed as feet above mean sea level (MSL). Airport, terrain, and obstacle elevations on sectional charts are true altitudes. 

TRSA.  See Terminal Radar Service Area. 

Tuck.  A nose down situation in a WSC where the pitch angle is over 90 degrees down resulting from a whip stall or severe turbulence. 

Tumble. The WSC rotating uncontrollably around its lateral axis from a whip stall or severe turbulence. Results of a tumble would probably cause a structural failure with catastrophic consequences. 

Turbulence. An occurrence in which a flow of fluid is unsteady. 

Twist.  The design of the WSC wing in which a wing is twisted so its angle of attack is less at the tip than at the root. 

