T - true. Also TH, true heading, and TT, true track.

TACAN - tactical air navigation system. An ultra-high frequency electronic navigation
aid which provides suitably-equipped aircraft with a continuous indication of bearing
and distance to the selected Tacan station. The distance element can be received by
civilian DMF equipment, but otherwise Tacan is principally a military navaid.

TAF - Terminal Area Forecast.

TAS - true airspeed. Rectified airspeed corrected for altitude and outside air temperature.

TBO - time between overhauls, an engine manufacturer's recommended overhaul interval
in hours, a rough and not guaranteed guide to life expectancy of an aero-engine before it will
need overhaul.

TCA - Terminal Control Area (USA).

TCAS - traffic alert and collision avoidance system. U.S. developed radar-based airborne
collision avoidance system operating independently of ground-based equipment.
TCAS-I generates traffic advisories only, TCAS-II provides advisories and collision avoidance
instructions in the vertical plane.

TEMPO - temporarily, term used in Met reports.

TET - turbine entry temperature.

TGT - turbine gas temperarture.

THR or thld - threshold.

TMA - Terminal Control Area. An area of controlled airspace at the intersection of airways
in the vicinity of control zones (CTRs) around major airports.

TO - take-off (sometimes TKOF).

TODA - take-off distance available. Also TODR, take-off distance required, and TORA, take-off
run available.

track - actual flight path of an aircraft over the ground.

transition altitude (TA) - altitude in the vicinity of an aerodrome at or below which the
vertical position of an aircraft is controlled by reference to altitude, i.e. with the aerodrome