true. Also TH, true heading, and TT, true track.
TACAN - tactical air navigation system. An ultra-high frequency
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
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
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
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 temperature.
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
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
QNH set on its
altimeter. Above transition altitude QNE is set and flight levels
Also transition level (TL) at which a descending aircraft changes from
FL to QNH.
transponder - An electronic device that "responds" to
interrogation by ground-based radar with a special four-digit code
that specifically identifies the aircraft on which it is located.
Certain transponders have the ability to transmit automatically the
altitude of the aircraft in addition to the special code.
trend - Met forecast for the next two hours, added to some
TSO - Technical Standard Order. A standard established by the
U.S. FAA for quality
control in avionics, instruments and other airborne equipment. If it
is said to be 'TSO'd' and is more expensive than similar non-TSO's
TVOR - terminal VOR. A low-powered VOR located at or near an
airport and used as an approach aid.
TWR - Tower (aerodrome control tower).
TWY - taxiway.
Tx - transmitter.