- t Tonne, 1 Megagram, 1,000 kg.
- tab Small auxiliary surface hinged (flight-adjustable) or attached in a fixed position (ground-adjustable) to trailing-edge of control surface for trimming, balancing (reducing hinge moment: force needed to operate main surface) or in other way assisting pilot. Compare anti-balance tab.
- tabbed flap Fitted with narrow-chord tab along trailing-edge which deflects to greater angle than main surface.
- Tacan Tactical air navigation, UHF navaid giving bearing and distance to ground beacons; distance element (see DME) can be paired with civil VOR.
- talleron Left and right tailplanes used as primary control surfaces in both pitch and roll.
- tailplane Horizontal stabiliser; main horizontal tail surface, originally fixed and carrying hinged elevator(s) but today often a single 'slab' serving as control surface (see stabiliser, stabilator).
- TANS Tactical air navigation system; Decca Navigator or Doppler-based computer, control and display unit.
- TAS True airspeed, EAS corrected for density (often very large factor) appropriate to aircraft altitude.
- TBO Time between overhauls.
- t/c ratio Ratio of the thickness (aerodynamic depth) of a wing or other surface to its chord, both measured at the same place parallel to the fore-and-aft axis.
- TCAS Traffic-alert and collision-avoidance system.
- Tercom Terrain-comparison (or contour-matching), navigation aid which compares relief of terrain with profile stored in memory.
- TFR Terrain-following radar (for low-level attack).
- thickness Depth of wing or other aerofoil; maximum perpendicular distance between upper and lower surfaces.
- thrust vectoring Rotation of a vehicle's thrust axis to control its trajectory or support its weight.
- TIALD Thermal imaging and laser designation (pod).
- tiltrotor Aircraft with fixed wing and rotors that tilt up for hovering and forward for fast flight.
- T-O Take-off.
- T-O noise EPNdB measure of aircraft taking off, at point directly under flight path 3.5 n miles from brakes-release.
- TOGW Take-off gross weight (not necessarily MTOW).
- ton Imperial (long) ton = 1.016 t or 2,240 lb, US (short) ton = 0.9072 t or 2,000 lb.
- track Distance between centres of contact areas of main landing wheels measured left/right across aircraft (with bogies, distance between centres of contact areas of each bogie).
- transceiver Radio transmitter/receiver.
- transformer-rectifier Device for converting AC to DC at a different voltage.
- transponder Radio transmitter triggered automatically by a particular received signal, as in secondary surveillance radar (SSR).
- TsENTROSPAS (in Russian Federation) Ministry for Civil Defence, Emergencies and Elimination of the Consequences of Natural Disasters.
- turbofan Gas-turbine jet engine generating most thrust by a large-diameter cowled fan, with small part added by jet from core.
- turbojet Simplest form of gas turbine comprising compressor, combustion chamber, turbine and propulsive nozzle.
- turboprop Gas turbine in which as much energy as possible is taken from gas jet and used to drive reduction gearbox and propeller.
- turboshaft Gas turbine in which as much energy as possible is taken from gas jet and used to drive high-speed shaft (which in turn drives external load such as helicopter transmission).
- twist Progressive change of angle of incidence of a wing, rotor blade or other aerofoil from root to tip.
- Type Certificate Airworthiness licence granted to enable a manufacturer to produce and market a specified type of aircraft (compare C of A).
- tyre sizes Five systems of classification are in current use; Type I, consisting of a single figure indicating nominal diameter in inches, is obsolete. See adjacent table and also 'ply'.
