TRANSCEIVER Type Rating
TRANSCEIVERS A device that receives and transmits
TRANSIENT-FREE SWITCH A switch with a wash-out filter so that the output contains no transients (steps) at switch time
TRANSMIT To radiate RF energy
TRANSMITTER A device that transmits
TRANSMITTER (TX) The hand-held radio controller. This is the unit that sends out the commands that you input.
TRANSPONDER Transmitter-Responder
TRANSPONDER (TX) A receiver/transmitter which will generate a reply signal upon proper interrogation; the interrogation and reply being on different frequencies.
TRE Type Rating Examiner
TREND MONITORING Continuous computerized observation of turbine engine performance. Used to detect early sings of wear.
TRI Type Rating Instructor
TRICYCLE GEAR The landing gear arrangement where the airplane has main gear and a nose gear.
TRIM To adjust an aircraft`s trim tabs and thereby relieve the pressure required on the controls to keep the nose in the desired position.
TRIM TAB A secondary control surface, usually mounted to primary control surface such as aileron, elevator, rudder, or stabilizer, that controls the position o...
TRK Track
TRN Terrain Referenced Navigation;
TRN-INS TRN with INS
TRTO Type Rating Training Organization
TRUE Best available estimate, such as true airspeed; referenced to true north, such as true heading;
TRUE AIRSPEED the airspeed of an aircraft relative to undisturbed air. True airspeed is equal to equivalent airspeed multiplied by (0/)1/2.
TRUE AIRSPEED (TAS) The airspeed of an aircraft relative to undisturbed air.
TRUE BEARING Symbols: B sub T; Typical Units: rad, deg;
TRUE HEADING Heading of the aircraft relative to true north; Symbols: psi sub T; Typical Units: rad, deg;
TRUE TRACK Ground track angle; Symbols: T sub T; Typical Units: rad, deg;
TSC Total Time Since CORE
TSMO Time since major overhaul
TSN Time Since New (also TTSN)
TSO Technical Standard Order
TT Total Time Airframe
TTG, TTS OR TTW Time to go, time to station, time to waypoint.
TUBA a jamming device for Freya radar operating in the 70-200 MHz range
TUNE To set the operating frequency or channel for a device
TURBO PROP Is said of an airplane powered by a type of jet engine, the turbo prop, equipped with a turbine-driven propeller.
TURBOJET AIRCRAFT An aircraft having a jet engine in which the energy of the jet operates a turbine which in turn operates the air compressor.
TURBOPROP AIRCRAFT An aircraft having a jet engine in which the energy of the jet operates a turbine which drives the propeller.
TURBULENCE MODE Flight control system mode in which a "softer" response to gust upsets is programmed.
TVOR very high frequency terminal omni range station.
TWR Tower (Control Tower)
TYPE (1) As used with respect to the certification, ratings, privileges, and limitations of airmen, means a specific make and basic model of aircraft, incl...
U Airspace Euro control project Class U (unknown traffic)
U/S unserviceable
U/V ADF UHF/VHF Automatic Direction Finding
UAT Universal Access Transceiver
UAV Unmanned (or Uninhabited) Aeronautical (or Aerial) Vehicle
UFN Until Further Notice
UFO Unidentified Flying Object
UHF Ultra High Frequencies (300 MHz-30 GHz)
UHF/VHF AUTOMATIC DIRECTIONFINDING (U/V ADF) An Automatic Direction Finder that determines relative bearing to a transmitter to which it is tuned, in either the UHF band or VHF band;
UL Ultra light, Ultra-l©ger motoris©
ULM Ultra light, Ultra-l©ger motoris©
ULTRALIGHT VEHICLE An aeronautical vehicle operated for sport or recreational purposes which does not require FAA registration, an airworthiness certificate, nor pilot c...
UMAS Unmanaged Air Space (Euro control Definition)
UNDER CAMBER This means that the lower surface of the wing has a hollow curve when observed from front to back. A thin wing with a high camber will be under camber...
UNDERCARRIAGE STRUT A part of an airplane`s structure, designed to resist distortion, which supports the landing gear.
UNIT FUNCTIONS A collection of functions used as standard test cases in control systems engineering; The primary unit functions of interest in avionics are the unit ...
UNIT IMPULSE A function used as a standard test case in control systems engineering; a spike of "area" one at time t = 0; Synonyms: impulse; See Also: unit functio...
UNIT LESS No units, such as ratios; a quantity with standard units of 1; a quantity with primary units of 1; Synonyms: dimensionless;
UNIT RAMP A function used as a standard test case in control systems engineering; a line of slope 1 starting at zero at time t = 0; Synonyms: ramp; See Also: un...
UNIT STEP A function used as a standard test case in control systems engineering; a step from zero to one at time t = 0; Synonyms: step; See Also: unit function...
UNITED STATES in a geographical sense, means (1) the States, the District of Columbia, Puerto Rico, and the possessions, including the territorial waters, and (2) t...
UNITED STATES AIR CARRIER a citizen of the United States who undertakes directly by lease, or other arrangement, to engage in air transportation.
UNITS A standard quantity, such as ft or mi; Synonyms: dimension;
UNIVERSAL TRANSVERSE MERCATOR(UTM) A system of fixed earth coordinates, sometimes used instead of latitude and longitude, accurate relative to others close by, such as ground troops;
UPDATE A process by which position is reset with a known better position; updates occur at the data source level or at the physical device level, depending u...
UPKEEP Codename for Barnes Wallis` bouncing bomb used in the Dambusters` raid
URB User Relations Bureau (CFMU)
USABLE FUEL (LBS) Usable fuel (gallons) x 6.7 lbs/gallon
USAF US Air Force
USEFUL LOAD Maximum Ramp Weight - (minus) Basic Operating Weight
USG (AL) US-Gallon (3.78 Liter)
UTC Universal Coordinated Time.
UTM Universal Transverse Mercator
V Universal Time Coordinated
V (X) Speed for best angle of climb.
V (Y) Speed for best rate of climb.
V1 speed for best angle of climb.
VA Maneuvering Speed (max. structural speed allowed for full control deflection)
VAC Volts alternating current.
VAL Visual Approach and Landing (Chart)
VAR Variation
VASI Visual Approach Slope Indicator
VAT Value Added Tax
VB design speed for maximum gust intensity.
VC design cruising speed.
VD Max. Dive Speed (for certification only)
VDB VHF Data Broadcast
VDC Volts direct current.
VDF demonstrated flight diving speed.
VDL VHF Data Link (-n = type n)
VEF the speed at which the critical engine is assumed to fail during takeoff.
VEHICLE/PEDESTRIAN DEVIATION(VPD) An entry or movement on an airport movement area by a vehicle operator or pedestrian that has not been authorized by air traffic control (includes air...
VELOCITY Rate of change of location, either scalar or vector, often with subscripts such as ENU or XYZ to denote the coordinate frame; time derivative of posit...
VELOCITY EAST Aircraft velocity in true east direction; Symbols: V sub E; Typical Units: kt, ft/s; Dimensions: Length / Time;
VELOCITY ERROR SCALE FACTOR(KVSF) A guidance control law parameter, generated by the longitudinal guidance modes;
VELOCITY NORTH Aircraft velocity in true north direction; Symbols: V sub N; Typical Units: kt, ft/s; Dimensions: Length / Time;
VENTRAL FIN A small vertical surface on the bottom of the aft fuselage. Usually a long, slim triangle that is narrow at the front, and widens toward the rear. It ...
VERT SPD Vertical speed hold
VERTICAL Reference to earth radial, for example, vertical velocity is velocity along earth radial; See Also: East-North-Vertical;
VERTICAL ACCELERATION Aircraft acceleration in earth vertical direction; Symbols: A sub V; Typical Units: ft/s-squared, g; Dimensions: Length / Time-squared;
VERTICAL CUE A cue to control altitude; See Also: yoke cue, collective cue;
VERTICAL GUIDANCE Calculations for the vertical axis, rather than the longitudinal axis. The control law vertical axis input data are: Desired Altitude, Altitude Integr...
VERTICAL SPEED HOLD (VERT SPD) A basic guidance mode, providing vertical guidance to maintain an operator selected vertical speed;
VERTICAL SPEED INDICATOR (VSI) An onboard instrument which gauges rate of climb or descent, in feet per minute.
VERTICAL VELOCITY Aircraft velocity in earth vertical direction; Symbols: V sub V; Typical Units: ft/s; Dimensions: Length / Time;
VF design flap speed.
VFE Max. Flaps Extended Speed
VFR Visual Flight Rules ("good" weather operations rules)
VFR OVER-THE-TOP with respect to the operation of aircraft, means the operation of an aircraft over-the-top under VFR when it is not being operated on an IFR flight pl...
VH maximum speed in level flight with maximum continuous power.
VHF Very High Frequency radio equipment.
VHF OMNI RANGE (VOR) Equipment that determines bearing to a radio station with a VOR transmitter; VOR transmitters usually contain ILS transmitters in addition to VOR; A b...
VILLAGE INN A gun laying radar installed in the rear-turret of some Lancaster bombers allowing blind-firing on an "illuminated" target
frequency at which the outp...
CVFR Controlled VFR (still existing in some countries)
CVR Cockpit Voice Recorder
CYCLES Pertaining to turbine engines. Cycle begins with starting, continues through full-power, and ends with shutdown.
CYCLIC See: longitudinal cyclic, lateral cyclic;
D Airspace ICAO Class D
D.R. DEAD RECKONING; system of navigation. VIS Very High Frequency (30-300 MHz)
VISUAL FLIGHT RULE (VFR) Rules that govern the procedures for conducting flight under visual conditions (VMC). The term is also used in the United States to indicate weather c...
VISUAL METEOROLOGICAL CONDITIONS(VMC) Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling equal to or better than specified minima.
VJAR-FCL Verordnung JAR-FCL (JAR-FCL transformed to Swiss Law)
VLA Very Light Aircraft (Aircraft certification category)
VLE Max. Landing Gear Extended Speed
VLF Very Low Frequency radio equipment
VLO Max. Landing Gear Operation Speed
VLOF lift-off speed.
VMC Visual Meteo Conditions ("good" weather for VFR or IFR)
VMO maximum operating limit speed.
VMU minimum unstick speed.
VNAV Vertical navigation, or the capability to compute pitch-axis maneuvers and altitude-related points in space.
VNE Never Exceed Speed
VNO Max. Structural Cruising Speed
VOR A ground-based electronic navigation aid transmitting very high frequency navigation signals, 360 degrees in azimuth, oriented from magnetic north. Us...
VOR/DME Vertical Navigation (GLS)
VORTAC VHF Omni range;
VR Rotation Speed
VS the stalling speed or the minimum steady flight speed at which the airplane is controllable.
VS0 Stalling Speed Landing Config
VS1 Stalling Speed in a specified Config.
VSSE Minimum Safe Single Engine Speed
VTOSS takeoff safety speed for Category A rotorcraft.
VX Best Angle of Climb Speed
VXSE Best Angle of Climb Speed, 1 engine inoperative
VY Best Rate of Climb Speed
VYSE Best Rate of Climb Speed, 1 engine inoperative
WA (IAOPA) World Assembly
WAAS GNSS wide-area augmentation system.
WANGANUI Colored flares dropped on H2S to sky mark a target
WARNING A signal which alerts the operator to a dangerous condition requiring immediate action (from MIL-STD-1472D); an annunciator that is the most critical ...
WARNING, CAUTION, ADVISORY (WCA) See: warning, caution, advisory, annunciator, alert;
WASH-OUT FILTER A filter to smooth a transition due to change of input source, such as when changing modes; See Also: transient-free switch;
WASHOUT The twist in an airfoil which causes less angle of attack at the tips than the root. For airplanes, this increases stability of the aircraft at slow s...
WASSERMANN German long range radar with a range of up to 190 Km.
WAYPOINT A predetermined geographical position used for route/instrument approach definition, or progress reporting purposes, that is defined relative to a VOR...
WAYPOINT (WYPT) A point on the ground, predefined as a point of interest for the flight; a basic guidance mode, providing lateral guidance to a waypoint, either by co...
WAYPOINT APPROACH To approach a waypoint
WCA Warning, Caution, Advisory
WEATHERVANE This describes the tendency to point into the wind. Stabilizers on a aircraft result in its desire to weathervane.
WEIGHT ON WHEELS (WOW) Indication of whether the aircraft has weight on its wheels, meaning airborne or on the ground; weight on wheels can be detected by a sensor on the wh...
WET WINGS Method for containing fuel in wings without using rubber fuel cells.
WGS-84 Wide Area Augmentation System
WGS72 World Geodetic Survey 1972
WGS84 World Geodetic Survey 1984
WHEEL A flight control operated by turning with hands in fixed-wing aircraft, primarily to control roll (heading) via the ailerons; wheel is connected to yo...
WHEEL CUE A lateral flight director cue for fixed-wing aircraft, primarily to control heading, by changing roll; Compare: lateral cyclic cue; Symbols: Gamma sub...
WHEEL PANTS The large fairings used to streamline the wheels of an aircraft that has non-retracting, or "fixed" landing gear (so-called because it`s "fixed" in pl...
WHITE BOMBS Nickname for propaganda leaflets.
WILDE SAU WILD BOAR. German ground- controlled night fighter system using twin engined aircraft
WIMPY RAF nickname for the Vickers Wellington bomber. The name came from J. Wellington Wimpy, a character in the Popeye cartoon in the Daily Mirror
WIMS System Wide Information Management
WIND BEARING Symbols: B sub W; Typical Units: rad, deg;
WIND SPEED Symbols: V sub W; Typical Units: kt, ft/s; Dimensions: Length / Time;
WINDOW Strips of silver paper dropped by British aircraft to confuse the German ground radars
WINDSOCK This can be used to describe a number of devices, all of which give a visual clue to the direction and speed of wind in a given location.
WING The main lifting surface of an airplane.
WING FENCE Term preferred by Airbus and McDonnell-Douglas aircraft manufacturers for the vertical structures at the outside ends of the wings of some of their je...
WING LOADING This is the amount of weight per square foot that has to be overcome to provide lift. It is normally expressed in ounces per square foot. This specifi...
WING ROOT The centerline of the wing, where the left and right wing panels are joined.
WINGLET A small vertical surface at the tips of the wings. They help direct the turbulent airflow that all wings have at the tips. They makes the wings more e...
WIP Work in Progress
WMO World Meteorological Organization
WORLD GEODETIC SURVEY 1972 (WGS72) A standard model for computing earth data;
WORLD GEODETIC SURVEY 1984 (WGS84) A standard model for computing earth data;
WOW Weight on wheels
WP Waypoint
WPT Waypoint
WRAP TEST A test to send data to a device having it sent back unaltered
WWII Waypoint
WX Weather
WYPT Waypoint
WœRZBURG German short (11 mile) range gun laying radar capable of giving both height and range.
X-BAND Frequency range in which most general aviation weather radars operate.
X-BEAMS German radio beams used to guide their bombers to the target
XPDR Transponder. Radar-enhancement/data link box for ATC purposes.
XPOND Transponder
XTK Cross track; cross track error.
XTKD Cross track deviation
XTKR Cross track deviation rate
XYZ A standard aircraft coordinate frame and sign convention, where nose, right wing, and down are positive X, Y, and Z, respectively; often used as subsc...
Y-BEAMS German radio beams used to guide their bombers to the target
Y-SERVICE British organization for the interception and reporting of German wireless "chatter" for intelligence purposes.
Y2K Year-2000 (computer date problem) NOTE: k=decimal kilo=1000 (1-1000); thus Y2k=2000 K=binary kilo=1024 (0-1023); thus Y2K=2047
YAW The nose-left and nose-right movement of the airplane. This is controlled by the rudder.
YAW AXIS The airplane axis controlled by the rudder. Yaw is illustrated by hanging the airplane level by a wire located at the center of gravity. Left or right...
YAW RATE The rate of movement about the vertical axis of a aircraft.
YOKE CUE A vertical flight director cue for fixed-wing aircraft, primarily to control altitude, by changing pitch; Compare: collective cue; Symbols: Gamma sub ...
Z Infra-red identification equipment
Z TRANSFORM A mathematical relationship to model a discrete function in the complex frequency domain (Z-plane); Z transforms are commonly used by systems engineer...
Z-BEND A type of linkage point using a bend in the control rod which resemble a Z.
Z-PLANE Discrete complex frequency plane; Z-plane is used in control systems engineering in the design of control laws See Also: Z transform;
ZAHME SAU TAME BOAR. German "free lance" night fighter system using single engined aircraft
ZERST–RER GESHWADER Luftwaffe Destroyer Wings, composed of Bf110 Heavy fighters
ZOC Zone of confusion
ZONE OF CONFUSION (ZOC) A circular area centered at a TACAN station in which bearing is extremely noisy;
ZULU Greenwich Mean Time, also known as Universal Coordinated Time.
