TSA Tail Strike Assembly
TSE Total System Error
TSM Autothrottle Servo Mount (without Clutch)
TSO Technical Standard Order. Every unit built with a TSO
nameplate must meet TSO requirements. TSO operat-
ing temperature extremes are not the same as the
manufacturing burn-in limits.
TTFF Time To First Fix
TTL Transistor - Transistor Logic
TTR TCAS II Receiver/Transmitter
TTS Time To Station,an indication that displays the
amount of time for an aircraft to reach a selected
DME ground station while traveling at a constant
speed.
TTY Teletypewriter
TURB Turbulence
Turbulence The US National Weather Service defines light turbu-
lence as areas where wind velocity shifts are 0 to 19
feet per second (0 to 5.79 metres per second) and
moderate turbulence as wind velocity shifts of 19 to
35 feet per second (5.79 to 10.67 metres per second).
TVBC Turbine Vane and Blade Cooling
TVC Turbine Vane Cooling
TWDL Two Way Data Link
TWIP Terminal Weather Information for Pilots
TWT Traveling Wave Tube TX Transmit (see XMIT)
U
UART Universal Asynchronous Receiver/Transmitter UAL United Airlines UB Utility Bus UBI Uplink Block Identifier UCS Uniform Chromaticity Scale UD User Data. The N-User data may also be transferred
between peer network members (OSI Model) as required.
UFDR Universal Flight Data Recorder UHF Ultra-High Frequency. The portion of the radio spec-
trum from 300 MHz to 3 GHz. ULB Underwater Locator Beacon ULD Unit Load Device UMT Universal Mount
Unpaired A DME channel without a corresponding VOR or ILS Channel frequency.
Uplink The radio transmission path upward from the earth to the aircraft.
UPS Uninterruptible Power System
USAF United States Air Force
USB Upper Sideband is the information-carrying band and is the frequency produced by adding the carrier fre-quency and the modulating frequency.
USGIC U.S.GPS Industry Council USTB Unstabilized UTC Universal Coordinated Time UUT Unit Under Test
UV Upper Sideband Voice UW Unique Word
V
V1 Critical engine failure velocity
V2 Takeoff climb velocity
VA Volt-Amperes
VAC Volts AC
VAP Visual Aids Panel
VAPS (1) Virtual Avionics Prototyping System
(2)
Virtual Applications Prototyping System VAU Voltage Averaging Unit VBV Variable Bypass Valve VCCS Voice Communication Council System VCD (1) Voltage Controlled Device
(2)
Variable Capacitance Diode VCO Variable Controlled Oscillator VDC Volts Direct Current VDL VHF Data Link VDOP Vertical Dilution of Precision VDR VHF Data Radio Vertical Speed The rate of change of pressure altitude,usually cali-
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