A -
A Autotuned NAVAID
A At or Above (constrained altitude)
AA American
AAATS Australian Advanced Air Traffic Services 
AAC Aeronautical Administration Communication (a class of communication which supports administrative communication)
AAS Advanced Automation System (the end systems for all FAA air traffic control, located at the ARTCCs)
AATT Advanced Aviation Transportation Technology
ABM Abeam
A/C Aircraft
AC Air Canada
ACARS Aircraft Communications Addressing and Reporting System
ACARS ARINC communications and address reporting system (digital communications system used primarily for aircraft-to-airline messages)
ACARS MU ACARS Management Unit
ACAS Airborne Collision and Avoidance System
ACF Area Control Facility
ACFS Advanced Concepts Flight Simulator (a generic "glass cockpit")
ACK Acknowledge
ACMS Aircraft Condition Monitoring System 
ACT Active 
ADC Air Data Computer 
ADF Automatic Direction Finder 
ADI Attitude Director lndicator
ADLP Aircraft Data Link Processor (the Mode S subnetwork function onboard the aircraft that implements the OSI network layer protocols)
ADMA Aviation Distributors and Manufactureres Association
ADS Automatic Dependent Surveillance 
AECB Atomic Energy Control Board 
AERA Automated Enroute ATC 
AFCS Automatic Flight Control System 
AFDS Autopilot Flight Director System (also A/P F/D) 
AFS Automatic Flight System
AGATE Advanced General Aviation Transport Experiments 
AGL Above Ground Level 
AHRS Attitude Heading Reference System
AIRS Advanced Infrared Sounder 
A/l Anti-ice
AI Artificial Intelligence
AL Allegheny
Alert Indicator (visual or auditory) which provides information to the flightcrew in a timely manner about an event requiring pilot awareness.
ALPA Air Line Pilots Association 
ALT Altitude 
ALT Alternate 
ALTN Alternate 
ALT HOLD Altitude Hold Mode
AM Amplitude Modulation 
AM Aeromexico
AMSS Aeronautical Mobile Satellite Service 
ANA All Nippon Airways 
AOA Angle-of-Attack
AOA Airport Operations Area
AOC Aeronautical Operation Control (communications which support safety and regularity of flight that normally take place between aircraft and the operator)
AOCS Attitude and Orbit Control System
AOM Aircraft Operating Manual
AOPA Aircraft Owners and Pilots Association 
A/P Autopilot
APA Allied Pilots Association
APC Aeronautical Passenger Communication (a class of communication which supports passenger communication)
APMS Automated Performance Measurement System 
APPR Approach/Approach Mode 
APR April 
APRT Airport
APU Auxiliary Power Unit
AQP Advanced Qualification Program
ARAC Aviation Rulemaking Advisory Committee 
ARINC Aeronautical Radio Incorporated
ARPA Advanced Research Projects Agency 
ARR Arrival
ARTCC Air Route Traffic Control Center
ARTS Automated Radar Terminal System 
ASCII American Standard Code for Interface and Interchange 
ASI Air Speed Indicator
ASR Airport Surveillance Radar 
ASRS Aviation Safety Reporting System (aviation incident reporting system run by NASA for FAA)
AT At (an altitude) 
A/T Autothrottle
ATA Air Transport Association
ATA Actual Time of Arrival
ATC Air Traffic Control (a generic term for a joint civil/military system for controlling traffic within a specific area)
ATCS Advanced Train Control Systems 
ATCSCC Air Traffic Control System Command Center
ATHR Autothrust System
ATIS Automatic Terminal Information Service (recorded voice message that provides weather and airport services information)
ATM Air Transportation Management 
ATN Aeronautical Telecommunications Network (the collection of ground subnetworks, air/ground subnetworks and airborne subnetworks interconnected by ATN routers that support computer-to-computer, internetwork communication and message transfer between host computers using the OSI ISO protocol architecture)
ATS Automatic Throttle System
ATSC Air Traffic Service Communications (Communications related to air traffic services. This includes ATC, aeronautical and meteorological information, position reporting and services related to safety and regularity of flight)
AUG August
AV Avianca 
AVAIL Available
AVHRR Advanced Very High-Resolution Radiometer
AWACS Airborne Warning And Control System 
AWAS Automated Weather Advisory Station 
AWIPS Advanced Weather Interactive Processing System 
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- B -
 
B At or Below (constrained altitude) 
BALPA British Air Line Pilots Association 
BASIS British Airways Safety Information System 
BF MarkAir 
BIT(E) Built-ln-Test (Equipment) 
BRG Bearing 
BRT Brightness 
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- C -
 
C Centigrade 
CAA Civil Aviation Authority (Great Britain) 
CAB Civil Aeronautics Board 
CAAC Civil Aviation Authority of China 
CAS Calibrated (Computed) Air Speed 
CASE Computer Aided Software Engineering 
CAT Clear Air Turbulence 
CAT Computer Aided Testing
CAT I Facility providing operation down to 200 feet decision height and runway visual range not less than 2600 feet.
CAT II Facility providing operation down to 100 feet decision height and runway visual range not less than 1200 feet.
CAT II a Facility providing operation with no decision height limit to and along the surface of the runway with external visual reference during final phase of landing and with a runway visual range not less than 700 feet.
CBT Computer Based Training 
CDI Course Deviation Indicator 
CDU Control display unit (pilots' interface to the FMS) 
CDTI Cockpit Display of Traffic Information 
CENA Centred' Études de la Navigation Aérienne (France) 
CFIT Controlled Flight Into Terrain 
CG Center of Gravity 
CGS Centimeter-gram-second 
Cl Cost Index 
CI China Airlines 
CIT Compressor Inlet Temperature 
CLB Climb Detent of the Thrust Levers 
CLR Clear 
CMC Central Maintenance Computer 
CNS Communications Navigations and Surveillance 
CO Continetnal 
COM Cockpit Operating Manual 
CON Continuous 
CO ROUTE Company Route (also CO RTE) 
COTR Contracting Officer's Technical Representative 
COTS Commercial Off The Shelf 
CP Control Panel 
CPCS Cabin Pressure Control System 
CPDLC Controller Pilot Datalink Communications 
CPU Central Processing Unit 
CRC Cyclic Redundancy Check 
CRITTER Civil Rotorcraft IFR Terminal-Area Technology Enhancement Research 
CRM Cockpit Resource Management 
CRM Crew Research Management 
CRS Course 
CRT Cathode Ray Tube 
CRZ Cruise 
CSD Constant Speed Drive 
CTA Controlled-Time of Arrival 
CTA Control Area (ICAO Term) 
CTAS Center TRACON Automation System 
CTC Centralized Train Central 
CTR Center 
CTR Civil Tilt Rotor 
CTRL Control 
CVSRF Crew-Vehicle Simulation Research Facility (NASA Ames) 
CWS Control Wheel Steering 
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- D -
 
D Derated 
DA Descent Advisor 
DBS Direct Broadcast Satellite 
DE-TO PR Derated Takeoff Engine Pressure Ratio 
D-TO Nl Derated Takeoff Engine Fan Speed 
DADC Digital Air Data Computer 
DATALINK Digitized Information Transfer (air/ground) 
DC Direct Current Electricity 
D/D Drift Down 
DEC December 
DEC Digital Equipment Corporation 
DECR Decrement 
DEL Delete 
DEP Departure 
DES Descent 
DEST Destination 
DEV Deviation 
DFDAU Digital Flight Data Acquisition Unit 
DFDR Digital Flight Data Recorder 
DFGS/C Digital Flight Guidance System/Computer 
DFW Dallas Fort Worth International Airport 
DGPS Differential GPS 
DH Decision Height 
DIR Direct 
DIR/INTC Direct Intercept 
DIS Distance 
DISCR Discrepancy 
DIST Distance 
DL Delta 
DLP Data Link Processor (the FAA's ground automation system that supports the Mode S subnetwork (GDLP), internetwork (ATN router) and non-ATC data link application processes) 
DLR German Aerospace Research Establishment 
DME Distance Measuring Equipment (ground navigational aid that can provide display of distance to selected ground navigational radio transmitter) 
DMU Data Management Unit 
DNTKFX DownTrack Fix 
DOT Department of Transportation 
DOD Department of Defense 
DRU Data Retrival Unit 
DSPY Display (annunciation on CDU) 
DTG Distance-to-go 
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- E -
 
E East 
EADI Electronic Attitude Director Indicator 
EAS Equivalent Airspeed 
ECAM Electronic Centralized Aircraft Monitor 
ECON Economy (minimum cost speed schedule) 
ECS Environmental Control System 
E/D End-of-Descent 
EDF Electricité de France 
EEC Electronic Engine Control 
EFC Expected Further Clearance 
EFIS Electronic Flight Instrument System 
EGT Exhaust Gas Temperature 
EHSI Electronic Horizontal Situation Indicator 
EICAS Engine Indicating Crew Alerting System 
EIU Electronic Interface Unit 
ELT Emergency Locator Transmitter 
EMP Electromagnetic Pulse 
EMS Emergency Medical Services 
ENG Engine 
E/O Engine-Out 
EPR Engine Pressure Ratio 
EPROM Erasable Programmable Read-Only Memory 
EST Estimated 
ETA EstimatedTime of Arrival 
ETX End of Transmission 
EXEC Execute 
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- F -
 
F Fahrenheit 
FA Final Approach 
FAA Federal Aviation Administration 
FADEC Full Authority Digital Engine Control 
FAIL FMC Fail 
Failure The inability of a system, subsytem, unit or part to perform within previously specified limits. 
FAF Final Approach Fix 
FANS Future Air Navigation Systems 
FAR Federal Aviation Regulations (federal rules under which flight operations are conducted) 
FAR Federal Acquisition Regulation 
FAST Final Approach Spacing Tool 
FBO Fixed Based Operator 
FCC Flight Control Computer 
FCU Flight Control Unit 
F/D (FD) Flight Director 
FDAMS Flight Data Acquisition and Management System 
FDC Flight Data Company 
FDR Flight Data Recorder 
FEATS Future European Air Traffic System 
FEB February 
FF Fuel Flow 
FGS/C Flight Guidance System/Computer 
FIR Flight Information Region 
Fix Position in space usually on aircraft's flight plan 
FL Flight Level 
FL 310 For example, FL310 is an altitude 31,000 ft. above sea level; used for altitudes above 18,000 ft 
FLCH Flight Level Change 
FLIDRAS Flight Data Replay and Analysis System 
FLT Flight 
FMA Flight Mode Annunciator: display on or near the PFDs of the current modes of autoflight system 
FMC Flight Management Computer (also FMCS - FMC System) 
FMGC Flight Management Guidance Computer 
FMGS Flight Management Guidance System 
FMS Flight Management System 
FO First officer 
FOQA Flight Operations Quality Assurance 
FPA Flight Path Angle 
FPA Focal Plane Array 
FPM Feet Per Minute 
FQIS Fuel Quantity Indicating System 
FR From 
FRA Flap Retraction Altitude 
FRA Federal Railroad Administration 
FREQ Frequency 
FSF Flight Safety Foundation 
FT Feet 
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- G -
 
GA Go-Around 
GA General Aviation 
GAR Go-Around 
GCA Ground-controlled Approach 
GDLP Ground Data Link Processor (the Mode S subnetwork function within the ground system that implements the OSI network layer protocols) 
GHz Gigahertz 
GMT Greenwich MeanTime 
GNSS Global Navigation Satellite System 
GPS Global Positioning System 
GPWS Ground Proximity Warning System (warns of inadequate separation from ground and excessive sink rate close to ground) 
GRAF Ground Replay and Analysis Facility 
GRP Geographical Reference Points 
GS Glide Slope 
GS Ground Speed 
G/S Glideslope 
GSFC Goddard Space Flight Center 
GW Gross Weight 
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- H -
 
HAC Hughes Aircraft Co. 
HAI Helicopter Association International 
HBARO Barometric Altitude 
HDG Heading 
HDG SEL Heading Select 
HDOT Inertial Vertical Speed 
HE Altitude Error 
HF High Frequency 
Hl High 
HIRS High-Resolution Infrared Sounder 
Host Computer Facility located at the ARTCC which operates user application software, as well as certain peer network layer protocols required to communicate with adjacent ATN routers. 
Host Processor "End system" as defined by ISO that includes the OSI upper layer protocols (i.e., transport layer and above) and application processes 
HP Holding Pattern 
HPRES Pressure Altitude 
HSI Horizontal Situation Indicator 
HUD Head-Up Display 
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- I -
 
IA Inspection Authorization 
IAOA Indicated Angle-of-Attack 
IAS Indicated Airspeed 
ICAAS Integrated Control in Avionics for Air Superiority 
ICAO International Civil Aviation Organization 
ID Identifier 
IDENT Identification 
IEPR Integrated Engine Pressure Ratio 
IF Intermediate Frequency 
IFR Instrument Flight Rules 
IFRB International Frequency Registration Board 
IGFET Insulated Gate Field Effect Transistor 
ILS Instrument Landing System (uses precision localizer and glide-slope radio transmitters near a runway to provide landing approach guidance) 
IMC Instrument Meteorological Conditions 
INBD Inbound 
INFO Information 
in.hg. inches of mercury 
INIT Initialization 
INR Image Navigation and Registration 
INS Inertial Navigation System 
INTC Intercept 
IPT Integrated Product Team 
IRS Inertial Reference System 
IRU Inertial Reference Unit 
ISA International Standard Atmosphere 
ISO International Standards Organization 
ITU International Telecommunications Union 
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- J -
 
JAL Japan Air Lines 
JAN January 
JAR Joint Airworthiness Regulations 
JATO Jet Assisted Takeoff 
JL Japan Air Lines 
JSRA Joint Sponsored Research Agreement 
JUL July 
JUN June 
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- K -
 
KG Kilogram 
kHz kilohertz 
KLM Royal Dutch Airlines 
km Kilometer 
KT (kts) Knots 
kW Kilowatt 
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- L -
 
L Left 
LAT Latitude 
LAX Identifier for Los Angeles 
LCN Local Communications Network. 
LDGPS Local DGPS 
LFR Low-frequency Radio Range 
LIM Limit 
LMM Compass locator at the middle marker 
LNAV Lateral Navigation (provides computer description of aircraft's planned lateral flight path that can be tracked by the autoflight system; lateral path can be shown on map display.) 
LO Low 
LOC Localizer Beam 
LOE Line Oriented Evaluation 
LOFT Line Oriented Flight Training 
LOM Compass Locator at the Outer Marker 
LON Longitude 
LORAN Long Range Navigation 
LOS Line-Oriented Simulation 
LRC Long Range Cruise 
LRU Line Replaceable Unit 
LVL CHG Level Change 
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- M -
 
M Mach Number 
M Manual Tuned NAVAID 
MAA Maximum Authorized IFR Altitude 
MAG Magnetic 
MAINT Maintenance 
MAN Manual 
MAP Missed Approach 
MAR March 
M/ASI Mach/Airspeed Indicator 
MAX Maximum 
MAX CLB Maximum engine thrust for two-engine climb 
MAX CRZ Maximum engine thrust for two-engine cruise 
MCA Minimum Crossing Altitude 
MCDU Multipurpose Control Display Unit 
MCP Mode Control Panel (pilots' interface to the autoflight system; usually located centrally just below cockpit glare shield) 
MCT Maximum Continuous Thrust 
MCW Modulated Continuous Wave 
MDA McDonnell-Douglas Aerospace 
MDA Minimum Descent Altitude 
MDL Multipurpose Data Link 
MEA Minimum Enroute Altitude 
MEL Minimum Equipment List 
MIDAS Man-Machine Integration Design and Analysis System (NASA Ames) 
MIDAS Multi-discipline Data Analysis System 
MILSPEC Military Specifications 
MIN Minutes 
MIN Minimum 
MIT Massachusetts Institute of Technology 
MLA ManeuverLimited Altitude 
MLE Landing Gear Extended Placard Mach Number 
MLS Microwave Landing System 
MMO Mach Max Operating 
MN Magnetic North 
MOA Memorandum of Agreement 
MOCA Minimum Obstruction Clearance Altitude 
MOD Modified/Modification 
Mode S Type of secondary surveillance radar (SSR) equipment which provides Mode A and Mode C interrogations, discrete address (Mode S) interrogations from the ground or air, and a data link capability 
MODIS Moderate-resolution Imaging Spectrometer 
MRA Minimum Reception Altitude 
MSG Message 
MSL Mean Sea Level 
MTBF Mean Time Between Failures 
MU Management Unit 
MWP Meteorological Weather Processor 
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- N -
 
N North 
NACA National Advisory Committee for Aeronautics 
NADIN II National Airspace Data Interchange Network II (the national digital message switching network for aeronautical data) 
NAS National Airspace System 
NAS National Aircraft Standard 
NASA National Aeronautics and Space Administration 
N/A Not Applicable 
NATCA National Air Traffic Controllers Association 
NAV Navigation 
NAVAID Navigational Aid 
NBAA National Business Aircraft Association 
NGATM New Generation Air Traffic Manager 
ND Navigation Display 
NDB Nondirectional Radio Beacon 
NESDIS National Environmental Satellite, Data, and Information Service 
NLM Network Loadable Module 
NLR National Research Laboratory (The Netherlands) 
NM Nautical Mile 
NMC National Meteorological Center 
NOAA National Oceanic and Atmospheric Administration 
NOTAM Notice for Airman 
NOV November 
NRP National Route Program 
NTSB National Transportation Safety Board 
NW Northwest Airlines 
NWS National Weather Service 
Nl Engine Revolutions per Minute (percent) 
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- O -
 
OAG Official Airline Guide 
OAT Outside AirTemperature 
OATS Orbit and Attitude Tracking 
OBTEX Offboard Targeting Experiments 
OCT October 
ODAPS Operational OGE Data Acquisition and Patch Subsystem 
OFST Lateral Offset Active Light 
OGE Operational Ground Equipment 
OIS OGE Input Simulator 
OO SkyWest Airlines 
OP Operational 
OPT Optimum 
O-QAR Optical Quick Access Recorder 
OSI Open Sytem Interconnection (ISO defined communications architecture used in data link to permit heterogeneous data communication systems to be interconnected in order to allow the reliable exchange of messages without regard to the implementation of the networks and physical media through which the messages pass) 
OTFP Operational Traffic Flow Planning 
OV Overseas National Airways 
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- P -
 
P Procedure-Required Tuned NAVAID 
PA Pan Am 
PAR Precision Approach Radar 
PAWES Performance Assessment and Workload Evaluation 
PBD Place Bearing/Distance (way point) 
PD Profile Descent 
PDB Performance Data Base 
PDC Pre Departure Clearance 
PERF Performance 
PF Pilot Flying 
PFD Primary Flight Display 
PHARE Program for Harmonized ATC Research in Europe 
PHIBUF Performance Buffet Limit 
PHINOM Nominal Bank Angle 
PIREPS Pilot Reports 
PMS Performance Management System 
PND Primary Navigation Display 
PNF Pilot Not Flying 
POS Position 
POS INIT Position Initialization 
POS REF Position Reference 
PPI Plan Position Indicator 
PPOS Present Position 
PREV Previous 
PROC Procedure 
PROF Profile 
PROG Progress Page on MCDU 
PROV Provisional 
PS Pacific Southwest Airways 
PT Total Pressure 
PTH Path 
PVD Plan View Display 
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- Q -
 
QAR Quick Access Recorder 
QRH The barometric pressure as reported by a particular station 
QTY Quantity 
QUAD Quadrant 
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- R -
 
R Right 
R Route Tuned NAVAID 
RAD Radial 
RAD Radio 
RAPS Recovery Access Presentation System 
RASCAL Rotorcraft Air Crew Systems Concepts Airborne Laboratory 
RCP Radio Control Panel 
R/C Rate of Climb 
RDP Radar Data Processing (system) 
REF Reference 
REQ Required/Requirement 
REQ Request 
RESTR Restriction 
RESYNCING Resynchronizing 
rf radio frequency 
RMPs Radio Management Panels 
RNAV Area Navigation (generic acronym for any device capable of aircraft guidance between pilot-defined waypoints 
RNP Required Navigation Performance 
Router An ATN network layer gateway which performs the relaying and routing of data packets across interconnecting subnetworks based on the source and destination network layer addresses and the desired quality of network service 
RTA Required Time of Arrival 
RTCA Radio Technical Committee on Aeronautics 
RTE Route 
RVR Runway Visual Range 
RW Runway 
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- S -
 
S South 
SA Situation Awareness 
SAS Scandinavian Airlines System 
SAT Static Air Temperature 
SATCOM Satellite Communications 
SBIR Small Business Innovative Research 
S/C Step Climb 
SEA/TAC Seattle/Tacoma International Airport 
SEL Selected 
SEP September 
SESMA Special Event Search and Master Analysis 
SID Standard Instrument Departure 
SIGMET Significant Meteorological Information 
SITA Société Internationale Télécommunique Aéronautique 
SO Southern Airways 
SOP Standard Operating Procedure 
SOPA Standard Operating Procedure Amplified 
SP Space 
SPD Speed Mode 
SPS Sensor Processing Subsystem 
SQL Structured Query Language 
SRP Selected Reference Point 
SSFDR Solid-State Flight Data Recorder 
SSM Sign Status Matrix 
STAB Stabilizer 
STAR StandardTerminal Arrival Route 
STEPCLB StepClimb 
STOL Short Takeoff and Landing 
STTR Small Business Technology Transfer Resources 
SUA Special Use Airspace 
SWAP Severe Weather Avoidance Program 
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- T -
 
TACAN Tactical Air Navigation 
TACH Tachometer 
TAI Thermal Anti-lce 
TAP Terminal Area Productivity 
TAS True Airspeed 
TAT Total AirTemperature 
TATCA Terminal Air Traffic Control Automaiton 
TBD To Be Determined 
TBO Time between Overhauls 
TBS To Be Specified 
TCA Terminal Control Area 
TCAS Traffic Alert & Collision Avoidance System 
T/C (TOC) Top-of-Climb 
T/D (TOD) Top of-Descent 
TDWR Terminal Doppler Weather Radar (TDWR located and classifies windshear conditions and provides advisories in the terminal area. These data are available through the DLP.) 
TEMP Temperature 
TFM Traffic Flow Management 
TGT Target 
THDG True Heading 
THR Thrust 
THR HOLD Throttle Hold 
TI Texas International 
TIAS True Indicated Airspeed 
TKE TrackAngle Error 
TMA Traffic Management Advisor 
TMC Thrust Management Computer 
TMF Thrust Management Function 
TMU Traffic Management Unit 
TN True North 
T/O (TO) Takeoff 
TOD Top of Descent 
TO EPR Takeoff Engine Pressure Ratio 
TO Nl Takeoff Engine Fan Speed 
TOGA Takeoff/Go-Around 
TOT Total 
TRA Thrust Reduction Altitude 
TRACON Terminal Radar Approach Control Facility. 
TRANS Transition 
TRK Track (to a NAVAID) 
TRU True 
TSRV Transport Systems Research Facility 
TT Total Temperature 
TURB Turbulence 
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- U -
 
UA United 
UHF Ultra-high Frequency 
US USAir 
USAF United States Air Force 
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- V -
 
V Velocity 
VA Heading to an Altitude 
VA Design Maneuvering Speed 
VAR Variation 
VAR Volt-amps Reactive 
VAR Visual-aural Radio Range 
VASI Visual Approach Slope Indicator 
VBF(LO) Flaps up minimum buffet speed at current maneuver load factor minus altitude dependent variable 
VBFNG(HI) High speed CAS at N g's to buffet onset 
VBFNG(LO) Low speed CAS at N g's to buffet onset 
VCMAX Active Maximum Control Speed 
VCMIN Active Minimum Control Speed 
VC Design Cruising Speed 
VD Design Diving Speed 
VD Heading to a DME distance 
VF Design Flap Speed 
VFE Flaps Extended Placard Speed 
VFR Visual Flight Rules 
VFXR(R) Flap Retraction Speed 
VFXR(X) Flap Extension Speed 
VG Ground Velocity 
VGND Ground Velocity 
VH Maximum Level-flight Speed with Continuous Power 
VHF Very-high Frequency 
VHRR Very High-Resolution Radiometer 
VISSR Visible Infrared Spin Scan Radiometer 
Vl Heading to a course intercept 
Vls Lowest Selectable Airspeed 
VLE Landing Gear Extended Placard Airspeed 
VLO Maximum Landing Gear of Operating Speed 
VLOF Lift-off Speed 
VM Heading to a manual termination 
VMC Visual Meteorological Conditions 
VMC Minimum Control Speed with Critical Engine Out 
VM(LO) Minimum Maneuver Speed 
VMAX Basic Clean Aircraft Maximum CAS 
VMIN Basic Clean Aircraft Minimum CAS 
VMO Velocity Max Operating 
VNAV Vertical Navigation (provides computer description of aircraft's speed and altitude that can be tracked by autoflight system) 
VNE Never-exceed Speed 
VNO Maximum Structural Cruising Speed 
VOM Volt-ohm-milliammeter 
VOR VHF OmniRange Navigatgion System (ground navigational aid that can provide display of aircraft position relative to course through selected ground navigational radio transmitter) 
VORTAC VHF Omni Range Radio/Tactical Air Navagation 
VPATH Vertical Path 
VR Heading to a radial 
VR Takeoff Rotation Velocity 
VREF Reference Velocity 
VS Design Speed for Maximum Gust Intensity 
V/S Vertical Speed/Vertical 
VSCS Voice Switching and Control System 
VSI Stalling Speed in a Specified Flight Configuration 
VSO Stalling Speed in the Landing Configuration 
VSTOL Vertical or Short Takeoff and Landing 
VTK Vertical Track Distance 
VTOL Vertical Takeoff and Landing 
V/TRK Vertical Track 
VTR Variable Takeoff Rating 
VU Utility Speed 
VX Speed for Best Angle of Climb 
VY Speed for Best Rate of Climb 
Vl Critical Engine Failure Velocity (Takeoff Decision Speed) 
V2 Takeoff Climb Velocity 
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- W -
 
W West 
WAAS Wide Area Augmentation System 
Waypoint Position in space usually on aircraft's flight plan 
WBC Weight and Balance Computer 
WINDR Wind Direction 
WINDMG Wind Magnitude 
WPT Way point 
W/MOD With Modification of Vertical Profile 
WMSC Weather Message Switching Center 
WMSCR Weather Message Switching Center Replacement 
WO World Airways 
W/STEP With Step Change in Altitude 
WT Weight 
WX Weather 
WXR Weather Radar 
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- X -
X-BAND The frequency range between 8000 and 12500 MHz
XCVR Transceiver 
XFR Transfer 
XLTR Translater 
XM External Master 
XMIT Transmit 
XMITR Transmitter 
XPD ATC Transponder (also XPDR, XPNDR, TPR) 
XTK Crosstrack (cross track error) 
XY Ryan Air 
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- Y -
YSAS Yaw Stability Augmentation System 
  
YD Yaw Damper 
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- Z -
 
Z Zulu (GMTtime) 
ZFW Zero Fuel Weight 
ZNY New York Air Route Traffic Control Center 
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Revised: .
All trademarks or product names mentioned herein are the property of their respective