Common Avionics Acronyms


: Amps.

ACARS: Aircraft Communications Addressing and Reporting System.

ACAS: Airborne Collision Avoidance System.

ACP: Audio Control Panel.

ACS: Audio Control System.

A/D: Analog to Digital.

ADAHRS: Air Data and Attitude Heading Reference System.

ADC: Air Data Computer.

ADF: Automatic Direction Finder.

ADI: Attitude Director Indicator.

ADIRS: Air Data Inertial Reference System.

ADIRU: Air Data Inertial Reference Unit.

ADM: Air Data Module.

ADS: Either; Automatic Dependant Surveillance or Air Data System.

ADS-A: Automatic Dependant Surveillance /Address.

ADS-B: Automatic Dependant Surveillance/Broadcast.

ADSEL: Address Selective.

ADSP: Automatic Dependant Surveillance Panel.

AET: Aircraft Electronics Technician (A NCATT certified technician).

AFCS: Automatic Flight Control System.

AFD: Autopilot Flight Director.

AFDC: Autopilot Flight Director Computer.

AFDS: Autopilot Flight Director System.

AFIS: Either; Automatic Flight Information Service or Airborne Flight Information System.

AGACS: Automatic Ground-Air Communications System, is also known as ATCSS or data link.

AGC: Automatic Gain Control.

AHC: Attitude Heading Control.

AHRS: Attitude Heading Reference System.

Air Data: Various parameters that can be derived from knowledge of the air mass surrounding the aircraft.

ALC: Automatic Level Control.

ALT: Either; Altimeter or Altitude.

ALT Hold: Altitude Hold Mode.

ALTS: Altitude Select.

AMLCD: Active Matrix Liquid Crystal Display.

ANC: Active Noise Cancellation.

ANN: Annunciator- caution warning system normally containing visual and audio alerts to the pilot.

ANR: Active Noise Reduction.

ANT: Antenna.

A/P: Autopilot.

APC: Autopilot Computer.

APS: Autopilot System.

ASD: Aircraft Situation Display.

ASDL: Aeronautical Satellite Data Link.

ASR: Airport Surveillance Radar.

ASU: Avionics Switching Unit.

ATCRBS: Air Traffic Control Radar Beacon System.

ATCSS: Air Traffic Control Signaling System.

ATI: Unit of measure for instrument size, a standard 3ยจรป cutout is a 3ATI.

ATT: Attitude.

Avionics: Aviation electronics.

AWG: American Wire Gauge.


B RNAV: Basic Area Navigation.

BARO: Barometric indication, setting or pressure.

BCRS: Back Course.

BDI: Bearing Distance Indicator.

BGAN: Broadcast Global Area Network.


CAI: Caution Annunciator Indicator.

CAT I: Operational performance Category 1.

CAT I Enhanced. Allows for lower minimums than CAT I in some cases to CAT 2 minimums.

CAT II: Operational performance Category II.

CAT IIIa: Operational performance Category IIIa.

CAT IIIb: Operational performance Category IIIb.

CAT IIIc: Operational performance Category IIIc.

CODEC: Coder/Decoder.

CDI: Course Deviation Indicator.

CFIT: Controlled Flight Into Terrain.

COMM or COM: Communications Receiver.

CNS: Communication, Navigation, Surveillance.

CNS/ATM: Communication, Navigation, Surveillance/Air Traffic Management.

CPDLC: Controller-Pilot Data Link Communication.

CPS: Cycles Per Second.

CRT: Cathode Ray Tube.

CTAF: Common Traffic Advisory Frequency.

CV/DFDR: Cockpit Voice and Digital Flight Recorder.

CVR: Cockpit Voice Recorder.

CWS: Control Wheel Steering.


DA: Drift Angle.

DG: Directional Gyroscope.

DGPS: Differential Global Positioning System.

DH: Decision Height.

DME: Distance Measuring Equipment.

DNC: Direct Noise Canceling.

DP: Departure Procedures.

DSP: Digital Signal Processing.

DUAT: Direct User Access Terminal.


EADI: Electronic Attitude Director Indicator.

EFD: Electronic Flight Display.

EFIS: Electronic Flight Instrument System.

EGPWS: Enhanced Ground Proximity Warning System.

EGT: Exhaust Gas Temperature.

EHSI: Electronic Horizontal Situation Indicator.

EICAS: Engine Indication Crew Alerting System.

ELT: Emergency Locator Transmitter.

ENC: Electronic Noise Canceling.

ENR: Electronic Noise Reduction.

EPR: Engine Pressure Ratio.


FADEC: Full Authority Digital Engine Control.

FAT: Free Air Temperature.

FDRS: Flight Data Recorder System.

FDU: Flux Detector Unit.

FF: Fuel Flow.

FIS-B: Flight Information Services- Broadcast.

FLIR: Forward Looking Infra-Red.

FLTA: Forward Looking Terrain Avoidance.

FMS: Flight Management System.

FREQ: Frequency.

FYDS: Flight director/ Yaw Damper System.


GCAS: Ground Collision Avoidance System.

GCU: Generator Control Unit.

GDOP: Geometric Dilution Of Precision.

GGS: Global positioning system Ground Station.

GHz: Gigahertz.

GLNS: GPS Landing and Navigation System.

GLNU: GPS Landing and Navigation Unit.

GLONASS: Global Navigation Satellite System.

GLS: GPS Landing System.

GLU: GPS Landing Unit.

GND: Ground.

GNSS: Global Navigation Satellite System.

GMT: Greenwich Mean Time.

GPS: Global Positioning Satellite or Global Positioning System.

GPWC: Ground Proximity Warning Computer.

GPWS: Ground Proximity Warning System.


HDG: Heading.

HDG SEL: Heading Select.

HDOP: Horizontal Dilution Of Precision.

HF: High Frequency.

HHLD: Heading Hold.

HSD: High Speed Data.

HSI: Horizontal Situation Indicator.

HSL: Heading Select.

HUD: Head-Up Display.

Hz: Hertz.


IAS: Indicated Airspeed.

ID: Identify/Identification or identifier.

IDENT: Identify/Identifier.

IDS: Information Display System or Integrated Display System.

IFE: In-Flight Entertainment.

IFR: Instrument Flight Regulations.

ILS: Instrument Landing System.

IMC: Instrument Meteorological Conditions.

InHg: Inches of Mercury.

IND: Indicator.

ISA: International Standard Atmosphere.

ISP: Integrated Switching Panel.

ITT: Interstage Turbine Temperature.

IVSI: Instantaneous Vertical Speed Indicator.



kHz: Kilohertz.


LAAS: Local Area Augmentation System.

LADGPS: Local Area Differential GPS.

LCD: Liquid Crystal Display.

LDGPS: Local area Differential Global Positioning Satellite.

LED: Light Emitting Diode.

LMM: Locator Middle Marker.

LOC: Localizer.

LOM: Locator Outer Marker.

LRU: Line Replaceable Unit


MAP: Manifold Absolute Pressure or Missed Approach Point.

MB: Marker Beacon.

MCBF: Mean Cycles Between Failures.

MDA: Minimum Decent Altitude.

MEL: Minimum Equipment List.

MF: Medium Frequency.

MFD: Multi-Function Display.

MFDS: Multi-Function Display System.

MHz: Megahertz.

MIC: Microphone.

MILSPEC: Military Specification.

MKR: Marker Beacon or Marker.

MLS: Microwave Landing System.

MMD: Moving Map Display.

MOA: Military Operations Area.

Mode A: Transponder pulse code reporting.

Mode C: Transponder code and altitude reporting.

Mode S: Transponder code, altitude, and TCAS reporting.

MSG: Message.

MSP: Modes S Specific Protocol.

MSSS: Mode S Specific Services.

MTBF: Mean Time Between Failures.

MTTF: Mean Time To Failure.


NAS: National Airspace System.

NAV: Navigation receiver.

Navaid: Navigational Aid.

NAVCOMM: Navigation and Communications equipment or receiver.

NAVSTAR-GPS: The formal name for the space-borne or satellite navigation system.

NCATT: National Center for Aircraft Technician Training.

ND: Navigation Display.

NDB: Non-Directional radio Beacon.

NFF: No Fault Found.

NM or NMI: Nautical Mile.

NPA: Non-Precision Approach.


OAT: Outside Air Temperature.

OBS: OmniBearing Selector.

OM: Outer Marker.


P-Code: GPS precision code.

PAPI: Precision Approach Path Indicators.

PAR: Precision Approach Radar.

PD: Profile Descent.

PDOP: Position Dilution Of Precision.

PFD: Primary Flight Display or Primary Flight Director.

PMG: Permanent Magnet Generator:

PND: Primary Navigation Display.

PNR: Passive Noise Reduction.

POS: Position.

PSR: Primary Surveillance Radar.

PTT: Push To Talk.



RAI: Radio Altimeter Indicator.

RAIM: Receiver Autonomous Integrity Monitoring.

RALT: Radar or Radio Altimeter.

RCR: Reverse Current Relay.

RCVR: Receiver.

RDMI: Radio Distance Magnetic Indicator.

RDP: Radar Data Processing system.

RDR: Radar.

REF: Reference.

REL: Relative.

RF: Radio Frequency.

RFI: Radio Frequency Interference.

RHSM: Reduced Horizontal Separation Minimal.

RLG: Ring Laser Gyroscope.

RLY: Relay.

RMI: Radio Magnetic Indicator.

R-NAV: Area Navigation.

RNG: Range.

RNP: Required Navigation Performance.

ROC: Rate Of Climb.

ROD: Rate Of Descent.

RPM: Revolutions Per Minute.

RTE: Route.

RVR: Runway Visual Range.

RVSM: Reduced Vertical Separation Minimum.

RX: Receiver.


SAT: Static Air Temperature.

SATCOM: Satellite Communication.

SATNAV: Satellite Navigation.

SD: Secure Digital.

SID: Standard Instrument Departure.

SIU: Satellite Interface Unit.

SL: Sensitivity Level.

SMS: Short Messaging Service.

SNR: Signal to Noise Ratio.

SPKR: Speaker.

SQ or SQL: Squelch.

SSCV/DR: Solid State Cockpit Voice/Data Recorder.

SSCVR: Solid State Cockpit Voice Recorder.

SSFDR: Solid State Flight Data Recorder.

SSR: Secondary Surveillance Radar.

STAR: Standard Terminal Arrival Route.

STARS: Standard Terminal Automation Replacement System.

STC: Supplemental Type Certificate.

STP: Standard Temperature and Pressure.

SUA: Special Use Airspace.


TA: Traffic Advisory (TCAS).

TACAN: Tactical Air Navigation system.

Tach: Tachometer.

TAD: Terrain Awareness Display.

TAF: Terminal Area Forecast.

TAS: True Airspeed.

TAT: True Air Temperature or Total Air Temperature.

TAWS: Terrain Awareness Warning System.

TBO: Time Before Overhaul or Time Between Overhaul.

TCA: Throttle Control Assembly or Terminal Control Area.

TCAS: Traffic Collision Alert and avoidance System.

TCF: Terrain Clearance Floor.


TCU: TACAN Control Unit.

TDOP: Time Dilution Of Precision.

TDR: Transponder (in some cases).

TERPS: Terminal Instrument Procedures or Terminal EnRoute Procedures.

TFR: Temporary Flight Restrictions.

TFT: Thin Film Transistor.

TGT: Turbine Gas Temperature or Target.

THDG: True Heading.

TIAS: True Indicated Airspeed.

TIS: Traffic Information Service.

TK: Track Angle.

TKE: Track Angle Error.

TOT: Turbine Outlet Temperature.

TR or T/R: Transmitter Receiver or transceiver.

TRACON: Terminal Radar Approach Control.

TRANS: Transmit, Transmission, or Transition.

TRK: Track.

TRP: Mode S Transponder.

TTR: TCAS II Transmitter/Receiver.

TTS: Time to Station.

TVE: Total Vertical Error.

TWDL: Two-Way Data Link, or Terminal Weather Data Link.

TWDR: Terminal Doppler Weather Radar.

TWIP: Terminal Weather Information for Pilots.

TWR: Terminal Weather Radar.

TX: Transmit.


UART: Universal Asynchronous Receiver Transmitter.

UHF: Ultra-High Frequency.

ULB: Underwater Locator Beacon.

USB: Universal Serial Bus.

UTC: Universal Time Coordinate.


V: Volts or voltage.

VASI: Visual Approach Slope Indicator.

VDL: VHF Data Link.

VDR: VHF Digital Radio.

VFO: Variable Frequency Oscillator.

VFR: Visual Flight Regulations.

VG/DG: Vertical Gyroscope/Directional Gyroscope.

VGA: Video Graphics Array.

VHF: Very High Frequency.

V/L: VOR/Localizer.

VMC: Visual Meteorological Conditions or minimum control speed with critical engine out.

V/NAV: Vertical Navigation.

VNE: never exceed speed.

VNO: maximum structural cruising speed.

VNR: VHF Navigation Receiver.

VOR: VHF Omnidirectional Radio and Ranging.

VOR/DME: VOR with Distance Measuring Equipment.

VOR/MB: VOR Marker Beacon.

VORTAC: VOR and TACAN combination.

VOX: Voice Transmission.

VPATH: Vertical Path.

V/R: Voltage Regulator.

V/REF: Reference Velocity.

V/S: Vertical Speed.

VSI: Vertical Speed Indicator.

VSM: Vertical Separation Limit.

VSO: stall speed in landing configuration.

VSWR: Voltage Standing Wave Ratio.

V/TRK: Vertical Track.

VX: speed for best angle of climb.

VY: speed for best rate of climb.


WAAS: Wide Area Augmentation System.

WD/WINDR: Wind Direction.

WMA: WXR Waveguide Adapter.

WMI: WXR Indicator Mount.

WMS: Wide area Master Station.

WMSC: Weather Message Switching Center.

WMSCR: Weather Message Switching Center Replacement.

WPT: Waypoint.

WRT: WXR Receiver Transmitter.

WX: Weather.

WXR: Weather Radar System.

WYPT: Waypoint.


XCVR: Transceiver.

XFR: Transfer.

XMIT: Transmit.

XMSN: Transmission.

XMTR: Transmitter.

XPDR: Transponder.

XTK: crosstrack.


YD: Yaw Damper.