Acronyms and abbreviations in avionics

A

• A/A: Air to air TACAN function
• A/P: Autopilot
• AAIM: Aircraft Autonomous Integrity Monitoring
• ABAS: Aircraft-based augmentation system
• AC: Advisory Circular
• ACARS: Aircraft communications addressing and reporting system
• ACAS: Airborne collision avoidance system
• ACC: Area control centre
• ACE: Actuator control electronics
• ACMS: Aircraft condition monitoring system
• ACP: Audio control panel
• ACR: Avionic Communication Router
• ACS: Audio control system
• 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 dependent surveillance or air data system
• ADS-A: Automatic dependent surveillance – address
• ADS-B: Automatic dependent surveillance – broadcast
• ADS-C: Automatic dependent surveillance – contract
• AESA: Active electronically scanned array
• AFCS: Automatic flight control system
• AFD: Autopilot flight director
• AFDC: Autopilot flight director computer
• AFDS: Autopilot flight director system
• AFDX: Avionics Full-Duplex Switched Ethernet
• 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
• AGDL: Air–ground data link
• AGL: Above Ground Level
• AHC: Attitude heading control
• AHRS: Attitude and heading reference system
• AHRU: Attitude and heading reference unit
• AIDS: Aircraft integrated data system
• AIP: Aeronautical Information Publication
• AIRAC: Aeronautical Information Regulation & Control
• AIXM: Aeronautical information exchange model
• ALC: Automatic level control
• ALT: Either; altimeter or altitude
• ALT hold: Altitude hold mode
• ALTS: Altitude select
• AMLCD: Active-matrix liquid crystal display
• AMO: Approved maintenance organisation
• AMS: Air management system
• ANC: Active noise cancellation
• ANN: Annunciator – caution warning system normally containing visual and audio alerts to the pilot
• ANR: Active noise reduction
• ANT: Antenna
• AOC: Aeronautical operational control
• AOP: Airport operating plan
• APARS: Automatic pressure altitude reporting system
• APIRS: Attitude and positioning inertial reference system
• APOA: Airport of arrival
• APC: Auto pilot computer
• APOD: Airport of departure
• APM: Aircraft personality module
• APS: Auto pilot system
• APU: Auxiliary power unit
• APV: Approach Procedure with Vertical guidance
• ARINC: Aeronautical Radio, Incorporated
• ASD: Aircraft situation display
• ASDL: Aeronautical satellite data link
• ASI: Airspeed indicator
• ASR: Airport surveillance radar
• ASU: Avionics switching unit
• AT: Auto throttle
• ATC: Air traffic control
• ATCC: Air traffic control centre
• ATCT: Airport traffic control tower
• ATCRBS: Air traffic control radar beacon system
• ATCSS: Air traffic control signalling system
• ATIS: Automated terminal information service
• ATR: Air transportable racking
• ATR: Automatic thrust restoration
• ATSAW: Airborne traffic situational awareness
• ATSU: Air traffic services unit
• ATT: Attitude
• ATTCS: Automatic Take-off Thrust Control System
• Avionics: Aviation electronics
• AWOS: Automated weather observation system
• AWACS: Advanced warning and control systems
• ALNA: Airline network architecture

  B

• B RNAV: Basic area navigation
• BARO: Barometric indication, setting or pressure
• baro-VNAV: Barometric vertical navigation
• BITE: Built-in test equipment
• BCRS: Back course
• BDI: Bearing distance indicator
• BGAN: Broadcast Global Area Network
• BER: Beyond economic repair
• BTV: Brake to Vacate

  C

• C/L: Centre line
• CAA: Civil Aviation Authority
• CACTCS: Cabin Air Conditioning and Temperature Control System
• CAI: Caution advisory panel
• CAS: Calibrated airspeed
• CAM: Cockpit area microphone
• 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
• CB: Cumulonimbus cloud
• CBT: Computer-based training
• CDA: Continuous descent approach
• CDCCL: Critical Design Configuration Control Limitations
• CDI: Course deviation indicator
• CDTI: Cockpit display of traffic information
• CFIT: Controlled flight into terrain
• CHP: Course Heading Panel
• CHT: Cylinder Head Temperature
• CMU: Communications Management Unit
• CNS: Communication, navigation and surveillance
• CNS/ATM: Communication, navigation and surveillance / Air traffic management
• CODEC: Coder/decoder
• COMM or COM: Communications transceiver, Communications receiver, or Communications radio transmitter
• COTS: Commercial off-the-shelf
• CPA: Closest point of approach
• CPDLC: Controller–pilot data link communications
• CPS: Cycles per second
• CRM: Crew Resource Management
• CRT: Cathode ray tube
• CTAF: Common traffic advisory frequency
• CV/DFDR: Cockpit voice and digital flight data recorder
• CVR: Cockpit voice recorder
• CWS: Control wheel steering

  D

• DA: Decision Altitude
• DA: Drift angle
• DAPs: Downlink of aircraft parameters
• DCDU: Data link control and display unit
• DCL: Departure Clearance via CPDLC
• DCP: Display control panel
• DFDR: Digital Flight Data Recorder
• DFMC: Dual Frequency Multiple Constellation
• DG: Directional gyroscope
• DGPS: Differential global positioning system
• DH: Decision height
• DLR: Data link recorder
• DME: Distance measuring equipment
• DNC: Direct noise canceling
• DP: Departure procedures
• DPU: Display Processor Unit
• DSP: Digital signal processing
• DTU: Data transfer unit
• DUAT: Direct user access terminal
• DVE: Degraded Visual Environment
• DRMC : Direct Reading Magnetic Compass.

  E

• EADI: Electronic attitude director indicator
• ECAM: Electronic Centralised Aircraft Monitor
• ECU: Engine Control Unit
• EEC: Electronic Engine Control
• EFD: Electronic flight display
• EFIS: Electronic flight instrument system
• EGI: Embedded GPS Inertial
• EGNOS: European Geostationary Navigation Overlay Service
• EGPWS: Enhanced ground proximity warning system
• EGT: Exhaust gas temperature
• EHS: Enhanced surveillance
• EHSI: Electronic horizontal situation indicator
• EICAS: Engine indication crew alerting system
• EIS: Electronic Instrument System
• ELT: Emergency locator transmitter
• ENC: Electronic noise canceling
• ENG: Engine
• ENR: Electronic noise reduction
• EPR: Engine pressure ratio
• EPU: Emergency Power Unit
• ERAM: En Route Automation Modernization
• ETOP: Extended-range twin-engine operation

  F

• FAA: Federal Aviation Administration
• FADEC: Full authority digital engine control
• FAF: Final approach fix
• FANS: Future Air Navigation System
• FAS: Final Approach Segment
• FAT: Free air temperature
• FATO: Final Approach and Take-off Area
• FBO: Fixed Base Operator
• FBW: Fly-by-wire
• FCC: Flight Control Computer
• FCMC: Fuel Control & Monitoring Computer
• FCS: Flight Control System
• FD: Flight Director
• FDAU: Flight-data acquisition unit
• FDPS: Flight plan Data Processing System
• FDR: Flight Data Recorder
• FDRS: Flight data recorder system
• FDU: Flux detector unit
• FF: Fuel flow
• FG: Flight Guidance
• FIC: Flight Information Centre
• FIKI: Flight Into Known Ice
• FIS-B: Flight information services – broadcast
• FL: Flight Level
• FLIR: Forward-looking infra-red
• FLTA: Forward-looking terrain avoidance
• FMA: Flight Mode Annunciator
• FMGS: Flight Management & Guidance System
• FMS: Flight management system
• FOB: Fuel On-Board
• FOD: Foreign object damage
• FQIS: Fuel Quantity Indication System
• FREQ: Frequency
• FSS: Flight service station
• FWS: Flight warning system
• FYDS: Flight director/ Yaw damper system

  G

• GA: Go Around
• GAST: GBAS Approach Service Type
• GBAS: Ground based augmentation 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: GBAS Landing System
• GLU: GPS landing unit
• GMT: Greenwich Mean Time
• GND: Ground
• GNSS: Global Navigation Satellite System
• GO: Go Around
• GPS: Global Positioning System
• GPWC: Ground proximity warning computer
• GPWS: Ground proximity warning system
• G/S: Glide Slope
• GS: Ground speed

  H

• "Hg: Symbol for unit of pressure, Inch of Mercury
• HDG: Heading
• HDG SEL: Heading select
• HDOP: Horizontal dilution of precision
• HF: High frequency
• HHLD: Heading hold
• HIRF: High intensity radiated field
• HMD: Helmet-mounted display
• HPR: High Pressure Rotor
• HSD: High-speed data
• HSI: Horizontal situation indicator
• HSL: Heading select
• HUMS: Health and usage monitoring systems
• HUD: Head-up display
• Hz: Symbol for unit of frequency, Hertz

  I

• IAF: Initial Approach Fix
• IAP: Instrument approach procedure
• IAS: Indicated airspeed
• IAS: Intermediate Approach Segment
• ID: Identify/Identification or identifier
• IDENT: Identify/identifier
• IDS: Information display system or integrated display system
• IF: Intermediate Fix
• IFE: In-flight entertainment
• IFF: Identification Friend or Foe
• IFICS: Integrated Flight Instrument and Control System
• IFR: Instrument Flight Rules
• ILS: Instrument landing system
• IMC: Instrument meteorological conditions
• IND: Indicator
• InHg: Inch of Mercury
• INS: Inertial Navigation System
• IRS: Inertial Reference System
• IRU: Inertial reference unit
• ISA: International Standard Atmosphere
• ISP: Integrated switching panel
• ISIS: Integrated standby instrument system
• ITT: Interstage turbine temperature
• IVSI: Instantaneous vertical speed indicator

  J

• JTIDS: Joint Tactical Information Distribution System

  K

• KIAS: Knots Indicated airspeed
• KTAS: Knots true airspeed

  L

• 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
• LOPA: Location of Passenger Accommodations
• LORAN: Long-range navigation
• LPR: Low Pressure Rotor
• LPV: Localizer performance with vertical guidance
• LRU: Line-replaceable unit
• LTE: Loss of Tail Rotor Effectiveness Helicopters
• LVP: Low visibility procedures, a designated state of operations at aerodromes where instrument approaches and low visibility takeoff procedures are using during inclement weather
• LX: Lightning

  M

• MAP: Manifold absolute pressure or missed approach point
• MAPS: Minimum Aviation Performance Standards
• MAHF: Missed Approach Holding Fix
• MAPt: Missed Approach Point
• MAP: Missed Approach Procedure
• MB: Marker beacon
• MCBF: Mean cycles between failures
• MCDU: Multi-purpose/Multi-function Control and Display Unit
• MDA: Minimum Descent Altitude
• MDH: Minimum Descent Height
• MEA: Minimum en-route altitude
• MEL: Minimum equipment list
• METAR: Meteorological Aerodrome Report
• MCP: Mode control panel
• MF: Medium frequency
• MFD: Multi-function display
• MFDS: Multi-function display system
• MIC: Microphone
• MIDS: Multifunctional information distribution system
• MILSPEC: Military specification
• MKP: Multi-function Keypad
• MKR: Marker beacon
• MLS: Microwave landing system
• MM: Middle marker
• MMD: Moving map display
• MNPS: Minimum navigation performance specifications
• 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
• MOPS: Minimum Operational Performance Standard
• MORA: Minimum Off Route Altitude
• MOSArt: Modular Open System Architecture
• MPU: Multifunction Processor Unit
• MSA: Minimum safe altitude
• MSD: Minimum Stabilization Distance
• MSG: Message
• MSP: Modes S-Specific Protocol
• MSSS: Mode S-Specific Services
• MTBF: Mean time between failures
• MTBUR: Mean time between unscheduled removals
• MTTF: Mean time to failure
• MVA: Minimum vectoring altitude
• MVFR: Marginal visual flight rules
• MZFW: Maximum Zero Fuel Weight

  N

• N1: Low Pressure rotor speed
• N2: High Pressure rotor speed
• NAS: National Airspace System
• NAV: Navigation receiver
• Navaid: Navigational aid
• NAVCOMM, NAV/COM or NAV-COM: Combination navigation and communications equipment.
• NAVSTAR-GPS: NAVigation Satellite Timing And Ranging
• NCAT: National Center for Aviation Training
• NCATT: National Center for Aircraft Technician Training
• ND: Navigation display
• NDB: Non-directional radio beacon
• NFF: No fault found
• NGS: Nitrogen Generation System, found in aircraft to reduce fire risk in fuel tanks.
• NHA: Next Higher Assembly.
• NM or NMI: Nautical mile
• NORDO: No radio
• NoTAM: Notice to Airmen
• NOZ: Normal Operating Zone
• NPA: Non-precision approach
• NVD: Night vision device
• NVG: Night vision goggles
• NTSB: National Transportation Safety Board
• NTZ: No-Transgression Zone

  O

• OAS: Obstacle Assessment Surface
• OAT: Outside air temperature
• OBI: Omnibearing indicator
• OBS: Omnibearing selector
• OCC: Operations control center
• OCH: Obstacle Clearance Height
• OFZ: Obstacle Free Zone
• OIS: Obstacle Identification Surface
• OIS: Operational Information System
• OM: Outer marker
• OWE/OEW: Operating Weight Empty/Operating empty weight

  P

• PA: Public address system
• PAEW: Personnel and equipment working
• PAL: Pilot Activated Lighting
• PAPI: Precision approach path indicator
• PAR: Precision approach radar
• PCL: Pilot Controlled Lighting
• P-Code: GPS precision code
• PD: Profile descent
• PDC: Pre-Departure Clearance
• PDOP: Position dilution of precision
• PESA: Passive electronically scanned array
• PFD: Primary flight display or primary flight director
• PMG: Permanent magnet generator
• PND: Primary navigation display
• PNR: Passive noise reduction
• POF: Phase of flight
• POH: Pilot's Operating Handbook
• POS: Position
• P-RNAV: precision area navigation
• PRA: Pre-recorded announcement
• PSR: Primary surveillance radar
• PSU: Passenger service unit
• PTT: Push-to-talk

  Q

• QAR: Quick Access Recorder
• QNH: Barometric pressure adjusted to sea level
• QRH: Quick Reference Handbook

  R

• RA: Resolution advisory
• RAAS: Runway Awareness and Advisory System
• Rad Alt: Radio Altitude
• Radar: RAdio Detection And Ranging
• RAI: Radio altimeter indicator
• RAIM: Receiver-autonomous integrity monitoring, also remote autonomous integrity monitoring
• RALT: Radar or radio altimeter
• RAT: Ram air turbine
• RCR: Reverse current relay
• RCVR: Receiver
• RDH: Reference Datum Height
• RDMI: Radio distance magnetic indicator
• RDP: Radar data processing system
• RDR: Radar
• REF: Reference
• REIL: Runway end identifier lights
• REL: Relative
• RF: Radio frequency
• RFI: Radio frequency interference
• RHSM: Reduced horizontal separation minimal
• RLG: Ring laser gyroscope
• RLY: Relay
• RMI: Radio magnetic indicator
• RNAV: Area navigation
• RNG: Range
• RNP: Required Navigation Performance
• ROC: Rate Of Climb
• ROD: Rate Of Descent
• RPA: Remotely Piloted Aircraft
• RPAS: Remotely Piloted Aircraft System
• RPM: Revolutions per minute
• RSP: Reversion switch panel
• RTE: Route
• RTO: Rejected takeoff
• RVR: Runway visual range
• RVSM: Reduced vertical separation minimum
• RX: Receiver

  S

• SAR: Search and Rescue, Smart ACMS Recorder
• SAT: Static air temperature
• SATCOM: Satellite communication
• SATNAV: Satellite navigation
• SD: Secure digital
• SDF: Simplified directional facility
• SDU: Satellite data unit
• SELCAL: Selective calling
• SID: Standard Instrument Departure
• SIU: Satellite interface unit
• SMS: Short Messaging Service
• SNR: Signal-to-noise ratio
• SPKR: Speaker
• SQ or SQL: Squelch
• SRS: Speed Reference System
• 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
• STCA: Short-Term Conflict Alert
• STP: Standard temperature and pressure
• SUA: Special use airspace

  T

• TA: Traffic advisory
• TAA: Terminal Arrival Altitude
• 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 and warning system
• TBO: Time before overhaul, or time between overhaul
• TCA: Throttle control assembly, or terminal control area
• TCAS: Traffic collision avoidance system
• TCF: Terrain clearance floor
• TCN: TACAN
• TCU: TACAN control unit
• TDOP: Time dilution of precision
• TDR: Transponder
• TERPS: Terminal instrument procedures, or terminal en route procedures
• TFR: Temporary flight restrictions
• TFT: Thin-film transistor
• TGT: Turbine gas temperature, or target
• THR: Threshold
• THDG: True heading
• TIS: Traffic information service
• TIT: Turbine Inlet Temperature
• TK: Track angle
• TKE: Track-angle error
• TLA: Thrust Lever Angle
• TLA: Three-letter acronym
• TOC: Top of climb
• TOD: Top of Descent point
• TOGA or TO/GA: Takeoff/Go-around switch, Takeoff/go-around thrust
• TOT: Turbine outlet temperature
• TR or T/R: Transmitter receiver or transceiver
• T/R: Thrust Reverser or Tail Rotor
• TRACON: Terminal radar approach control
• TRANS: Transmit, Transmission, or Transition
• TRK: Track
• TRP: Mode S transponder
• TTL: Tuned to Localizer
• 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
• Twr: Tower
• TX: Transmit

  U

• UAC: Upper Area Control
• UART: Universal asynchronous receiver transmitter
• UAV: Unmanned aerial vehicle
• UHF: Ultra-high frequency
• ULB: Underwater locator beacon
• USB: Universal Serial Bus
• UTC: Universal Time Coordinate

  V

• V: Volts or voltage
• V/L: VOR/Localizer
• V/NAV: Vertical navigation
• V/R: Voltage regulator
• V/REF: Reference velocity
• V/S: Vertical speed
• V/TRK: Vertical track
• VASI: Visual approach slope indicator
• VASIS: Visual approach slope indicator
• VDF: VHF Direction Finding
• VDL: VHF Data Link
• VDR: VHF digital radio
• VFO: Variable frequency oscillator
• VFR: Visual flight rules
• VG/DG: Vertical gyroscope/directional gyroscope
• VGA: Video Graphics Array
• VHF: Very high frequency
• VMC: Visual meteorological conditions or minimum control speed with critical engine out
• VNE: Never exceed speed
• VNO: Maximum structural cruising speed
• VNR: VHF navigation receiver
• VOR: VHF omnidirectional range and ranging
• VOR/DME: VOR with Distance measuring equipment
• VOR/MB: VOR marker beacon
• VORTAC: VOR and TACAN combination
• VOX: Voice transmission
• VPA: Vertical Path Approach
• VPATH: Vertical path
• VRP: Visual Point of Reference
• VSI: Vertical speed indicator
• VSM: Vertical separation limit
• VSO: Stall speed in landing configuration
• VSWR: Voltage–standing wave ratio
• VX: Speed for best angle of climb
• VY: Speed for best rate of climb

  W

• WAAS: Wide Area Augmentation System
• WD: Wind direction
• 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
• WS: Wind shear
• WX: Weather
• WXR: Weather radar system
• WYPT: Waypoint

  X

• XCVR: Transceiver
• XFR: Transfer
• XMIT: Transmit
• XMSN: Transmission
• XMTR: Transmitter
• XPDR: Transponder
• XTK: Crosstrack
• X-Start: Cross-start. Use the air pressure or electrical power from a working engine.

  Y

• YD: Yaw damper
• Y : YAW

  Z

• ZFW: Zero Fuel Weight