List of aviation, avionics, aerospace and aeronautical abbreviations

Below are abbreviations used in aviation, avionics, aerospace, and aeronautics.

A

Abbreviation Term Notes
A/A Air to air TACAN function
A/C Aircraft[1]
AC Altocumulus Cloud type
ACC Altocumulus castellanus Cloud type
ACC Area Control Centre
A/D Aerodrome
ACT Alternative Configuration Tool
A/F Autofeather
A/FD Airport/Facility Directory
A/P Autopilot
AAE Above aerodrome elevation[1] In aviation, above aerodrome level (AAL), or above aerodrome elevation (AAE), denotes that an altitude is given above the nearest aerodrome or airport.
AAIB Air Accidents Investigation Branch United Kingdom
AAIM Aircraft Autonomous Integrity Monitoring
AAO Assumed adverse obstacle
AAS Airport advisory service[1]
AC Advisory circular[2] Information and guidance publication
ACAM Aircraft continuous airworthiness monitoring
ACARS Aircraft Communications Addressing and Reporting System
ACAS Airborne collision avoidance system
ACC Area control centre[1]
ACC Active clearance control Turbine engine system
ACC Accessory In gas turbine engine
ACE Actuator control electronics
ACFT Aircraft[3]
ACI Airports Council International
ACLS Automatic carrier landing system Aircraft carrier operations
ACM Air cycle machine Part of A/C air conditioning system
ACMS Aircraft condition monitoring system
ACP Audio Control Panel
ACR Avionic Communication Router
ACS1 Airman Certification Standards[4] FAA pilot testing
ACS2 Audio control system
ACU1 Air condition unit
ACU2 Alternator control unit[2] Protection from alternator over-voltage.
AD Airworthiness Directive
ADA Advisory area
ADAHRS Air data attitude heading reference system
ADC Air data computer
ADD Acceptable deferred defect
ADF Automatic direction finder Navigation equipment
ADI Attitude Director Indicator
ADIRS Air Data Inertial Reference System
ADIRU Air Data Inertial Reference Unit
ADIZ Air defense identification zone
ADJ Adjustment Mechanical term
ADM1 Aeronautical decision-making[5] Piloting term of judgment
ADM2 Air data module
ADN Aircraft Data Network Ethernet derivative for Commercial Aircraft
ADS1 Air data system
ADS2 Automatic dependent surveillance
ADS-A Automatic dependent surveillance – address
ADS-B Automatic dependent surveillance – broadcast
ADS-C Automatic dependent surveillance – contract
ADV Arbeitsgemeinschaft Deutscher Verkehrsflughäfen "German Airports Association"
AEA Association of European Airlines
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
AFE Above field elevation
AFIS Airborne flight information system Also called automatic flight information service
AFM Aircraft flight manual
AFS Aeronautical fixed service
AFT Aft The direction against the aircraft movement
AFTN Aeronautical Fixed Telecommunication Network
AGACS Automatic ground–air communications system Also known as ATCSS or data link
AGB Accessory gear box Mainly used in turbine engine
AGC Automatic gain control
AGDL Air–ground data link
AGL Above ground level
AHC Attitude heading control
AHRS Attitude and heading reference system
AIDS Aircraft integrated data system
AIM Aeronautical Information Manual
AIP Aeronautical Information Publication
AIRAC Aeronautical information regulation and control
AIRMET Air-mission's Meteorological Advisory[6] In-flight advisory given over 126.7
AIS Aeronautical Information Services A place mostly for presenting Flight Plans and filing reports
AIXM Aeronautical information exchange model
ALC Automatic level control
ALI Airworthiness Limitation Item
ALNA Airline network architecture
ALS Approach lighting system
ALT1 Alternate
ALT2 Altimeter
ALT3 Altitude
ALT hold Altitude hold mode
ALTS Altitude select
ALUM Aluminum
AMC Acceptable Means of Compliance (EASA)
AME Aircraft Maintenance Engineer
AME Aviation Medical Examiner
AMLCD Active-matrix liquid-crystal display
AMM Aircraft Maintenance Manual
AMO Approved Maintenance Organization
AMS Air management system
AMSL Above mean sea level
AMP Aircraft maintenance program
AMT Aircraft Maintenance Technician
ANC Active noise cancellation
AND Aircraft Nose Down
ANN Annunciator panel Caution warning system normally containing visual and audio alerts to the pilot
ANPT Aeronautical national pipe taper
ANR Active noise reduction
ANSP1 Air navigation service provider
ANSP2 Authorization of Aircraft Network Security Program (FAA)
ANT Antenna (radio)
ANSOG Airport Network Security Operator Guidance (Boeing)
A/O Air oil In turbine engines
AOA Angle of attack
AOC1 Air operator's certificate
AOC2 Aeronautical operational control
AOG Aircraft on ground
AOM1 Aircraft operations manual
AOM2 Airport/aerodrome operating minima
AOP Airport operating plan
AP Autopilot
A/P Airplane (US), Aeroplane (ICAO)
APARS Automatic pressure altitude reporting system
APC Auto pilot computer
APIRS Attitude and positioning inertial reference system
APOA Airport of arrival
APOD Airport of departure
APM Aircraft personality module
APP Appendix
APP Approach Control ATC
APPL Application
APPROX Approximately
APS Auto pilot system
APT Airport
APU Auxiliary power unit
APV Approach procedure with vertical guidance Instrumental approach
AQP Advanced Qualification Program FAA training and testing
AR Airworthiness review
AR Authorization required
AR As required
ARC Airworthiness review certificate
ARINC Aeronautical Radio Inc.
ARO Airport reservation office
ARP Aerodrome reference point
ARTCC Air route traffic control centers
ASAS Airborne Separation Assurance System
ASD Aircraft situation display
ASDA Accelerate Stop Distance Available
ASDE-X Airport Surface Detection Equipment, Model X
ASDL Aeronautical satellite data link
ASI Airspeed indicator
ASL Above sea level[1]
ASLO Aircraft Security Logging Overview
ASM Airspace management
ASM Available seat miles
A-SMGCS Advanced Surface Movement Guidance and Control System
ASOS Automated Surface Observation System
assy Assembly
A/S Anti-Skid
ASR Airport surveillance radar
ASU Avionics switching unit
A/T Autothrottle Also 'AT'
A/THR Autothrust
ATA Air Transport Association
ATAG Air Transport Action Group A coalition of aviation industry experts focusing on sustainable development issues.
ATC Air traffic control
ATCC Air traffic control centre
ATCO Air traffic controller
ATCT Airport traffic control tower
ATCRBS Air traffic control radar beacon system
ATCSS Air traffic control signalling system
ATD Actual time of departure Equivalent to off-block time[7]
ATE Advanced Technology Engine
ATF Aerodrome traffic frequency
ATFM Air traffic flow management
ATIS Automatic Terminal Information Service
ATM Air traffic management
ATN Aeronautical Telecommunication Network
ATO Approved Training Organisation
ATPL Airline Transport Pilot Licence
ATQP Alternative Training and Qualification Programme
ATR1 1 Air transportable racking
ATR2 Automatic thrust restoration
ATS Air traffic service
ATSAW Airborne traffic situational awareness
ATSU Air traffic services unit Avionics LRU for ACARS
ATT Attitude
ATTCS Automatic Take-off Thrust Control System
AUPRTA Airplane Upset Prevention & Recovery Training Aid
AVAIL Available
Avionics Aviation electronics
AVSA "Adjust vertical speed adjust" TCAS Voice command to adjust traffic separation
AWACS Airborne Warning and Control System Airborne early warning and control (AEW&C) or Boeing E-3 Sentry
AWBS Aviation weather briefing service[6] Available at designated FSS's
AWG American Wire Gage The larger the size number, the smaller the wire diameter.
AWIS Aviation weather information service[6] Available at FSS
AWO All weather operations
AWOS Automated weather observation system[6] Automated METAR reporting system
AWWS Aviation weather web site[8] In Canada

B

Abbreviation Term Notes
B RNAV Basic area navigation
BARO Barometric indication, setting or pressure
baro-VNAV Barometric vertical navigation
BC Back course Or 'BCRS'
BCAA Belgian Civil Aviation Authority
BDC bottom dead centre[1] Piston engine
BDI Bearing distance indicator
BFL Balanced field length
BFR Biennial flight review
BGAN Broadcast Global Area Network
BER Beyond economic repair Hull loss
BHP Brake horsepower[1]
BITE Built-In Test Equipment
BL Butt Line
BME Bridge Mounted Equipment
B/P Blue Print
BPR bypass ratio
BOM bill of material
BTV Brake-to-Vacate System A new feature introduced by Airbus A380
BWC bird watch condition
BVID Barely Visible Impact Damage
BVR Beyond Visual Range

C

Abbreviation Term Notes
C2 command and control
CA Captain
CAA Civil Aviation Authority
CACTCS Cabin Air Conditioning and Temperature Control System (Pronounced "Cactus")
CAI Caution Advisory Panel Sometimes spelled "caution-advisory" or "caution/advisory". Also known as annunciator panel or Centralized Warning Panel (CWP)
CAM cockpit area microphone Part of a cockpit voice recorder
CAME Continuing Airworthiness Management Exposition
CAMO Continuing Airworthiness Management Organisation
CAMP Continuous Airworthiness Maintenance Program (FAA)
CAN bus Controller Area Network
CANSO Civil Air Navigation Services Organisation
CAP cabin attendant panel
CAR civil aviation regulation
CARs civil aviation regulations[9][10]
CARS Canadian Aviation Regulations
CAS calibrated airspeed
CASS Commercial Air Service Standards
CASS continuing analysis and surveillance system
CAT (I–IIIc) Operational performance Category 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

CAT1 clear air turbulence[1]
CAT2 Commercial Air Transport
CAVOK Ceiling and Visibility OK[11] Visibility is at least 10 kilometres and no clouds below 5000 feet with no forecasted significant weather change such as precipitation.
CAVU Ceiling and Visibility Unlimited
CAW continuing airworthiness (EASA)
CB Cumulonimbus cloud
CBT computer-based training
CCRs closed circuit mixed gas rebreathers
CCRs constant current regulators
CDA Continuous descent approach
CDCCL critical design configuration control limitation
CDI course deviation indicator
CDU Control Display Unit
CDFA Continuous Descent Final Approach
NUO
CDTI Cockpit display of traffic information
CDL configuration deviation list
CDU control/display unit
CFIT controlled flight into terrain
CFG constant frequency generator
CFR Code of Federal Regulations In the United States
CG center of gravity
CH Course Heading
CHDO certificate-holding district office (FAA)
CHP Course Heading Panel
CHT Cylinder Head Temperature (Piston engine aviation)
CI cost index
CID Customer induced damage
C/L Centre line
CL checklist A flight deck manual, usually part of a Quick Reference Handbook
CLR Clear Seen on GFA and is used for sky coverage
CMC central maintenance computer
CMM component maintenance manual
CMO Certificate Management Office FAA
CMV converted meteorological visibility
CMPA complex motor-powered aircraft
CMU Communications Management Unit
CNS Communication, navigation and surveillance
CNS/ATM Communication, navigation and surveillance / Air traffic management[12]
CODEC Coder/decoder
CofA Certificate of airworthiness
COMM or COM Communications transceiver, Communications receiver, or Communications radio transmitter Now, normally: either VHF or UHF; HF communications avionics are usually abbreviated simply HF
CORSIA Carbon Offsetting and Reduction Scheme for International Aviation
COTS Commercial off-the-shelf
CPA Closest point of approach
CPDLC controller–pilot data link communications
CPR Changed product rule EASA
CPS Cycles per second
CRD Comment-response document (EASA) Part of rule making process
CRES Corrosion resistant steel
CRM Crew resource management
CRT Cathode-ray tube
CS certification specification (EASA)
CSD constant speed drive
CSDB Commercial Standard Digital Bus
CSDB Collins Standard Digital Bus
CSN Cycles since new Normally measured in FC or EFC for an aircraft, engine or component
CSO cycles since overhaul
CSS cabin services system
CSU constant speed unit
CSCT Configuration Item Signer Crater Tool Boeing
CTAF common traffic advisory frequency
CTR controlled traffic region/control zone
CV/DFDR Cockpit voice and digital flight data recorder See Flight recorder
CVR cockpit voice recorder See Flight recorder
CWS control wheel steering

D

Abbreviation Term Notes
D Compass Deviation
DA/H decision altitude/height (rel. to THR) See instrument landing system
DA1 Decision Altitude Precision approach or vertical guidance
DA2 density altitude
DA3 Drift angle
DAH design approval holder (EASA)
DAPs Downlink of aircraft parameters
DBER damaged beyond economic repair Hull loss
DCDU Datalink control and display unit
DCL Departure Clearance via CPDLC
DCP Display control panel
DDG Dispatch deviation guide https://fsims.faa.gov/WDocs/8400.10%20Air%20Transp%20Ops%20Insp%20Handbk/Volume%204.%20AIRCRAFT%20EQUIPMENT%20AND%20OPERATIONAL%20AUTHORIZATIONS/Vol%204-Chap%204-Sec%203.htm
DEFDARS Digital Expandable Flight Data Acquisition and Recording System
DER departure end of runway
DER Designated Engineering Representative
DEU display electronic unit
DFDR Digital Flight Data Recorder See flight recorder
DFMC Dual Frequency Multiple Constellation
DG directional gyro
DGPS differential GPS[1]
DGR Dangerous Goods Regulation
DH Decision height Precision approach, referred to threshold elevation
DIA diameter
DLR datalink recorder
DLR German Aerospace Center / Deutsches Zentrum für Luft- und Raumfahrt e.V.
DME distance measuring equipment
DME Designated Mechanic Examiner[2] A person appointed by the FAA
DMI deferred maintenance item
DNC Direct noise canceling
DO design organization
DOA design organization approval EASA
DODAR diagnose, options, decide, act/assign, review
DOM design organization manual
DOW dry operational weight
DP Departure Procedures
DPU Display Processor Unit
DR dead reckoning
DRMC Direct Reading Magnetic Compass
DSP Digital signal processing
DTO declared training organisation
DTU Data transfer unit
DUATS Direct User Access Terminal Service
DVE Degraded Visual Environment

E

Abbreviation Term
EA engineering authorisation
EADI Electronic Attitude Direction Indicator
EAS equivalent airspeed[1]
EASA European Aviation Safety Agency
EAT expected approach time[1]
EBOM engineering Bill of Material
EBU engine build-up
EC engineering control (also E/C)
ECAM electronic centralised aircraft monitor
ECET end of civil evening twilight
ECR Engineering Change Request
ECS Environmental control system
ECU Engine Control Unit (=EEC)
EDR engineering data record
EDTO extended diversion time operations
EEC electronic engine control
EET estimated elapsed time
EFB electronic flight bag
EFC1 Engine Flight Cycle
EFC2 expect further clearance
EFD Electronic flight display
EFFRA engine failure flap retraction altitude
EFIS electronic flight instrument system
EFH Engine Flight Hour
EFP engine failure procedure
EFS elevator feel shift
EFTO engine failure on take-off
EFVS Enhanced flight visual system
EGPWS enhanced ground proximity warning system
EGI Embedded GPS Inertial
EGNOS European Geostationary Navigation Overlay Service
EGT exhaust gas temperature
EHM engine health monitoring
EHS Enhanced surveillance
EHSI Electronic Horizontal Situation Indicator
EICAS engine-indicating and crew-alerting system
EIS Electronic Instrument System
E-LSA experimental light-sport aircraft
ELAC elevator and aileron computer
ELOS Equivalent Level of Safety
ELT emergency locator transmitter
EMAS engineered materials arresting system
EMDP electric motor driven pump
ENC Electronic noise canceling
ENCASIA European Network of Civil Aviation Safety Investigation Authorities
ENG engine
ENR Electronic noise reduction
EOBT estimated off-blocktime
EPA European part approval (EASA)
EPR engine pressure ratio
EPU Emergency Power Unit
ERAM En Route Automation Modernization
ERM engineering request for maintenance
ESA emergency safe altitude
ETA estimated time of arrival
ETD estimated time of departure[1]
ETE estimated time en route[1]
ETL effective translational lift
ETOPS Extended-range Twin-engine Operation Performance Standards
ETSO European Technical Standard Order, issued by EASA; see TSO
EUROCAE European Organisation for Civil Aviation Equipment
EVAS Emergency Vision Assurance System
EVSI Enhanced Vision Systems Instrument
EVS Enhanced Vision Systems
EW Empty Weight

F

Abbreviation Term Notes
FAA Federal Aviation Administration U.S. Department of Transportation agency
FAC Final approach course
FACF final approach course fix Point at which the final approach descent is begun
FADEC full authority digital engine control Engine equipment
FAC Flight Augmentation computer Avionics
FAF final approach fix
FAF first available flight Airline operations
FALS full approach lighting system
FANS Future Air Navigation System Avionics
FAP final approach point
FAP forward attendant panel Aircraft equipment
FAR Federal Aviation Regulation FAA regulation
FAR/AIM Federal Aviation Regulation /
Aeronautical Information Manual 		Bundle of FAA regulations and Aeronautical Manual[13]
FAROS final approach runway occupancy signal
FAS final approach segment
FAT Free air temperature
FATO final approach and take off
FB Winds aloft World Meteorological Organization abbrev. see also FD
FBO fixed-base operator Airfield operations
FBS fixed base simulator Flight crew training
FBW fly-by-wire
FCC Flight Control Computer
FC flight crew
FCF functional flight check Check functionality after maintenance
FCMC Fuel Control & Monitoring Computer
FCOM flight crew operating manual Aircraft operations
FCS flight control system
FCTM flight crew training manual
FCU fuel control unit In turbine engines
FD flight director Avionics
FD upper winds and temperature forecast[1] US and Canada abbrev. See also FB
FDAU flight-data acquisition unit
FDM flight data monitoring Operations planning
FDP flight duty period
FDPS flight plan data processing system Flight planning
FDR flight data recorder Avionics. Also known as 'black box'.
FDRS flight data recorder system Avionics
FDTL flight duty time limitations
FDU flux detector unit
FEP final end point
FF fuel flow
FFDZ free fall drop zone (parachutists)
FFS full flight simulator Flight crew training
FG Flight Guidance
FIC flight information centre
FIDO Fog Investigation and Dispersal Operation Airfield operations
FIKI Flight Into Known Icing Aircraft operations
FIR flight information region ATC
FIS Federal Inspection Services
FIS-B Flight information services – broadcast
FISE flight information service enroute
FL flight level ATC
FLIR Forward-looking infra-red
FLTA Forward-looking terrain avoidance
FM frequency modulation Example: FM immunity
FMA flight mode annunciator Equipment
FMC flight management computer (part of a FMS) Avionics
FMGC Flight management and guidance computer Avionics. Also FMGS: Flight Management & Guidance System
FMS flight management system Avionics
FO first officer Flight crew
FOB Fuel On-Board
FOD foreign object damage Airfield operations
FOO flight operations officer Airline employee
FOQA flight operational quality assurance
FPA flight path angle
FPL filed flight plan ATC
FPM feet per minute
FQIS Fuel Quantity Indication System
FREQ Frequency
FS Fuselage station
FSDO Flight Standards District Office (FAA)
FSF Flight Safety Foundation U.S.-based nonprofit organisation
FSIMS Flight Standards Information Management System (FAA)
FSS flight service station
FTD flight training device Flight crew training
FTL flight time limitations
FVU flux valve unit Equipment
FWS Flight warning system
FYDS Flight director / yaw damper system

G

Abbreviation Term Notes
GA general aviation
G/A or GA go-around Aborted landing procedure
GAST GBAS Approach Service Type
GBAS Ground based augmentation system
GCAS Ground collision avoidance system
GBST ground-based, software tool Airfield operations
GCA Ground-controlled approach Airfield operations
GCU generator control unit
GDOP Geometric dilution of precision
GEA Ground effect area
GGS Global positioning system ground station
GHz Gigahertz
GLOC g-induced loss of consciousness "g" Is acceleration relevant to the acceleration caused by gravity
GLONASS Global Navigation Satellite System Or GNSS
GLNS GPS Landing and Navigation System
GLNU GPS Landing and Navigation Unit
GLS GBAS Landing System
GLU GPS landing unit
GM guidance material (EASA)
GMM general maintenance manual
GMT Greenwich Mean Time
GND ground Airfield operations
GP glide path See instrument landing system
GPP general practices and procedures
GPS Global Positioning System Avionics
GPU Ground Power Unit Aerospace Ground Equipment
GPWS ground proximity warning system Avionics
G/S glideslope Avionics
GS groundspeed
GSE ground support equipment Aerospace ground equipment
GSPT Gross shop processing time
GSPU Glider snatch pick-up
GUMPS Gas, Undercarriage, Mixture, Propeller, Seat belts/Switches Mental checklist before landing

H

Abbreviation Term Notes
H Heavy Wake turbulence category
H High
HAA Height above airport
HAT Height Above Touchdown
HAZMAT Hazardous Material
HBCS High Bandwidth Connectivity System
HDB Horizontal Deviation Bar (GS)
HDG Heading Navigation
HDG SEL Heading select Navigation
HDI Horizontal Deviation Indicator
HDOP Horizontal dilution of precision
HF High frequency
HFE Human Factors Engineering[14]
HFES Human Factors and Ergonomics Society U.S.-based nonprofit organisation
"Hg Inch of Mercury Symbol for unit of pressure
HHLD Heading hold Navigation
HIGE hover in ground effect Helicopter operations
HIRL High Intensity Runway lighting Airfield operations
HIRO High Intensity Runway Operation Airfield operations
HIRTA High Intensity Radio Transmission Area
HIWAS Hazardous Inflight Weather Advisory Service
HL Height loss
HLD hold Maintain same altitude or speed or direction
HMG hydraulic motor generator
HMD Helmet-mounted display
HMU hydro-mechanical unit In turbine engine
HOGE hover out of ground effect Helicopter operations
HOTAS Hands On Throttle And Stick
HPA human-powered aircraft Aircraft type
HPC high pressure compressor In turbine engine
HPR High Pressure Rotor
HPT high pressure turbine In turbine engines
HPTACC high pressure turbine active clearance control Mainly used in turbofan engines
HSD High-speed data
HSI horizontal situation indicator Avionics
HSL Heading select
HUD head-up display Avionics
HUM Human Remains
HUMS Health and usage monitoring systems
HW headwind
HYD hydraulic Aircraft equipment
HYDIM hydraulic interface module
Hz Hertz Symbol for unit of frequency

I

Abbreviation Term Notes
IAC instrument approach chart
IAF initial approach fix
IAN Integrated Approach Navigation IAN approaches provide the functions, indications and alerting features similar to an ILS approach (B737 FCTM)
IAP instrument approach procedure
IAS indicated airspeed
IATA International Air Transport Association
IB inboard
ICA Instructions for Continuous Airworthiness
ICAO International Civil Aviation Organization
ICAS International Council of the Aeronautical Sciences
ICD interface control document
ICO idle cut-off
ICTS ice-contaminated tailplane stall
ID identify/identification or identifier
IDENT identify/identifier
IDG integrated drive generator Combination of a CSD and generator in a single case
IDS information display system Or: integrated display system
IDT identify XPDR
IEPR integrated engine pressure ratio
IETM interactive electronic technical manual
IF intermediate approach fix Instrumental approach
IFA International Federation of Airworthiness
IFATCA International Federation of Air Traffic Controllers' Associations
IFE in-flight entertainment
IFF identification friend or foe
IFICS integrated flight instrument and control system British Aircraft Corporation, now British Aerospace
IFP instrument flight procedure
IFR instrument flight rules
IFSD in-flight shutdown
IGV inlet guide vane
ILS instrument landing system
IMC instrument meteorological conditions
IML inside mold line
IND indicator
InHg inch of mercury
INS inertial navigation system
IPC illustrated parts catalog (e.g. by Boeing, Airbus)
IR initial release
IRS inertial reference system
IRT instrument rating test
IRU inertial reference unit
IRVR instrumented runway visual range
ISA International Standard Atmosphere
ISFD integrated standby flight display
ISIS integrated standby instrument system
ISP integrated switching panel
ITAR International Traffic in Arms Regulations
ITT interstage turbine temperature
IVSI instantaneous vertical speed indicator

J

Abbreviation Term
JAA Joint Aviation Authorities
JAR Joint Aviation Requirements
JTIDS Joint Tactical Information Distribution System

K

Abbreviation Term
KCAS knots calibrated airspeed
KIAS knots indicated airspeed
KRE key risk element
KTAS knots true airspeed

L

Abbreviation Term Notes
L Light Wake turbulence category
LAAS Local Area Augmentation System
LADGPS Local Area Differential GPS
LAHSO Land And Hold Short Operations
LAME licensed aircraft maintenance engineer
LAT large air tanker A class of waterbomber
LCC low-cost carrier
LCD liquid crystal display
LCG load classification group
LCN load classification number
LDA landing distance available
LDA localizer type directional aid
LDGPS local area differential global positioning satellite
LDR landing distance required
LED light-emitting diode
LHO live human organs
LHS left hand seat Jargon for captain
LIR Loading Instruction Report
LKP last known position
LLC Life Limited Component
LLP Life Limited Part EASA, ICAO
LLZ localizer ILS approach
LM land and marine
LMM Locator middle marker
LNAV lateral navigation
LOA letter of authorization FAA
LOC localizer
LOC loss of control
LOCI loss of control inflight
LOFT line-oriented flight training
LOM limitation of movement
LOM locator outer marker
LOPA Location of Passenger Accommodations
LORAN Long-range navigation
LOTC loss of thrust control
LPC low pressure compressor In turbine engines
LPR Low Pressure Rotor
LPT low pressure turbine
LPTACC low pressure turbine active clearance control Mainly used in turbofan engines
LPV localizer performance with vertical guidance
LRC long range cruise
LRU line-replaceable unit
LSAP loadable software aircraft part (EASA) Introduced in RMP for technical records
LSAS longitudinal stability augmentation system
LTC line training captain
LTE Loss of Tail Rotor Effectiveness Helicopters
LTP landing threshold point
LVP low visibility procedures Designated state of operations at aerodromes where instrument approaches and low-visibility takeoff procedures are used during inclement weather
LW landing weight
LX Lightning
LZ landing zone

M

Abbreviation Term Notes
M medium Wake turbulence category
MAC mean aerodynamic chord
MAC mid-air collision
MAHF Missed Approach Holding Fix Used in RNAV
MANAB Manual of Word Abbreviations[15] Used in Canada
MAP manifold absolute pressure
MAP missed approach point Or: MAPt. Instrument approach.
MAPS Minimum Aviation Performance Standards
MATS Manual of Air Traffic Services
MB Marker beacon
MBC Main Base Check
MCAS Maneuvering Characteristics Augmentation System Held responsible for Boeing 737 MAX groundings
MCBF Mean cycles between failures
MCC Multi-crew cooperation
MCDU multifunction control display unit
MCH Manufacturer Certificate Holder TCCA; see also PAH and POA
MCP mode control panel
MCT maximum continuous thrust
MCDU multi control display unit
MDA minimum descent altitude Or: minimum decision altitude. Non-precision approach.
MDDR maintenance deferred defect record
MDH minimum descent height Or: minimum decision height. Non-precision approach.
MDM multi-disciplinary measure EASA
ME Manufacturing Engineer
MEA Minimum En-route Altitude
MEDEVAC medical evacuation
MEF maximum elevation figure
MMEL master minimum equipment list
MEL minimum equipment list
MEP multi-engine piston
METAR meteorological aerodrome report
MF Medium frequency
MFD multi-function display
MFDS multi-function display system
MFRA minimum flap retraction altitude
MH magnetic heading
MIC Microphone
MIDS Multifunctional information distribution system
MIJI Meaconing, intrusion, jamming, and interference[16]
MILSPEC Military specification
MKP Multi-function Keypad
MKR Marker beacon
ML maintenance laptop
MLDW maximum landing weight
MLG Main Landing Gear
MLS microwave landing system
MM middle marker
MMD Moving map display
MNPS Minimum navigation performance specifications
MOA Military operations area
MOCA Minimum Obstacle Clearance Altitude
Mode A Transponder pulse-code reporting
Mode B Transponder code and altitude reporting
Mode C Transponder code, altitude, and TCAS reporting
MOE maintenance organisation exposition
MOPS Minimum Operational Performance Standard
MORA Minimum Off Route Altitude
MOSArt Modular Open System Architecture
MP manifold pressure
MPL multi-crew pilot license
MPU Multifunction Processor Unit
MRB Material Review Board
MRO maintenance, repair, overhaul
MRO maintenance and repair organization
MROT Minimum Runway Occupancy Time
MRP Material Resources Planning
MRW maximum ramp weight
MSA minimum safe altitude / minimum sector altitude
MSD Minimum Stabilization Distance
MSDS Material Safety Data Sheet
MSG Message
MSL mean sea level
MSLW Max. Structural Landing Weight
MSP Modes S-Specific Protocol
MSSS Mode S-Specific Services
MSTOW Max. Structural Take-off Weight
MSZFW Max. Structural Zero Fuel Weight
MTBF Mean time between failures
MTBSV Mean time between shop visit
MTBUR Mean time between unscheduled removals
MTOW maximum take-off weight
MTTF Mean time to failure
MVA Minimum Vectoring Altitude
MVFR Marginal visual flight rules
MX Maintenance
MZFW Maximum Zero Fuel Weight

N

Abbreviation Term Notes
NADP noise abatement departure procedure
NAS National Airspace System United States
NAV Navigation receiver Normally VHF navigation receiver for VOR
Navaid Navigational aid Or: aid to navigation (ATON)
NAVCOMM Combination navigation and communications equipment Or: NAV/COM or NAV-COM. normally VHF navigation receiver integrated with VHF communications transceiver
NAVSTAR-GPS Navigation Satellite Timing And Ranging The space-borne or satellite navigation system
NCAT National Center for Aviation Training US educational facility
NCATT National Center for Aircraft Technician Training US educational facility
ND Navigation display
NDB non-directional beacon
NDT non-destructive testing
NFF No fault found Or: no trouble found (NTF) or no defect found (NDF)
NGS nitrogen generation system
NHA next higher assembly
NIST National Institute of Standards and Technology
NLG nose landing gear
NLR Netherlands Aerospace Research Centre
NM Nautical mile Or: NMI
NNC non-normal checklist
NNM non-normal maneuver (Boeing QRH - 737 Flight Crew Operations Manual)
NORAD North American Aerospace Defense Command US-Canadian military security agency
NORDO no radio
NOTAM Notice to air missions[17]
NOTAR no tail rotor[2] Helicopter control system
NOZ Normal Operating Zone Parallel runways operation
NPA non-precision approach Instrumental approach
NPA notice of proposed amendment EASA
NPRM notice of proposed rulemaking FAA
NRR noise reduction rating hearing protector attenuation
NRTC nonroutine task card
NVD Night-vision device Or: Night-vision goggles (NVG)
NTSB National Transportation Safety Board U.S. governmental agency
NTZ no-transgression zone Parallel runways operation

N numbers (turbines)

Abbreviation Term Notes
N# compressor speed[1] N1, N2, etc. refers to the specific compressor spool (in the order that air passes over them). (See: Jet engine)
Ng gas generator speed[1]
Nh high rotor speed[1]
Np power turbine speed[1]
Nr rotor speed (helicopters) Np and Nr are typically shown on the same gauge with two needles, both expressed in percent, so that the pilot can tell if the power turbine is driving the rotor or if it is freewheeling.

O

Abbreviation Term Notes
OAS Obstacle Assessment Surface
OAT outside air temperature
OBE overcome by events
OBI Omnibearing indicator See CDI
OBS omni-bearing selector
OCA obstacle clearance altitude
OCC Operations control center
OCCM on condition / condition monitored components
OCH obstacle clearance height
OEI one engine inoperative
OEM original equipment manufacturer
OFZ Obstacle Free Zone
OGV outlet guide vane
OHM overhaul manual
OIS obstacle identification surface Instrumental procedures
OIS Operational Information System
OM outer marker
OML outer mold line
ONS onboard network system
ONAT Onboard Network Access Terminal
O/R On Request
OTS out of service
OPC operational check
OPS/CHK operational check
OW operational weight
OWE/OEW Operating Weight Empty/Operating empty weight

P

Abbreviation Term Notes
P (as a prefix:) prohibited airspace
PA pressure altitude
PA Public address system
PAEW Personnel and equipment working
PAH production approval holder FAA; see also POA and MCH
PAL Pilot Activated Lighting
PANS-OPS procedures for air navigation services – aircraft operations
PAOG Pre Aircraft on Ground
PAPI precision approach path indicator
PAR precision approach radar
PATWAS Pilot's Automatic Telephone Weather Answering Service[6]
PAX passenger
PBCS performance-based communication and surveillance
PBD place bearing distance RNAV waypoint
PBE Protective Breathing Equipment
PBN Performance-Based Navigation
PC proficiency check
PCL Pilot Controlled Lighting
P-Code GPS precision code
PCN pavement classification number
PD Profile descent
PDA performance degradation allowance
PDAS public domain aeronautical software
PDC Pre-Departure Clearance
PDG procedure design gradient
PDM pilot decision making
PDOP Position dilution of precision
PDU power drive unit Flap actuation
PET point of equal time
PESA Passive electronically scanned array
PF pilot flying
PFAF precision final approach fix
PFD primary flight display Or: primary flight director
PIC Pilot In Command
PICUS Pilot In Command, under supervision[18]
PIO Pilot Induced Oscillations
PIP performance improvement package
PIREP Pilot Report
PJA Parachute Jumping Area
PJE Parachute jumping exercise
PM pilot monitoring
PMA Parts Manufacturer Approval
PMI Principal Maintenance Inspector
PMC power management computer Turbine engines
PMG permanent magnet generator
PN part number Also P/N
PND primary navigation display
PNF pilot not flying
PNR passive noise reduction
PNR Point of No Return
POA Production Organisation Approval EASA; see also PAH and MHC
POB persons on board
POF Phase of flight
POF Principles Of Flight
PO Pilot's Operating Handbook Sometimes referred to as a POH
POS Position
PPL private pilot licence
PPR prior permission required
PRA Pre-recorded announcement
P-RNAV
PS passenger step
PSAA Product support and assurance agreement
PSEU Proximity Switch Electronic Unit / B737
PSR point of safe return
PSR power supply reset
PSR primary surveillance radar
PSU passenger service unit
PTCU power transfer Control unit
PTF permit to fly
PTOL point take-off and landing
PTR Pilot Training Record
PTT push to talk
PYLD payload

Q

Abbreviation Term Notes
QAR quick access recorder
QCM quality and compliance monitoring
QEC quick engine change
QFE the Q-code for: Atmospheric pressure at aerodrome elevation (or at runway threshold)
QNE the Q-code for pressure altitude
QNH the Q-code for: Altimeter sub-scale setting to obtain elevation when on the ground, i.e. altitude above MSL
QRA quick reaction alert
QRH quick reference handbook
QTOL quiet take-off and landing[19]

R

Abbreviation Term Notes
R (as a prefix:) restricted airspace
RA radio altitude or radar altimeter
RA resolution advisory In the context of TCAS
RAAS Runway Awareness and Advisory System
RAAS remote airport advisory service
Rad Alt Radio Altitude
Radar RAdio Detection And Ranging
RAI Radio altimeter indicator
RAIM Receiver Autonomous Integrity Monitoring Or: remote autonomous integrity monitoring
RALT Radar or radio altimeter
RAREPS Weather Radar Reports[6] Provided by Air Traffic Controllers
RAS rectified air speed
RA(T) restricted area (temporary)
RAT ram air turbine
RCO remote communications outlet
RCR Reverse current relay
RCVR Radio receiver
RDH reference datum height For instrument landing system (ILS)
RDMI Radio distance magnetic indicator
RDP Radar data processing system
RDR Radar
REF Reference
REIL Runway end identifier lights
REL Relative
REO Repair engineering order
RESA runway end safety area
RF Radio frequency
RFF rescue and fire fighting
RFI Radio frequency interference
RFI recreational flight instructor
RGB reduction gear box
RHS right hand seat Jargon for first officer
RHSM reduced horizontal separation minimal
RIA regulatory impact assessment (EASA)
RII required inspection items
RLG Ring laser gyroscope
RLTC Remaining Life Time Cycle Counter to the limiter especially for LLPs in engines
RLY Relay
RMI radio magnetic indicator
RMP Radio Management Panel
RMT rule making task (EASA)
RNAV area navigation
RNG Range (aeronautics)
RNP required navigation performance
RoC Rate of climb
RoD Rate of descent Or: sink rate
RPA Remotely Piloted Aircraft Or: Unmanned aerial vehicle (UAV)
RPAS Remotely Piloted Aircraft System
RPL Recreational Pilot Licence
RPL repetitive flight planning
RPM Revolutions per minute
RPT regular public transport
RQR Required
RSA runway safety area
RSP Reversion switch panel
RSR en-route surveillance radar
RT radiotelephony
RTB return to base
RTE Route
RTF radiotelephony
RTL rudder travel limiting
RTO Rejected takeoff
RTOL Reduced take-off and landing
RTOW regulatory take-off weight
RVDT rotary variable differential transformer In a turbine engine
RVR runway visual range
RVSM reduced vertical separation minima
RW ramp weight
RWY runway
RX Radio receiver

S

Abbreviation Term Notes
SAF Sustainable aviation fuel
SAIL Specific assurance and integrity level
SAR Search and rescue
SAR Smart ACMS Recorder
SAR Surveillance Approach Radar
SAS stability augmentation system
SAT Static Air Temperature Or: Outside air temperature (OAT)
SATCOM Satellite communication
SATNAV Satellite navigation
SB service bulletin
SBAAS Satellite-Based Augmentation System Or: SBAS
SC special condition
SCAP Standard Computerized Airplane Performance
SCCM senior cabin crew member
SD Secure digital
SDF Simplified directional facility
SDU Satellite data unit
SELCAL Selective calling
SEP Safety and Emergency Procedures
SEP single-engine piston
SESAR Single European Sky ATM Research
SESMA Special Event Search and Master Analysis
SF Stratus Fractus Cloud type
SFCC Slat Flap Control Computer
SFO Senior First Officer
SFP Short Field Performance B737 Enhancement program for landing in short runways
SFOC Special Flight Operating Certificate
SID standard instrument departure
SIGMET Significant Meteorological Information
SIU Satellite interface unit
SLPC single lever power control
SM service manual
SMM safety management document ICAO
SMOH Since major overhaul
SMR surface movement radar
SMS Short Messaging Service
SMT software maintenance tool
SN serial number
SNR signal-to-noise ratio
SOC start of climb at missed approach
SODPRO simultaneous opposite direction parallel runway operations
SOF special operations forces Military unit
SOG speed over ground Same as ground speed
SOG Special Operations Group
SOP standard operating procedure
SOW Statement of Work
SPKR Speaker
SPS Stall Protection System
SQ Squelch Or: SQL
SR sunrise
SRM structural repair manual
SRS Speed Reference System
SS sunset
SSCV/DR Solid-state cockpit voice/data recorder See flight recorder
SSCVR Solid-state cockpit voice recorder See flight recorder
SSFDR Solid-state flight data recorder See flight 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
STOL short take-off and landing[1]
STP Standard temperature and pressure
STS speed trim system
SUA Special use airspace
SVFR Special visual flight rules
SVGS Synthetic vision guidance system

T

Abbreviation Term Notes
TA traffic advisory See TCAS
TAA terminal arrival altitude
TAA terminal arrival area
TAC thrust asymmetry compensation
TACAN tactical air navigation (system)
Tach Tachometer
TAD Terrain awareness display
TAF terminal aerodrome forecast Or: Terminal area forecast.
TAI thermal anti-ice
TALPA Takeoff and Landing Performance Assessment Aviation Rules Committee
TAM total airport management
TAR terminal approach radar
TAS true airspeed
TAT total air temperature Or: true air temperature
TAWS terrain awareness and warning system
TBO time between overhauls Or: time before overhaul
TBV transient bleed valve In turbine engines
TC Transport Canada
TC towering cumulus
TC turn coordinator
TC True Course
TC type certificate
TCA terminal control area (USA/Canada) Europe: terminal manoeuvring area (TMA)
TCA Throttle control assembly
TCAS traffic collision avoidance system
TCCA Transport Canada's Civil Aviation
TCDS type certificate data sheet
TCF Terrain clearance floor
TCH threshold crossing height
TCI thrust computer indicator
TCN TACAN
TCU Telecommunication control unit Or: terminal control unit, or line control unit, used in Air traffic control
TDOP Time dilution of precision
TDR Transponder (In some cases)
TDZ touchdown zone
TERPS terminal instrument procedures Or: terminal en route procedures
TFC traffic
TFR temporary flight restriction Airspace
TFT Thin-film transistor
TGB transfer gearbox
TGL temporary guidance leaflet
TGL(S) touch-and-go landing(s)
TGT Target
TGT Turbine gas temperature
THLD threshold Or: THR
TH True Heading Or: THDG
THR runway threshold
THS trimmable horizontal stabilizer, see tailplane
TIS–B Traffic information service – broadcast
TIT turbine inlet temperature
TK Track angle
TKE Track-angle error
TLD time-limited dispatch
TLA Three-letter acronym
TLA Thrust lever angle
TLB technical logbook (EASA)
TLS transponder landing system
TMA terminal manoeuvring area (Europe) USA/Canada: terminal control area
TMG touring motor glider
TML Toolbox Mobile Library (Boeing)
TMZ transponder mandatory zone
TOC Top of climb Or: T/C
TOD top of descent (point) Or: T/D
TODA take-off distance available
TO/GA Takeoff/go-around switch / thrust Or: TOGA
TOP take-off power
TOR take-off runway
TORA take-off runway available
TOT Turbine outlet temperature
TOW take-off weight
TOWS take-off warning system
TR tail rotor Or: T/R. Helicopters.
TR thrust reverser(s) Or: T/R
TR transformer rectifier
TR transmitter receiver or transceiver Or: T/R
TP turning point at missed approach
TRA temporary reserved area (airspace)
TRACON terminal radar approach control
TRANS transition
TRANS Transmission (telecommunications) Or: transmit
TRE type rating examiner
TRK Track
TRP thrust rating panel
TRP Mode S transponder
TSO technical standard order[2] FAA specification of quality standard.
TSLOVH Time since last overhaul Normally measured in FH or EFH
TSN Time since new Normally measured in FH or EFH for an aircraft, engine or component
TTAF total time air frame
TTL Tuned to Localizer
TTR TCAS II transmitter/receiver
TTS Time to station
TTSN total time since new
TTSO total time since overhaul
TVE Total vertical error
TWB Transcribed Weather Broadcasts[6] Abbreviated area forecast
TWC tail wind component
TWDL Two-way data link Or: terminal weather data link
TWDR Terminal Doppler Weather Radar
TWIP Terminal weather information for pilots
TWLU Terminal Wireless LAN Unit
TWR Air traffic control tower
TWR Terminal weather radar
TWY taxiway
TX Transmit

U

Abbreviation Term Notes
UAC Upper area control
UART Universal asynchronous receiver-transmitter
UAS Unmanned Aircraft System[20]
UAV Unmanned aerial vehicle Commonly called 'drones', also 'Remotely Piloted Aircraft (RPA)'
UHF ultra-high frequency
UIR upper information region
ULB underwater locator beacon
UNICOM Universal Communications, air-ground communication facility
UNL Unlimited Seen on GFA and is used for visibility
UPRT upset prevention and recovery training
USB Universal Serial Bus
UTC Universal Time Coordinated Indicates time zones

V

Abbreviation Term Notes
V magnetic variation
V Volts or voltage
V&V video & vision[21]
VAR Variation
VASI visual approach slope indicator VASIS = visual approach slope indicator system
VBV variable bleed valve In turbine engines
VCR visual control room
VCS vehicle control service
VDF VHF direction-finding
VDL VHF Data Link
VDP visual descent point Point in a direct approach where a 3º normal visual descent can be started to achieve a safe landing and stabilized approach to the RWY - VDP (in distance) = HAT (height over terrain) / 300 (HAT is the height of the MDA read in the approach chart of the AD)
VDR VHF digital radio
VFO Variable-frequency oscillator
VFR visual flight rules
VG vortex generator
VGA Video Graphics Array
VG/DG Vertical gyroscope/directional gyroscope
VGLS Visual Guidance Lighting Systems FAA navigation services
VGM voice generator module See AWOS
VHF very high frequency
VID visible impact damage
VIGV variable inlet guide vane
V/L VOR/Localizer
VMC visual meteorological conditions
VMC minimum control speed with critical engine out
VNAV vertical navigation Or: V/NAV
VNC VFR navigation chart
VNE Never exceed speed
VNO Maximum structural cruising speed
VNR VHF navigation receiver
VOR VHF omni-directional range
VOR/DME VOR with Distance measuring equipment
VOR/MB VOR marker beacon
VORTAC VOR and TACAN combination
VOX Voice transmission Voice Operated Transmitter
VPA Vertical Path Approach
VPATH Vertical path
V/R Voltage regulator
VRP Visual point of reference
VRS vortex ring state Helicopter flight phenomenon
V/S Vertical speed
VSCF variable speed constant frequency Electricity generation system
VSI vertical speed indicator
VSM Vertical separation limit
VSO Stall speed in landing configuration
VSV variable stator vane In a turbine engine
VSWR Voltage–standing wave ratio
VTA VFR terminal area chart[1]
VTOL vertical take-off and landing[1]
V/TRK Vertical track
VVI vertical velocity indicator Same as VSI
VX Speed for best angle of climb
VY Speed for best rate of climb

V speeds

Main article: V speeds

W

Abbreviation Term Notes
WAAS Wide Area Augmentation System
WAC World Aeronautical Chart
WAT weight, altitude, temperature Variables that affect takeoff performance
W&B Weight & Balance Sometimes referred to as WxB
WCA Wind Correction Angle
WD Wind direction Or: WINDR
WDM Wiring Diagram Manual
WEF with effect from
WEP War Emergency Power
WL Waterline
WMA WXR waveguide adapter
WMI WXR indicator mount
WMS Wide-area master station
WMSC Weather message switching center
WMSCR Weather message switching center replacement
WOCL window of circadian low
WOFW weight-off-wheels Indicates aircraft is off ground since lift off
WONW weight-on-wheels Indicates aircraft is on ground since touch down
WPT Waypoint Or: WYPT
WRT WXR receiver transmitter
WS wind shear
WTC Wake Turbulence Category
Wx weather[1]
WXR Weather radar system

X

Abbreviation Term Notes
XC cross-country[1]
XCVR Transceiver
XFR Transfer
XMIT transmit
XMSN transmission
XMTR transmitter
XPDR transponder
XPNDR transponder
XTK Crosstrack
X-Start Cross-start Using the air pressure or electrical power from a working engine

Y

Abbreviation Term Notes
Y yaw or yaw angle
Y/D yaw damper Or: YD

Z

Abbreviation Term Notes
Z Zulu Time Coordinated Universal Time (UTC)
ZFT zero-fuel time
ZFW zero-fuel weight

See also

References

  1. ^ a b c d e f g h i j k l m n o p q r s t u v w McDonald, Sandy A.F. From the ground up. Aviation Publishers Co. Ltd. pp. Appendix B.
  2. ^ a b c d e Jeppesen, Boeing. A&P Technician General Textbook. pp. Glossary.
  3. ^ "Definition of ACFT". www.merriam-webster.com. Retrieved 2023-05-11.
  4. ^ FAA Airman Certification Standards
  5. ^ "Chapter 2: Aeronautical Decision-Making". Pilot’s Handbook of Aeronautical Knowledge (PDF). Federal Aviation Authority. November 3, 2023.
  6. ^ a b c d e f g Nielsen, Dane. PILOT PREP. Canuck West Holdings Inc.
  7. ^ "Actual Off-Block Time - EUROCONTROL ATM Lexicon". ext.eurocontrol.int. Retrieved 2019-03-12.
  8. ^ "AWWS – Forecasts and Observations". flightplanning.navcanada.ca. Retrieved 2017-04-06.
  9. ^ "Airworthiness Directives".
  10. ^ "Current rules". 17 February 2016.
  11. ^ Aviation., Canada. Transport Canada. Canada. Civil (2005). Transport Canada aeronautical information manual : (TC AIM). Transport Canada. OCLC 1083332661.
  12. ^ "CNS/ATM Systems" (PDF). International Civil Aviation Organization.
  13. ^ "FAR/AIM Series". Aviation Supplies & Academics, Inc.
  14. ^ "HFE".
  15. ^ Canada, Environment and Climate Change (2012-05-23). "MANAB: Manual of Word Abbreviations - 4th edition". www.canada.ca. Retrieved 2022-09-12.
  16. ^ "Chapter 4: Meaconing, Intrusion, Jamming, and Interference Reporting". Communications Techniques: Electronic Counter-Countermeasures. FM 24-33. United States Department of the Army. July 17, 1990.
  17. ^ Federal Aviation Administration, FAA. "What is a NOTAM?".
  18. ^ "Training requirements". Civil Aviation Authority (UK).
  19. ^ Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 218. ISBN 9780850451634.
  20. ^ US DoD
  21. ^ V&V – thefreedictionary.com

Sources