A – Aeroplane, Alpha(phonetic alphabet), Altimeter(for QNH in Mercury)
AA – Amended
AAAE – American Association of Airport Executives
AAE – Accredited Airport Executive
AAF – Airway Facilities Service
AAI – FAA Office of Accident Investigation
AAIU – Air Accident Investigation Unit
AAL – Above Aerodrome Level
ABn – Aerodrome Beacon
A/C – Aircraft, Airconditioning Unit
Ac(or AC) – Altocumulus
AC – Alternating Current, Advisory Circular
ACAS – Airborne Collision Avoidance System
ACARS – Aircraft Communciations and Addressing and Reporting System
ACC – Area Control Centre
ACI – Airport Council International
ACT – Active or Activated or Activity
AD – Aerodrome/Aerodrome Data, Airworthiness Directive(FAA)
ADA – Advisory Area
ADB – Airports Database
ADC – Air Data Computer
ADELT – Automatically Deployable Emergency Locator Transmitter
ADEXP – ATS Data Exchange
ADIZ – Air Defence Identification Zone
ADF – Automatic Direction Finder
ADI – Attitude Direction Indicator
ADR – Advisory Route
ADS – Automatic Dependent Surveillance
ADT – Approved Departure Time
AES – Aircraft Earth Station
AF – Audio Frequency
AFC – Area Forecast Centre
AFCS – Automatic Flight Control System
A/FD – Airport Facility Directory
AFD – Adaptive Flight Display
AFDS – Autopilot Flight Director System
AFIL – Flight Plan filed in the air
AFIS – Aerodrome Flight Information Service
AFISO – Aerodrome Flight Information Service Officer
AFM – Aeroplane Flight Manual
AFS – Aeronautical Fixed Service, Aerodrome Fire Service
AFTN – Aeronautical Fixed Telecommunications Network
AG – Arrester Gear
A/G – Air/Ground Radio Station
AGA – Aerodrome Ground Aid
AGL – Above Ground Level
AHRS – Attitude-Heading Reference System
AI – Attitude Indicator (Artificial Horizon)
AIAA – Area of Intense Aerial Activity
AIB – Aerodrome Information Bulletin
AIC – Aeronautical Information Circular
AIP – Aeronautical Information Publication, (GEN) General, (ENR) EN Route (AD) AeroDrome
AIRAC – Aeronautical Information Regulation And Control
AIREP – Air Report
AIRMET – Aircraft Meteorological Service
AIRPROX – Aircraft Proximity (near miss) AIS – Aeronautical Information Services
ALT – Altimeter, Altitude
ALTN – Alternate
AM – Amplitude Modulation
AMC – Acceptable Means of Compliance, Aeromedical Centre
AMD – Amended
AME – Authorised/Aeronautical/Aviation Medical Examiner
amps – Amperes
AMLCD – Active-Matrix Liquid Crystal Display
AMSL – Above Mean Sea Level
ANDS – Acceleration apparent turn North, Deceleration apparent turn South
ANGR – Air Navigation General Requirements
ANM – Air Nautical Mile
ANO – Air Navigation Order
ANR – Air Navigation Regulation
ANS – Active Noise System
ANT – Antenna
AoA – Angle of Attack
AO – Aircraft Operator
AOC – Aircraft Owner’s Certificate
AOG – Aircraft on Ground
AOPA – Aircraft Owner’s and Pilot’s Association
AOR-E – Atlantic Ocean Region East
A & P – Airframe and Powerplant
AP – Airport, Autopilot, Approach
APP – Approach Control
APCH – Approach
APR – Auxiliary Power Reserve
APT – Attitude, Power, Trim
APU – Auxiliary Power Unit
ARFOR – Area Forecast
ARINC – Aeronautical Radio Incorporated
ARMET – Forecast upper wind and temperature at specified points
ARN – ATS Route Network
ARR – Arrival
ARTAS – ATM Surveillance Tracker and Server
ARTIFAX – Facsimile Broadcast Service
As(or AS) – Altostratus
ASA – Autoland Status Annuniciator
ASAP – As Soon As Possible
ASCB – Avionics Standard Communication Bus
ASDA – Accelerate-Stop Distance Available
ASI – Airspeed Indicator
ASL – Above Sea Level
ASM – Airspace Management
ASR – Altimeter Setting Regions, Approach Surveillance Radar
AT – At(weather)
A/T – Auto Throttle
ATA – Aerial Tactics Areas, Actual Time of Arrival
ATAS – Air Traffic Advisory Service
ATC – Air Traffic Control
ATCC – Air Traffic Control Centre
ATCO – Air Traffic Control Officer
ATD – Actual Time of Departure
ATE – Actual Time Enroute
ATFM – Air Traffic Flow Management
ATIS – Air Traffic Information Service
ATM – Air Traffic Management
ATMC – Air TRaffic Managment Centre
ATN – Aeronautical Telecommunications Network
ATP – Airline Transport Pilot
ATPL – Air Transport Pilot License
ATS – Air Traffic Service
ATSU – Air Traffic Service Unit
ATTN – Attention
ATZ – Aerodrome Traffic Zones
AUW – All-Up Weight
AUX – Auxiliary
AVGAS – Aviation Gasoline (100LL – Low Lead)
AVTUR – Aviation Turbine Fuel[kerosene] (same as JetA1)
AWACS – Airborne Warning And Control System
AWY – Airway
AZM – Azimuth


B – Bravo(phonetic alphabet), Blue
BAA – British Airports Authority
BALPA – British Airline Pilot’s Association
BASE – Cloudbase
BBAC – British Balloon and Airships’ Club
BC – Patches(of cloud)
BCAR – British Civil Airworthiness Requirements
BCD – Binary Coded Decimal
BCF – BromoChloridiFluoromethane (Halon Fire Extinguisher)
BCN – Beacon
BCP – Break Cloud Procedures
BCPL – Basic Commercial Pilot’s License
BCST – Broadcast
BDC – Bottom Dead Centre
BDRY – Boundary
BECMG – Becoming
BFO – Beat Frequency Oscillator, Blazing Flash of the Obvious
BFR – Biennial Flight Review(USA)
BHP – Brake Horsepower
BITE – Built-In Test Equipment
BKN – Broken
BL – BLowing
BLO – BeLOw clouds
BOW – Basic Operating Weight
BPPL – Basic Private Pilots License
BR – Mist
BRG – Bearing
BRITE – Bright Radar Indicator Tower Equipment
BRL – Building Restriction Lines
B-RNAV – Basic Area Navigation
BS – Commercial Broadcasting Station
BSU – Beam Steering Unit
BT – Basic Transport
BTN – BeTweeN
BTU – British Thermal Unit
BU – Basic Utility
BUMFICH – Brakes, Undercarriage, Mixture, Fuel & Flaps, Instruments, Carb Heat, Hatches & Harnesses(Downwind Check)
BUEC – Backup Emergency Communications


C – Charlie(phonetic alphabet), Celsius

CA – Closing Angle, Conflict Alert
CAA – Civil Aviation Authority, Civil Aeronautics Administration (or Authority)
CAB – Civil Aeronautics Board
CAIRDE – Civil Aviation Integrated Radar Display Equipment
CAMI – Civil Aeronautics Medical Institute
CANP – Low-Level Civil Aircraft Notification Procedure
CANSO – Civil Air Navigation Services Organisation
CAP – Civil Aviation Publication, Civil Air Patrol
CARB – Carburetor
CARF – Central Altitude Reservation Function
CAS – Calibrated Airspeed, Controlled Airspace
CASA – Computer-Assisted Slot Allocation
CAT – Clear Air Turbulence, Category, Commercial Air Transport/Traffic
CATI – Category I ILS (uses MALSR) CATII – Catgory II ILS (uses ALSF-2) CATIII – Category III ILS (uses ALSF-2) CAVOK – Ceiling And Visibility OK(weather)
CAVU – Ceiling And Visibility Unlimited
Cb(or CB) – Cumulonimbus
CB – Circuit Breaker
CBD – Central Business District
Cc(or CC) – Cirrocumulus
CC – Correction(weather)
CCC – Crew Coordination Concept
CCM – Chemically Correct Mixture
CD – Clearance Delivery, Coefficient of Drag(also Cdrag)
CDA – Continuous Descent Approach
CDI – Course Deviation Indicator
CDT – Controlled Departure Time
CDTI – Cockpit Display of Traffic Information
CDU – Control Display Unit
CE – Categorical Exclusion, Certificate of Engineering
CEPHACER – Callsign & Type, En Route, Position, Heading, Altitude, Conditions, Estimate, Request(if applicable)
CFI – Certified Flying Instructor
CFII – Certified Flying Instructor Instrument
CFIT – Controlled Flight Into Terrain
CFR – Code of Federal Regulations, Crash Fire Rescue
CFS – Cubic Feet per Second
CFW – Center Field Wind
CFWSU – Central Flow Weather Services Unit
CG – Centre of Gravity
CGI – Chief(or certified) Ground Instructor
CH – Compass Heading
CheckA – Daily Inspection
CHiRP – Confidential Human Factor’s Reporting Programme
CHT – Cylinder Head Temperature
Ci(or CI) – Cirrus
CIC – Controller In Charge
CIP – Capital Investment Plan
CIR – CIRcuit flight operation
CIV – Civil
CL – Centerline lights, Coefficient of Lift(also Clift)
Cliftmax – Maximum Coefficient of Lift
CLD – Cloud
CLSD – Closed
CLUZ – Compatible Land Use Zones
CMA – Calcium Magnesium Acetate
CMATZ – Combined Military Aerodrome Traffic Zone
CMOS – Complementary Metal Oxide Semiconductor
CMU – Communications Management Unit
CNIPI – Callsign & Type, Nature of Emergency, Intention, Position, Information(anyhting else pertinent)
CNR – Composite Noise Rating
CNS – Continuous, Communications Navigation & Surveillance
CofA – Certificate of Airworthiness
CofE – Certificate of Experience
COM – Communications
CofT – Certificate of Test
COT – CoasTaL
CP – Centre of Pressure
CPA – Closest Point of Approach
CPL – Commercial Pilot License
CQB – Central Question Bank
CR – Class Rating
C/R – Counter-Rotating Propeller
CRAF – Civil Rescue Air Fleet
CRDA – Converging Runway Display Aid
CRE – Class Rating Examiner
CRI – Class Rating Instructor
CRM – Cockpit Resource Management
CRP – Compulspry Reporting Point
CRS – Crash Rescue Service
CRT – Cathode Ray Tube
C/S – Callsign
Cs(or CS) – Cirrostratus
CSDB – Commercial Standard Data Bus
CSS – Checkpoint Security Supervisors
CSU – Constant Speed Unit
CTA – Control Area, Controlled Time of Arrival
CTAF – Common Traffic Advisory Frequency
CTL – Control
CTN – Caution
CTR – Control Zone
Cu(or CU) – Cumulus
CUF – Cumuliform
CUST – Customs
CVR – Cockpit Voice Recorder
CW – Carrier Wave, Continuous Wave
CWA – Centre Weather Advisory
CWSU – Centre Weather Services Unit
CY – Cubic Yards
CZ – Control Zone


D -Delta(phonetic alphabet), Decreasing, Drag, Danger Area, Day
D&D – Distress and Diversion
DA – Decision Altitude, Density Altitude, Drift Angle
DAAIS – Danger Area Activity Information Service
DACS – Danger Area Crossing Service
DADC – Digital Air-Data Computer
DA(H) – DA & DH (Jeppesen approach charts)
DALR – Dry Adiabatic Lapse Rate
dB – Decibel
dBA – Decibels on the A Weighted
DC – Direct Current, Dual Control
D/C – Demand/Capacity Radio DCIA – Dependent Converging Instrument Approaches
DCT – Direct
DECR – Decrease/Decreasing
DEDS – Data Entry Display System
DEG – Degrees
DEIS – Draft Environmental Impact Statement
DEL – Delay/Delayed
DEP – Departure
DEST- Destination
DEV – Deviation
DF – Direction Finding
DFM – Departure Flow Management
DG – Directional Gyro(HI)
DGPS – Differential Global Positioning System – (LA) – Local Area (WA) – Wide Area
DH – Decision Height, Density Height
DI – Direction Indicator(HI), Daily Inspection
DIR – Director
DIST – Distance
DME – Distance Measuring Equipment
DNG – Danger or Dangerous
DNL – Day Night average sound Level(also Ldn)
DOC – Designated Operational Coverage
DOF – Date of Flight
DOP – Dilution of Precision
DP – Dewpoint Temperature, Deal Pending
DR – Dead Reckoning or Low Drifting(weather)
drms – Distance Root Mean Squared
DS – Duststorm
DSP – Departure Spacing Program
DTAM – Descend to and Maintain
DTK – Desired Track
DTRT – Deteriorate/Deteriorating
DTU – Data Transfer Unit
DU – Widespread Duststorm
DZ – Drizzle, Dropping Zone


E – Echo(phonetic alphabet), East
EA – Environmental Assessment
EAA – Experiemtal Aviation Authority
EAC – Expect Approach Clearance
EADI – Electrinic Altitude Director Indicator
EAS – Essential Air Service
EASA – European Aviation Safety Authority
EAT – Expected Approach Time
EATCHIP – European Air Traffic Control Harmonisation and Integration Programme
ECAC – European Civil Aviation Conference
ECAM – Electronic Centralised Aircraft Monitoring
ECOGAS – European Council of General Aviation Support
ECU – Environmental Control Unit
ED – Emergency Distance
EDCT – Expect Departure Clearance Time
E/E – Entry/Exit Lane
EET – Estimated Elapsed Time
EFAS – En-Route Flight Advisory Service, Electronic Flash Approach Light System
EFATO – Engine Failure At(or After) Take-Off
EFF – EFFective
EFIS – Electronic Flight Instrument Systems
EFM – En-Route Flow Management
EGT – Exhaust Gas Temperature
EHSI -Electronic Horizontal Situation Indicator
EIAR – Environmental Impact Assessment Report
EICAS – Engine Indicating and Crew Alerting System
EIR – Environmental Impact Report
EIS – Environmental Impact Statement
ELB – Emergency Locator Beacon
ELB-A – Emergency Locator Beacon – Aircraft
ELEV – Elevation
ELT – Emergency Locator Transmitter
ELR – Environmental Lapse Rate
EMBD – Embedded
EMERG – Emergency
ENE – East-Northeast
ENRT – En Route
EOF – Emergency Operations Facility
EOBT – Estimated Off-Block Time
EPA – Environmental Protection Agency
EPIRB – Emergency Position Indicating Radio Beacon
EPNdB – Effective Perceived Noise Decibel
EPNL – Effective Perceived Tone-Corrected Noise Decibel
epr – Engine Pressure Ratio
ERA – European Regional Airlines Association
ESE – East-Southeast
ESP – En-Route Spacing Program
EST – Estimate
ETA – Estimated Time of Arrival
ETD – Estimated Time of Departure
ETE – Estimated Time En-Route
ETI – Estimated Time Interval
ETMS – Enhanced Traffic Management System
ETN – Electronic Tandem Network
ETOPS – Extended Range Twin-Engine Operations(engines turn or passengers) EVCS – Electronic Voice Communications System
EVFR – Electronic Visual Fight Rules


F – Foxtrot(phonetic alphabet), Fahrenheit
FAA – Federal Aviation Administration (or Authority)
FAC – Facilities
FADEC – Full Authority Digital Engine Control
FAF – Final Approach Fix
FAL – Facilitation of International Air Transport
FAP – Final Approach Point
FAR – Federal Aviation Regulation
FAST -Final Approach Spacing Tool
FAT – Final Approach Track
FAWP – Final Approach Waypoint
FBO – Fixed Base Operator
FBU – Flight Briefing Unit
FBW – Fly-By-Wire
FC – Funnel Cloud(tornado or water-spout)
FCC – Federal Communications Commission (what Slim Shady refers to, I think) FCL – Flight Crew Licensing
FCM – Flight Confirmation Message
FCST -Forecast
FCU – Fuel Control Unit
FD – Flight Director
FDE – Fault Detection & Exclusion(GPS)
FDI – Flight Director Indicator
FDIO – Flight Data Input/Output
FDPS – Flight Data Processing System
FDR – Flight Data Recorder
FDS – Flight Director System
F&E – Facilities And Equipment
FE – Flight Examiner
FEIS – Final Environmental Impact Statement
FEMA – Federal Emergency Management Agency
FEW – Few Clouds
FF – Federal Finding
FFON – Flight Phone
FG -Fog
FI – Flight Instructor, Flight Identity(Mode S XPDR)
FIC – Flight Information Centre
FIE – Flight Instructor Examiner
FIR – Flight Information Region
FIS – Flight Information Service
FISA – Automated Flight Information Service (see also AFIS) FISO – Flight Information Service Officer
FL – Flight Level
FLIR – Forward-Looking Infra-Red
FLT – Flight(s)
FLTCK – Flight Check
FLUC – Fluctuating
FM – From(Weather), Frequency Modulation
FMA – Final Monitor Aid
FMCS – Flight Management Computer System
FMS – Flight Management System
FNPT – Flight and Navigation Procedures Trainer
FO – Forested Land
FOD – Foreign Object Damage
FOG – Fibre-Optic Gyro
FONSI – Finding of No Significant Impact
FPL – Full Performance Level, Flight Plan
FPM – Feet Per Minute
FPT – Flight Planned Track
FREH(D)A – Fuel, Radio, Engine, Heading(Direction), Altitude
FREQ – Frequency
FRQ – Frequent
FRTO(L) – Flight Radiotelephony Operator’s License
FS – Flight Simulator
FSM – Flight Schedule Monitor
FSS – Flight Service Station
ft – Feet
FTD – Flight Training Device
ft/min – Feet Per Minute
FTO -Flying/Flight Training Organisation
FU – Smoke
FUA – Flexible Use Airspace
FW – Flight Watch
FWCS – Flight Watch Control Station
FZ – Freezing


G – Gusting, Golf(phonetic alphabet), Acceleration Force Unit, Green
GA – General Aviation
GA/AW – General Aviation/Aerial Work GAPAN – Guild of Air Pilots and Navigators
GAL – Gallons (US 3.78 litres, may be Imperial 4.54 liters) GAT – General Air Traffic
GC – Great Circle, Ground Control
GCA – Ground Controlled Approach
GCR – Ground Clutter Rejection
GDE – Ground Delay Enhancements
GEN – Generally(weather)
GEO – Geostationary Earth Orbit
GFT – General Flight Test
GLD – Glider
GLS – GPS Landing System
GLU – GNSS Landing Unit(CATIII)
GMC – Ground Movement Control
GMP – Ground Movement Planning
GMT – Greenwich Mean Time(now UTC)
GN – Green
GND – Ground
GNSS – Global Navigation Satellite System
GP – Glidepath
GPADIRS – Global Positioning Air Data Inertial Reference System
gph – Gallons Per Hour
GPS – Global Positioning System
GPU – Ground Power Unit
GPWS – Ground Proximity Warning System
GR – Hail, General Transport
GRADU – Gradual or Gradually
GS – Ground Speed, Glide Slope or Small Hail and/or snow pellets
G/S – Glideslope Receiver & Indicator
GSM – General Standard for Mobile Communications
GTOW – Gross Take-off Weight
GU – General Utility
GUMPS – Gas, Undercarriage, Mixture, Prop, Seatbelt
GVS – Gas Venting Site
GW – Gross Weight
GWDS – Graphic Weather Display System


H – High(Weather), Helicopter, Hotel(phonetic alphabet)
H24 – 24 Hours
HAA – Historic Aircraft Association
HAI – Helicopter Association International
HASELL – Height, Airframe, Security, Engine, Location Satisfactory, Look Out
HAT – Height Above Threshold(Jeppesen Approach Charts) HAZ MAT – Hazardous Materials
HBN – Hazard Beacon
HC – Hydrocarbons
HDG(C) – Heading Compass, actual heading on compass
HDG(M) – Heading Magnetic
HDT(T) – Heading True
HEL – Helicopter
HELPME – HEMS – Helicopter Emergency Medical Services
HEO – High-Earth Orbit
HF – High Frequency
Hg – Inches of Mercury(USA unit of atmospheric pressure)
HGT – Height or Height Above
HI – Heading Indicator
HIAL – High-Intensity Approach Lighting
HIGE – Hover In Ground Effect
HIRF – High-Intensity Radiated Fields
HIRL – High-Intensity Runway Lighting
HIRTA – High Intensity Radio Transmission Area
HISL – High-Intensity Strobe Lighting
HJ – Hours Jour(Day) i.e. Sunrise to Sunset
HLDG – Holding
HMI – Human Machine Interface
Hmr – Homer
HN – Hours Night i.e. Sunset to Sunrise
HNM – Helicopter Noise Model
HO – Hours of Operational Requirement
HOGE – Hover Out of Ground Effect
HOTAS – Hands on Throttle and Stick
HP – Horsepower, Holding Point
HPa – Hectopascal
HPA – High-Power Amplifier
HR – Hours
HS – Hours Scheduled i.e. During Scheduled Operations
HSI – Horizontal Situation Indicator
HT – Head of Training
HTA – Helicopter Training Area
HUD – Head-Up Display
HVY – Heavy
HX – Operating hours on request, no specific working hours
HZ – Dust Haze


I – Indigo(phonetic alphabet)
IAA – Irish Aviation Authority
IAC – Integrated Avionics Computer, Irish Aer Corps
IAF – Initial Approach Fix
IAP – Instrument Approach Procedure
IAPA – Instrument Approach Procedures Automation
IALPA – Irish Airline Pilot’s Association
IAPS – Integrated Avionics Processing System
IAS – Indicated Airspeed
IATA – International Air Transport Association
IATSC – International Telecommunications Switching Centre
IAWP – Initial Approach Waypoint
IBn – Identification Beacon
I/C – Intercom IC – Ice Crystals
ICAA – International Civil Airports Association
ICAO – International Civil Aviation Organisation
ICE – Icing
ID/IDENT – Identification
IEM – Interpretative and Explanatory Manual
IF – Instrument Flying, Intermediate Approach Fix
IFR – Instrument Flight Rules
IFSS – International Flight Service Station
IG – Imperial Gallon
IGE – In Ground Effect
IGPH – Imperial Gallons Per Hour
IGS – Instrument Guidance System
ILS – Instrument Landing System
IM – Inner Marker
IMF – Internal Flow Management
IMC – Instrument Meteorological Conditions
IMES – Irish Marine Emergency Service
IMPR – Improving
IMSAFE – Illness, Medication, Stress, Alcohol, Fatigue, Emotion
IMT Immediately
in – inches (in aviation of mercury – unit of atmospheric pressure) INC – In Cloud
INCR – Increase/Increasing
INFO – Information
INOP – Inoperative
INS – Inertial Navigation System
INT – Intersection take-off, Interior
INTER – Intermittent(see TEMPO) INTSF – Intensify/Intensifying
IOAT – Indicated Outside Air Temperature
IOT – Input/Output Terminal
IPG – IFR Procedure Group
IR – Instrument Rating, Ice on Runway, Infra-Red
IRE – Instrument Rating Examiner
IRI – Instrument Rating Instructor
IRVR – Instrumented Runway Visual Range
ISA – International Standard Atmosphere
ISOL – Isolated
ISWL – Isolated Single Wheel Load
ITC – In-Trail Climb
ITD – In-Trail Descent
ITU – International Telephone Union(HF COM)
IU – Index Unit
IVSI – Instantaneous Vertical Speed Indicator


J – Juliet(phonetic alphabet)
JAA – Joint Aviation Authority
JAR – Joint Aviation Regulations/Recommendations/Requirement
JATO – Jet Assisted Take-Off
JB – Jet Barrier
JETA1 – Jet Turbine Fuel (same as AVTUR) JPATS – Joint Primary Aircraft Training System
JSA – Joint Steering Assembly
JURG – Joint User Requirement Group


K – Kilo(phonetic alphabet)
KCAS – Calibrated Airspeed (Knots)
Kg – Kilograms
kHz – Kilohertz(unit of frequency) KIAS – Indicated Airspeed (Knots)
km – Kilometre(unit of distance) KMH – Kilometres per hour
kPa – Kilopascal
KPAs – Key Performance Areas
kph – Kilometres Per Hour
KPI – Key Performance Indicator
KRAS – Rectified Airspeed (Knots)
kt – Knot(unit of speed, 1.852km/h)
KTAS – Knots True Air Speed
kw – Kilowatt


L – Low (Weather), Lima(phonetic alphabet), Lift, Locator, Left
LAHSO – Land and Hold Short Operation
LAMAX – A-Level Maximum (noise metric)
LAMS – Light Aircraft Maintenance Schedule
LAN – Inland
LARS – Lower Airspace Radar Service
LAT – Latitude
LATCC – London Air Traffic Control Centre
LAWRS – Limited Aviation Weather Reporting Station
LC – Local Control
LCD – Liquid Crystal Display
Lctr – Locator Beacon(NDB)
LD – Landing Distance
L:D – Lift/Drag Ratio(also L/D)
LDA – Landing Distance Available, Localizer Directional Aid
LDG – Landing
LDIN – Lead-In LIghts
LDN – Day-Night Average Sound Level(also DNL)
LEO – Low-Earth Orbit
LEPN – Symbol for EPNL – perceived sound exposure level(dB)
LEQ – Equivalent Sound Level
LF – Low Frequency
LFA – Local Flying Area
LGT – Light/Lighting
LH – Left-Hand
LIRL – Low-Intensity Runway Lights
LIRS – Low-Impact Resistance Supports
LITAS – Low-Intensity Two-Colour Approach System
LLZ – Localizer
LLWAS – Low-Level Windshear Alert System
LMB – Light Marker Beacon
LMT – Local Mean Time
LNAV – Lateral Navigation(GLS)
LOA, LoA – Letter of Agreement
LOC – Location, Locally, Localizer
LOFT – Line-Oriented Flight Training
LOM – Locator Outer Marker
LONG – Longitude
LoP – Line of Position
LORAN – Long-Range Air Navigation System
LRR – Long-Range Radar
LRT – Long-Range Fuel Tanks
LRU – Line Replaceable Unit
LSQ – Line Squall
LTFC – Landing Traffic
LT – Local Time
LTE – Long-Term Exception
LTO – Landing and Take-Off cycle
LUG – Land Use Guidance
LV – Light and Variable(wind)
LW – Landing Weight
LYR – Layer/Layered


M – Mike(phonetic alphabet), Minus, Magnetic, Metres
MAD – Mean Aerodynamic Chord
MAHWP – Missed Approach Holding Waypoint
MALS – Medium-Intensity Approach Lighting System
MALSF – Medium-Intensity Approach Lighting System with sequenced Flashers
MALSR – Medium-Intensity Approach Lighting System with Runway alignment indicator lighting system
MAP – Missed Approach Procedure/Point, Manifold Pressure, Aeronautical Maps/Charts
MAPT – Missed Approach Point
MARAS – Middle Airspace Radar Advisory Service
MATSE – Meeting(ECAC Ministers) on the Air Traffic System in Europe
MATZ – Military Aerodrome Traffic Zone
MAUW – Maximum All-Up Weight
MAWP – Missed Approach Waypoint
mb – Millibars
MBRW – Maximum Brake Release Weight
MCA – Magnesium Calcium Acetate
MCC – Multi-Crew Cooperation/Certificate
MCI – Mobile Communication Infrastructure
MCP – Maximum Continuous Power
MCTR – Military Control Zone
MCU – Minimum Configuration Unit
MDA – Minimum Descent Altitude
MDA(H) – Combination of MDA & MDH(Jeppesen Approach Charts)
MDAU – Maintenance Data Acquistion Unit
MDH – Minimum Descent Height, Major Damage History
ME – Multi-Engine
MEA – Minimum En-Route IFR Altitude
MEDA – Military Emergency Diversion Airfield
MEF – Maximum Elevation Figures
MEHT – Minimum Eye-Height over Threshold(VASI/PAPI)
MEL – Minimum Equipment List
MEO – Medium Earth Orbit
MEP -Multi-Engine Piston
MET – Multi-Engine Turboprop, Meteorology(ical)
METAR – METeorological Actual Reports(current weather)
METFAX – METeorological Faxing Service
METO – Maximum Except for Take-Off
MF – Medium Frequency
MFA – Military Flying Area
MFD – Multi-Function Display
MGD – Million Gallons per Day
MGW – Maximum Gross Weight
MH – Magnetic Heading
MHA – Minimum Holding Altitude
MHz – Megahertz
MI – Shallow
MIL – Military
MINIT – Minutes-In-Trail
MIRL – Medium-Intensity Runway LIghts
MIS – Meteorlogical Impact Statement
MIST – Meteorological Information Self-briefing Terminal
MIT – Miles-In-Trail
MKR – Marker radio beacon
MLS – Microwave Landing System
MLW – Maximum Landing Weight
MM- Middle Marker
MMI – Man-Machine Interface(see HMI)
MMR – Multi-Mode Receiver
MN – Magnetic North
MNM – Minimum
MNPS – Minimum Navigational Performance Specifications
MOA – Military Operations Area
MOCA – Minimum Obstacle Clearance System
MOD – Moderate
MOGAS – Motor Gasoline (not same as used in cars etc.)
MOH – Major Overhaul
MON – Motor Octane Number(aviation fuel rating)
MOPS – Minimum Operational Performance Standard(RTCA)
MOS – Military Operations Specialist
MOTNE – Meteorological Operational Telecommunications Network Europe
MP – Manifold Pressure, Multi-Pilot
MPA – Multi-Pilot Aeroplane, Man-Powered Aircraft
mph – Miles Per Hour
MPH – Multi-Pilot Helicopter
MRO – Maintenance, Repair & Overhaul
MRVA – Minimum Radar Vector Altitude
MRW – Maximum Ramp Weight
MS – Minus
MSA – Minimum Safe Altitude, Minimum Sector Altitude(Jeppesen Approach Charts)
MSG – Message
MSP – Maintenance Service Program
MT – Mountain, Magnetic Track
MTBF – Mean Time Between Failures
MTI – Moving Target Indicator
MTMA – Military Terminal Control Area
MTOM – Maximum Take-Off Mass
MTOW – Maximum Take-Off Weight
MTW – Mountain Waves
MTWA – Maximum Total Weight Authorised(AAIU)
MVA – Minimum Vectoring Altitude
MZFW – Maximum Zero Fuel Weight


N – November(phonetic alphabet), No Change, North, Night
NAA – National Aviation Authority(generic term inside JAA)
NADP – Noise Abatement Departure Profile
NAS – National Airspace System
NAT – North Atlantic Track
NATS – National Air Traffic Service(UK)
NAV – Navigation
NAVAID – Navigation Aid
NC – No Change
NDB – Non-Directional Beacon
NDB(L) – NDB(Localizer)
NE – Northeast
NEF – Noise Exposure Forecast
NEM – Noise Exposure Map
NEXRAD – Next Generation Radar
NGT – Night
NIL – Nothing, No Information
NIMBY – Not In My Back Yard
NIPAH – Name, Intentions, Position, Altitude, Heading(Mayday Call) NLR – Noise Level Reduction
NM – Nautical Miles
NMS – Navigation Management System
NMU – Navigation Management Unit
NNE – North-Northeast
NNW – North-Northwest
NO2 – National Oceanic Service
NOAA – National Oceanic and Atmospheric Administration
NOE – Nap of Earth
NORAD – North American Aerospace Defense Command
NORDO – No Radio
NOSIG – No Significant Change
NOTAM – Notices to Airmen
NOTAMC – Cancelled Notices to Airmen
NOTAMN – New Notices to Airmen
NOTAMR – Replaced Notices to Airmen
NOTAR – No Tail Rotor
NOX – Nitrogen Oxide
NPA – Non-Precision Approach, Notice of Proposed Amendment
NPD – Noise-Power-Distance
NPO – Non-Profit Organisation
NPPL – National Private Pilot’s License
NPRL – No Parallel
NPRM – Notice of Proposed Rule Making(USA)
Ns(or NS) – Nimbostratus
NSC – No Significant Cloud
NSW – Nil Significant Weather
NTSB – National Transportation Safety Board(USA)
NTZ – No Transgression Zone
NVM – Non-Volatile Memory
NW – Northwest
NWS – National Weather Service


O – Oscar(phonetic alphabet)
O&D – Origination and Destination
O&M – Operations and Maintenance
OAC – Oceanic Area Control Unit
OAG – Official Airline Guide
OALT – Operational Acceptable Levels of traffic
OAT – Outside Air Temperature, Operational Air Traffic(MIL)
OBI – Omni Bearing Indicator
OBS – Omni Bearing Selector, Observed
OBSC – Obscured
OBST – Obstacle, Obstruction
OCA – Oceanic Control Area, Obstacle Clearance Altitude
OCA(H) – Combination of OCA & OCH(Jeppesen Approach Charts)
OCH – Obstacle Clearance height
OCL – Obstacle Clearance Limit
OCNL – Occasional
ODALS – Omnidirectional Airport Lighting System
OEM – Original Equipment Manufacturer
OFA – Object-Free Area
OFZ – Object-Free Zone
OH – Overhaul
oktas – unit equivalent to one eighth of the sky(describes cloud cover)
OM – Outer Marker
OML – Operational Multicrew Limitation
OMS – Outer-Marker Substitute(virtual kind of OM)
ONC – Operational Navigational Chart
ONUS – Overshoot on North, Undershoot on South (Southern Hemisphere only)
OPMET – Operational Meteorological(Information)
OPS – Operations, Operating Hours
O/R – On Request
OSL – Operational Safety Pilot Limitation
O/T – Other Times
OTD – Other Training Devices
OVC – Overcast
OVF – Overflight Operation
OXY – Oxygen


P – Papa(phonetic alphabet), Plus, Prohibited Area, Primary Frequency
P’s & T’s – Pressures and Temperatures
PA – Passenger Address
PACE – Program for Airport Capacity Efficiency
PANS – Procedures for Air Navigation Services
PAPIS – Precision Approach Path Indicating System
PAR – Precision Approach Radar PART – Pressure-Altitude Reporting Transponder
PAT – Power, Attitude, Trim
PATSA – Power, Attitude, Trim, Sense, Adjust
PAX – Passengers
PBH – Power By the Hour(Rolls-Royce)
PC – Positive Control(Mooney)
PCL – Pilot Controlled Lighting>(RWY controlled by Microphone)
PCS – Power Conditioning System
PCU – Power Control Unit
PDC – Pre-Departure Clearance
PE – Ice Pellets
PEC – Position Error Correction
PED – Personal Electronic Devices(Walkmans etc.)
PEP – Peak Envelope Power
PERM – Permanent
PF – Pilot Flying
PFA – Popular Flying Association
PFC – Passenger Facility Charge
PHACER – Position, Heading, Altitude, Conditions, Estimate, Request
PHARE – Programme for Harmonisation of ATM Research in EUROCONTROL
PIAC – Peak Instantaneous Aircraft Count
PIC – Pilot In Command
PICUS – Pilot In Command Under Supervision
PIO – Pilot Induced Oscillation
PIREP – Pilot Reports
Pitot – Total Pressure
PL – Position Line
PLN – Flight Plan
PM – Particulate Matter
PMS – Performance Management System (Unless of course you’re female!)
PNdB – Percieved Noise Decibel
PN – Prior Notice
PNF – Pilot Not Flying
PNLTM – Perceived Noise Level Tone-Corrected Maximum
PNR – Prior Notice Required, Point of No Return
PNT – Paint
PO – Dust/Sand Whirls(Dust Devils)
POB – Passengers on Board
POH – Pilot’s Operating Handbook
PPI – Plan Position Indicator
PPL – Private Pilot’s License
PPO – Prior Permission Only
PPR – Prior Permission Required
PR – Partial
PRK – Photo Refractory Keratomy(eye surgery)
PRM – Precision Runway Marker
PROB – Probability Factor
PROV – Provisional
PS – Plus
psi – Pounds per Square Inch
PSN – Position
PTN – Procedure Turn
PTT – Press to Transmit/Talk
PTLE – Position, Time, Level, Estimated time to next position
PUF – Propeller, Pitch, Undercarriage, Flaps
PVT – Private
PY – Spray


Q – Quebec(phonetic alphabet), QNH
QATS – Quality Assurance and Training Specialist
QBI – Compulsory IFR Flight
QDM – Magenetic bearing to a NDB
QDR – Magnetic bearing from a NDB
QFE – Height above aerodrome level (Field Elevation)
QFI – Qualified Flying Instructor
QFU – Magnetic Orientation of Runway
QGH – Ground interpreted let-down procedure using direction-finding equipment
QGO – Airport Closed
QNE – Pressure Height(1013.2 mb or hPa)
QNH – MSL pressure level in the actual atmosphere(ALT gives height AMSL)
QoS – Quality of Service
QTE – True magnetic bearing to a NDB
Qts. – Quarts(oil)


R – Romeo(phonetic alphabet), Runway, Restricted, Right, Red, Radial
R&D – Research and Development
RA – Rain, Radio Altitude, Resolution Advisory
RAA – Regional Airline Association
RAC – Rules of the air and air traffic services
RAD – Radar
RADAR – Radio Detection And Ranging
RAG -Ragged
RAILS – Runway Aligned Indicator Lighting System
RAIM – Receiver Autonomous Integrity Monitoring
RALT – Regardless of Altitude
RAPID – Rapidly
RAS – Rectified Airspeed or Radar Advisory Service
RB – Relative Bearing
RBI – Relative Bearing Indicator, Runway Bearing Indicator
RCA – Recommended Crossing Altitude, Radio Corporation of America
RCC – Rescue Coordination Centre
RCL – Runway Centreline
RCLS – Runway Centreline Light System
RCU – Radio Control Unit
RDH – Reference Datum Height(for ILS)
RDL – Radial
RDO – Radio
RDPS – Radar Data Processing System
RE – Recent
REA – Ready Message
REC – Receiver
REIL – Runway End Identification Lights
REM – Rapid Eye Movement
REP – Reporting Point or Report
REQ – Request or Requested
RF – Royal Flight, Radio Frequency, Registered Facility
RFU – Radio Frequency Unit
RG – Retractable Gear
RH – Relative Humidity, Right Hand
Rho – Air Density
RIS – Radar Information Service
RL – Rhumb Line
RMI – Radio Magnetic Indicator
RMK – Remarks
RMU – Radio Management Unit
RNAV – Area(Regional) Navigation
RNC – Radio Navigation Charts
RNP – Radio Navigation Plan, Required Navigation Performance
RNSS – Radio Navigation Satellite Services
ROC – Regional Operations Centre
RoC – Rate of Climb
ROD – Record of Decision
RoD – Rate of Descent
RODA – Regardless of Destination Airport
ROFA – Runway Object-Free Area
ROFOR – Route Forecast
RON – Remain Overnight, Research Octane Number(Auto Fuel Rating)
RPL – Repetitive Flight Plan
RPM – Revolutions Per Minute
RPZ – Runway Protection Zone
RQ – Indication of a request
RRTE – Re-Route
RSA – Runway Safety Area
RSC – Rescue sub-centre
RSL – Runway Status Light
RSTN -Restriction(s)
RSU – Runway Supervispry Unit
R/T – Radio Transceiver, Radiotelephony
RTD – Delayed(MET) RTF – Radiotelephony
RTO – Rejected Take-Off
RT/R – Remote Transmitter/Receiver
RVR – Runway Visual Range
RVSM – Reduced Vertical Seperation Minima(1000ft above FL290)
RVV – Runway Visibility Value
R/W – Runway
Rwy – Runway
Rx – Receive
RxTx – Receiver/Transmitter


S – Sierra(phonetic alphabet), South, Wing Surface Area, Secondary Frequency
SA – Sandstorm, Duststorm, Rising Dust or Rising Sand
SAC – Strategic Air Command
SAAC – Society of Amateur Aircraft Constructors
SAE – Society of Automotive Engineers
SAFEPILOT – Sensibly loaded, airspeed maintained, fuel checked, enough runway, properly planned, in practice, learns from others, obtained weather, thorough lookout
SAFI – Semi-Automatic Flight Inspection
SAL – Supplementary Approach Lighting
SALR – Saturated Adiabatic Lapse Rate
SALS – Simple Approach Lighting System
SAP – Soon as Possible
SAR – Search And Rescue
SARBE – SAR Beacon
SARP – Standard and Recommended Practices
SAS – Stability Augmentation System
SAT – Satellite
SATNAV – Satellite Naviagtion(generic)
SATCO – Senior Air Traffic Control Officer
SB – Service Bulletin
SBAC – Society of British Aerospace Companies
SBY – Standby
Sc(or SC) – Stratocumulus
SCATANA – Security Control of Air Traffic and Navigational
SCT – Scattered
Sctr – Sector
SDAU – Safety Data Analysis Unit(of the CAA)
SDU – Satellite Data Unit
SE – Single-Engine, Systems Enigineer, Southeast

SECRA – Secondary Radar
SEL – Sound Exposure Level, Single-Engine Land
SELCAL – Selective Calling System on HF Radio
SEP – Single Engine Piston
SET – Single-Engine Turboprop
SEV – Severe
SFC – Surface, Specific Fuel Consumption
SFE – Synthetic Flight Examiner
SFI – Synthetic Flight Instructor
SG – Specific Gravity, Snow Grains
SGL – Signal
SH – Showers
SHP – Shaft Horsepower
SI – Surveillance Identity(Mode S XPDR), Statutory Instrument

SIC – Second-In-Command
SID – Standard Instrument Departure
SIGMET – Significant Meteorological Service(hazardous weather warning)
SIGWX – Significant Weather
SIM – Simulator
SIMUL – Simultaneous/Simultaneously
SIRO – Simultaneous Intersecting Runway Operation
SKC – Sky Clear
SL – Sea Level
SLMG – Self-Launching Motor Gider
SLP – Speed Limit Point
SM – Statute Miles
SMEL – Single/Multi Engine Land
SMOH – Since Major Overhaul
SMPI – Since Major Periodic Inspection
SMR – Surface Movement Radar
SN – Snow, Serial Number
SNOCLO – Closure of airport due to snow
SNOWTAM – Snow Notam SO – Southern Reporter
SO2 – Sulphur Dioxide
SOL – Safety of Life
SOP – Standard Operating Procedure
SP – Single Pilot
SPA – Single-Pilot Aeroplane
SPCC – Spill Prevention Control and Countermeasure SPECI – Special Weather Report(in code)
SPECIAL – Special Weather Report(in plain language)
SPH – Single-Pilot Helicopter
SPIC – Student Pilot-in-Command
SPIFR – Single-Pilot IFR
SPOH – Since Propeller Overhaul
SPOT – Spot Wind
SQ – Squall
SR – Service Road, Sunrise
SRA – Surveillance Radar Approach, Special Rules Area
SRE – Surveillance Radar Element(PAR)
SRZ – Special Rules Zone
SS – Sandstorm, Sunset
SSA – Sector Safe Altitude(Aerad Approach Charts)
SSB – Single Sideband
SSCVR – Solid State Cockpit Voice Recorder
SSE – South-Southeast
SSR – Standard Stall Recovery, Secondary Surveillance Radar
SST – Supersonic Transport
SSW – South-Southwest
St(or ST) – Stratus
STA – Scheduled Time of Arrival
STAR – Standard Terminal Arrival Route
STC – Supplemental Type Certificate, Sensitivity Time Compensation
STD – Synthetic Training Device, Scheduled Time of Departure
STF – Stratiform
STNR – Stationary
STOL – Short Take-Off and Landing
SVCBL – Serviceable
SVFR – Special Visual Flight Rules
SUA – Special Use Airspace
SW – Shortwave, Southwest
SWAP – Severe Weather Avoidance Plan
SWC – Significant Weather Chart


T – Tango(phonetic alphabet), Temperature, Thrust
TA – Time-Above (noise metric), Transition Altitude
TACT – Tactical Flow Management Working Position
TACAN – Tactical Air Navigation Aid(MIL)
TAF – Terminal Area Forecast(weather forecast)
TAI – International Atomic Time
TAR – Terminal Area Surveillance Radar
TAS – True Airspeed
TB – Transit Bearing
TBO – Time Between Overhaul TC – Turn Coordinator, True Course
TCA – Terminal Control Area
TCAS – Traffic Collision & Avoidance System
TCH – Threshold Crossing Height
TCU – Towering Cumulus
TDC – Top Dead Centre
TDD – Telecommunications Devices for the Deaf
TDME – Terminal DME
TDO – Tornado
TDWR – Terminal Doppler Weather Radar
TDZ – Touchdown Zone
TDZE – Touchdown Zone Elevation(Jeppesen Approach Charts)
TDZL – Touchdown Zone Lights
TE – Track Error
TEMPO – Temporary Change
TEND – Tend /Tending to
TERPs – Thermal Insrument Procedures
TGL – Touch-and-go landing
TGO – Touch-and-Go Operation
TGS – Taxiing Guidance System
TGT – Turbine Gas Temperature
TH – True Heading
THLD – Threshold
THR – Threshold
TKE – Track Error(also TE)
TKOF – Take-Off TL – Until(Weather) TLS – Transponder Landing System
TM – Traffic Management
TMA – Terminal Manoeuvring Area
TMC – Traffic Management Coordinator
TMF – Traffic Management Function
TMG – Track Made Good or Touring Motor Glider
TMPFISCH – Trim/Throttle Friction Nut, Mixture, Primer, Fuel/Flaps, Instruments, Switches, Controls/Carb/Cowl Flaps, Hatches/Harness/Hydraulics(pre-flight take-off checks)
TMS – Traffic Management System
TMU – Traffic Management Unit
TN – True North
TNA – Thermal Neutron Analysis(or Activator)
TNC – Tactical Navigation Chart
TNW – Temporary Navigational Warning Information Bulletin
T/O – Take-Off TOC – Top of climb
TOD – Take-off distance
TODA – Take-Off Distance Available
TOP- Cloud top
TOR – Take-off run
TORA – Take-Off Run Available
TOSS – Take-Off Safety Speed
TOW – Take-Off Weight
TP – Turning Point
TPC – Tactical Plotting Cahrt
TPHP – Typical Peak Hour Passengers
TR – Track, Type Rating, Total Reaction
T/R – Thrust Reversers
TRACAB – Terminal Radar Approach Control in Tower Cab
TRACON – Terminal Radar Approach Control
TRE – Type Rating Examiner
TREND – Weather changes expected in 2 hours (Landing Forecast)
TR – Type-Rating
TRANSCEIVER – Transmitter-Receiver
TRANSPONDER – Transmitter-Responder
TRE – Type-Rating Examiner
TRI – Type Rating Instructor
TRSA – Terminal Radar Service Area
TRTO – Type Rating Training Organisation
TS – Thunderstorm
TSC – Time Since CORE
TSMO – Time Since Major Overhaul
TSN – Time Since New
TSO – Technical Standard Order
TST – Test
TT – Total Time, True Track
TTG – Time-to-go
TTS – Time-to-Station
TTSN – Total Time Since New(same as TSN)
TTW – Time-to-Waypoint
TUC – Time of Useful Consciousness
TURB – Turbulence
TVOR – Terminal VOR
TWEB – Transcribed Weather Broadcast
TWR – Tower
TWY – Taxiway
TWYL – Taxiway link
Tx – Transmit
TX – Transponder
TYP – Type of aircraft
TYRO – Lacking Experience (military)


U – Uniform(phonetic alphabet), Increasing
UA – Air Report(PIREP) UAC – Upper Area Control Centre
UAR – Upper air route
UAV – Unmanned Aerial Vehicle UFN – Until Further Notice
UFO – Unidentified Flying Object
UHF – Ultra-High Frequency(military only)
UIR – Upper flight information region
UL – Ultralight
UNL – Unlimited
UNOS – Undershoot on North, Overshoot on South (Northern Hemisphere only)
UP – Unknown Precipitation
U/S – Unserviceable
USG – US Gallons
UTC – Coordinated Universal Time
UWB – Ultra-Wide Band
UV – Ultraviolet


V – Varying, Victor(phonetic alphabet), Velocity(TAS)
V1 – Critical Engine Failure Velocity(Takeoff Decision Speed)
V2 – Take-Off Climb Velocity
VAor VMAN – Manoeuvring Speed(maximum structural speed allowed for full control deflection)
VA – Volcanic Ash
VAC – Volts AC
VAD – Visual Approach/Departure
VAL – In Valleys, Visual Approach and Landing(Chart)
VAR – Variation
VASI(S) – Visual Approach Slope Indicator System
VAT – Nominal Speed at Threshold
VB – Turbulence Penetration Speed
VC – Vicinity of Aerodrome
VCY – Vicinity
VDMaximum Dive Speed(for certifiaction only)
VDC – Volts DC
VDF – Very High Frequency Direction Finding
VER – Vertical
VFE – Maximum Speed Flaps Extended(down)
VFR – Visual Flight Rules
VHF – Very High Frequency
VHF-COM – Radio Transceiver (R/T)
VHF-COM/NAV – Combined Radio & Navigation Receiver
VHF-NAV – Navigation Radio
VIP – Very Important Person
VIS – Visual, Visibility
VLA – Very Light Aircraft
VLE – Maximum Speed Landing Gear Extended
VLF – Very Low Frequency
VLO – Maximum Speed Landing Gear Operation(extending or retracting)
VMC – Visual Meteorological Conditions
VMH – Visual Manoeuvring Height
V-n – Velocity/Load
VNAV – Vertical Navigation(GLS)
VNE – Speed Never Exceed
VNO – Speed Normal Maximum, (maximum structural cruising speed
VOLMET – In-flight Meteorological Service(Latin Volens-Flying)
VOR – Very High Frequency Omni-Directional Radio Range
VOR/DME – Combined VOR/DME Station
VOT – VOR airborne equipment test facility
VORTAC – VOR and TACAN combination(MIL)
VRRotation Speed
VRA – Rough Air Airspeed
VRB – Variable
VRP – Visual Reference Point
VSB – VHF Survival Beacon
VSI – Vertical Speed Indicator
VS0 – Stall speed gear & flaps down
VS1 – Stall speed ‘clean’ i.e. flaps up, gear up(if retractable)
VSSE – Minimum Safe Single Engine Speed
V/STOL – Vertical or Short Take-Off and Landing
VTOL – Vertical Take-Off and Landing
VTURB – Turbulence Penetration Speed(a.k.a. VB) VV/// – Cloud base not discernible, state of sky obscured
VX – Speed setting maximum angle in a climb
VXSE – Speed setting maximum angle in a climb, 1 engine inoperative
VY – Best vertical speed in a climb
VYSE – Best vertical speed in a climb, 1 engine inoperative


W – Whiskey(phonetic alphabet), West, Weight, White
WAC – World Aeronautical Chart
WAAS – Wide-Area Augmentation System(GNSS)
WAT – Weight, Altitude, Temperature
WC – Weather Coordinator
WCA – Wind Correction Angle
WDSPR – Widespread
WEF – With effect from or effective from
WGS – World Geodesic System
WIE – With immediate effect or effective immediately
WILCO – Will Comply
WIP – Work In Progress
WKN – Weakening
WMO – World Meteor WNW – West-Northwest
WOSSSSS – Wind, Obstacles, Size/Shape of field, Surface/Slope, Shoots, Sun, S(c)ivilisation
WP – Waypoint
WPT – Waypoint
WRDA – Weapons Range Danger Area
WRNG – Warning
WS – Windshear
WSFO – Weather Service Forecast Officer
WSO – Weather Service Office
WSW – West-Southwest
W/V – Wind Velocity
Wx – Weather


X – X-Ray(phonetic alphabet), Heavy(MET e.g. XXRA – heavy rain)
XC – Cross-country
XPDR – Transponder
XPOND – Transponder
XTK – Cross Track, Cross Track Error


Y – Yankee(phonetic alphabet)
YD – Yaw Damper


Z – Zulu(phonetic alphabet), a.k.a. UTC
ZAC – Zenith Aircraft Company
ZFW – Zero Fuel Weight

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