A Amber
A/A Air to air
A/G Air-to-ground
AAA Amended meterological message
AAAA Aerial Application Association of Australia
AAC Airworthiness Advisory Circular
AACC Area approach control centre
AAD Assigned altitude deviation
AAIM Aircraft Autonomous Integrity Monitor
AAIS Automatic aerodrome information service
AAL Above aerodrome level
AAR Authorised Airworthiness Representative
AAT Administrative Appeals Tribunal
ABAA Amateur Built Aircraft Acceptance
ABAS Aircraft Based Augmentation System
ABF Australian Ballooning Federation
ABI Advance boundary information
ABM Abeam
ABN Aerodrome beacon
ABT About
ABV Above...
AC Advisory Circular
AC Altocumulus (met)
ACA Australian Commonwealth Authority
ACARS Aircraft communication addressing and reporting system (pronounced 'AY-CARS')
ACAS Airborne Collision Avoidance System
ACC Area control centre
ACCID Initial notification of an aircraft accident
ACD Airways clearance delivery
ACFT Aircraft
ACJ-XXX Advisory Circular Joint (issued by the JAA, can be followed by a country code)
ACK Acknowledge
ACL Altimeter check location
ACN Aircraft classification number
ACN Australian company number
ACPT Accept, accepted
ACROB Acrobatics
Act the Civil Aviation Act 1988
ACT Active, activated, activity
AD Aerodrome
AD Airworthiness Directive
ADA Advisory area
ADAO Authorised Design Approval Organisation
ADC Aerodrome chart
ADDGM Aerodrome diagrams
ADDN Addition, additional
ADF Automatic Direction Finding (equipment)
ADF Australian Defence Force
ADIZ Air Defence Identification Zone
ADJ Adjacent
ADO Aerodrome office
ADQ Adequate aerodrome
ADR Advisory route
ADS The address (when this abbreviation is used to request a repetition, the question (IMI) precedes the abbreviation, eg IMI ADS) (to be used in AFS as a procedure signal)
ADS Automatic Dependent Surveillance
ADS-B Automatic Dependent Surveillance - Broadcast
ADS-C Automatic Dependent Surveillance - Contract
ADSU Automatic Dependent Surveillance Unit
ADZ Advise
AEB CASA's Airworthiness Engineering Branch
AEP Aerodrome emergency plan
AER Authorised Engineering Representative
AERIS Automatic en route information service
AFAP Australian Federation of Air Pilots
AFCS Automatic flight control system
AFIL Flight notification: - filed in the air, or - indicating the position at which ATS services will first be required
AFIS Aerodrome flight information service
AFM Aircraft Flight Manual
AFM Yes, affirm, affirmative, that is correct
AFRU Aerodrome Frequency Response Unit (also known as a "beepback" unit)
AFS Aeronautical fixed service
AFT After
AFTN Aeronautical fixed telecommunication network
AFZ Australian fishing zone(s)
Ag Agriculture
AGA Again
AGD Attorney-General's Department
AGL Above Ground Level
AH Artificial Horizon
AH After hours
AIC Aeronautical Information Circular
AIDC Air traffic services inter-facitility data communications
AIP Aeronautical Information Publication
AIP ENR Aeronautical Information Publication En-route
AIP ERSA Aeronautical Information Publication En-route Supplement Australia
AIP GEN Aeronautical Information Publication General
AIRAC Aeronautical Information Regulation and Control
AIRC Aeronautical Information and Control
AIREP Air-Report
AIRMET Information in plain language concerning weather significant to light aircraft operations at or below 10,000FT
AIS Aeronautical Information Service
AL Approach Lights
ALA Aircraft Landing Area
ALA Aeroplane landing area
ALA Alighting area
ALA/HLS Aircraft Landing Area/Helicopter Landing Site
ALAEA Australian Licensed Aircraft Engineers Association
ALARP As Low as Reasonably Practical
ALERFA Alert phase
ALI Airworthiness Limitation Item
ALM Aircraft Landing Minima
ALR Alerting Message
ALRS Approach lighting system
ALS Approach Lighting System
ALT Altitude
ALTN Alternate, Alternating (light alternates in colour)
ALTN Alternate (aerodrome)
AMA Area minimum altitude
AMC Acceptable Means of Compliance
AMD Amend, Amended
AMDT Amendment (AIP amendment)
AME Aircraft Maintenance Engineer
AMM Aircraft Maintenance Manual
AMO Approved Maintenance Organisation
AMP Aircraft Maintenance Program
AMPA Authorised Maintenance Personnel Assessor
AMRD Australian Maintenance Requirements Document
AMS Aircraft Maintenance Specialist
AMSA Australian Maritime Safety Authority
AMSL Above Mean Sea Level
AMSS Aeronautical mobile satellite service
AMT Aircraft Maintenance Technician
ANA Air Navigation Act
ANC Aeronautical Chart 1:50,000 (followed by name/title)
ANCS Aeronautical navigation chart - small scale (followed by name/title and scale)
ANO Air Navigation Order
ANS Answer
ANTA Australian National Training Authority
ANVIS Aviator Night Vision Imaging Systems
AO Air Operator
AOA Angle of Attack = Thx Bmb92
AOC Air Operators Certificate
AOC Aerodrome Obstacle Chart (followed by name/title)
AOCM Air Operators Certification Manual
AOD Alcohol and Other Drug
AOG Aircraft On Ground
AOPA Aircraft Owners and Pilots Association
AP Airport
APAPI Abbreviated Precision Approach Path Indicator (pronounced 'AY-PAPI')
APCH Approach
APDC Aircraft Parking/Docking Chart (followed by name/title)
APF Australian Parachute Federation
APMA Australian Parts Manufacturer Approval
APN Apron
APP Approach Control
APRX Approximate, Approximately
APSG After Passing
APU Auxillary power unit
APV Approach with Vertical Guidance
APV Approve, Approved, Approval
AQZ Area QNH Zone
ARC Area Chart
ARFFS Aerodrome Rescue and Fire Fighting Service (sometimes referred to as RFFS)
ARFL Aeroplane Reference Field Length
ARFO Area Forecast
ARH Aircraft Registration Holder
ARM Airspace Risk Model
ARM Aircraft Recovery Manual
ARN Aviation Reference Number
ARNG Arrange
ARO Air traffic services reporting office
AROC Aircraft radio operator certificate
ARP Aerodrome reference point
ARP Air-Report (message type designator)
ARQ Automatic error correction
ARR Arrive, Arrival
ARS Special Air-Report (message type designator)
ARST Arresting (specify (part of) aircraft arresting equipment)
AS Altostratus (meteorological)
AS Australian Standard
ASA Australian Skydiving Association
ASAC Australian Sports Aviation Confederation
ASAP As Soon as Possible
ASC Ascend to or ascending
ASDA Accelerate-stop distance available
ASE Airborne Support Equipment
ASE Altimetry System Error
ASEPTA Approved Single-engine Turbine Aeroplane
ASF Aviation Safety Forum
ASH Aviation Services Handbook
ASI Air Speed Indicator
ASI Aviation Safety Index
ASIR Aviation Safety Incident Report
ASPH Asphalt
ASR Area Surveillance Radar
ASRA Australian Sport Rotorcraft Association
ASSI Air Safety Support International- a wholly-owned subsidiary of the UK Civil Aviation Authority
ASTM American Society for Testing Materials
ASTRA Australian Strategic Air Traffic Management Group
AT-VASIS Abbreviated 'T' Visual Approach Slope Indicator System (pronounced 'AY-TEE-VASIS')
AT... At (followed by time at which weather change is forecast to occur)
ATA Actual Time of Arrival
ATA Air Transport Association
ATC Air Traffic Control (in general)
ATD Actual Time of Departure
ATE Automatic Test Equipment
ATEL/ANAV Aeronautical Telecommunication and Radio Navigation Services
ATFM Air Traffic Flow Management
ATIS Automatic terminal information service
ATM Air traffic management
ATN Aeronautical telecommunications network
ATO Aviation Testing Officer
ATP At.. (time or place)
ATPL Airline Transport Pilot Licence
ATS Air Traffic Service(s)
ATSB Australian Transport Safety Bureau
ATSO Australian Technical Standard Order
ATSOA Australian Technical Standard Order Authorisation
ATTN Attention
ATZ Aerodrome traffic zone
AUF Australian Ultralight Federation (now Recreational Aviation Australia)
AUTH Authorised, Authorisation
AUW All Up Weight
AUX Auxiliary
AVBL Available
AVG Average
AVGAS Aviation Gasoline
AVM Abrupt Vertical Manoeuvres (by the MIL)
AWB Airworthiness Bulletin
AWIB Aerodrome Weather Information Broadcast
AWK Aerial Work (Air work - general aviation)
AWO Aerial work operation
AWS Automatic Weather Station
AWTA Advise as to wh

B Blue
BA Braking action
BAK Basic aeronautical knowledge
BASA Bilateral Aviation Safety Agreement
BASE Cloud Base (met)
BCFG Fog Patches (met)
BCN Beacon (aeronautical ground light)
BCST Broadcast
BDRY Boundary
BECMG Becoming
BETA Manually controlled mode for constant speed propellers or turbo prop aircraft
BFR Before
BIP-M Basic Instruction Package for Meteorologists
BIPMT Basic Instruction Package for Meteorological Technicians
BITE Built In Test Equipment
BKN Broken (cloud descriptor) (met)
BL... Blowing (followed by DU=dust, SA=sand or SN=snow)
BLDG Building
BLO Below Clouds
BLW Below
BOM Bureau of Meteorology
BOMB Bombing
BR Mist
BRF Short (used to indicate type of approach)
BRG Bearing
BRKG Braking
BRW Brakes release weight
BS Broadcasting Station (Commercial)
BTL Between Layers
BTN Between
BVLOS Beyond visual line of sight

C Degrees Celsius (Centigrade)
C Centre (Runway)
CA Course Acquisition
CA/GRO Certified Air/Ground Radio Operator
CA/GRS Certified Air/Ground Radio Service
CAA NZ Civil Aviation Authority New Zealand
CAAP Civil Aviation Advisory Publication
CAGRO Certified Air Ground Radio Operation
CAMO Continuing Airworthiness Management Organisation
CAMP Continuous Airworthiness Maintenance Program
CAO Civil Aviation Order
CAR Civil Aviation Regulations 1988
CAS Calibrated air speed
CASA Civil Aviation Safety Authority
CASR Civil Aviation Safety Regulations 1998
CASR Civil Aviation Safety Regulation
CAT Category
CAT Clear Air Turbulence
CAVOK Visibility, cloud and present weather better than prescribed values or conditions
CB Cumulonimbus (met)
CBT Competency-based Training
CC Cirrocumulus (met)
CCA Corrected meteorological message (for CCB, CCC..etc., in sequence) (message type designator)
CCF Capability Check Flight
CCTS Circuits
CD Candela
CDCCL Critical Design Configuration Control Limit
CDI Course Direction Indicator
CDL Configuration Deviation List
CDN Coordination (message type designator)
CEN En Route and Area ATC unit
CEO Chief Executive Officer
CET Clearance Expiry Time
CF Change Frequency to
CFI Chief Flying Instructor
CFIT Controlled Flight into Terrain
CFL Cleared Flight Level
CFM Confirm, I confirm
CG Centre of gravity
CGL Circling guidance light(s)
CH This is a channel continuity check of transmission to permit comparision of your record of channel-sequence numbers of messages received on the channel (to be used in AFS as a procedure signal)
CHG Modification (message type designator)
CHTR Charter
CI Cirrus (met)
CIDIN Common ICAO data interchange network
CIR Command Instrument Rating
CIT Near, Over Large Town(s)
CIV Civil
CK Check
CL Centre Line
CLA Clear type of ice formation
CLBR Calibration
CLD Cloud (met)
CLG Calling
CLIAS Climbing Indicated Airspeed
CLMAX Maximum Co-efficient of Lift
CLR Clear, Cleared to... Clearance
CLSD Closed, Close, Closing
CM (cm) Centimetre
CMB Climb to or Climbing to
CMM Component Maintenance Manual
CMPL Configuration, Maintenance and Procedures
CMPL Completion, Completed, or Complete
CMR Certification Maintenance Requirements
CMSD Commissioned
CNL Cancel
CNL Flight plan cancellation message
CNS Communications, Navigation and Surveillance
COA Certificates of Approval (issued to maintenance organisations)
CofA Certificate of Airworthiness
COM Communications
CONC Concrete
COND Condition
CONS Continuous
CONST Construction, Constructed
CONT Continue(s), Continued
COOR Coordinate, Coordinated
COORD Coordinates
COP Change over point
CoR Certificate of Registration
COR Correct, Corrected, Correction
COS Conical Surface
COT At the Coast, Coastal
COV Cover, Covered, Covering
CP Chief Pilot
CPDLC Controller-Pilot Data Link Communication
CPL Commercial Pilot Licence
CPL Current flight plan
CRC Cyclic redundancy check
CRIS Cost Recovery Impact Statement
CRM Crew Resource Management
CRZ Cruise
CS Cirrostratus (met)
CS Call sign
CSDD Common Support Data Dictionary published by the Air Transport Association of America (ATA). The CSDD replaces the WATOG.
CSU Constant Speed Unit
CTA Control Area
CTAF Common Traffic Advisory Frequency
CTAF(R) Common Traffic Advisory Frequency - (Radio)
CTAM Climb to and maintain
CTC Category Technical Competency
CTC Contact
CTL Control
CTN Caution
CTR Control Zone
CU Cumulus (met)
CUF Cumuliform (met)
CUST Customs
CVR Cockpit voice recorder
CW Carrier Wave
CWY Clearway

D Deleted
D Downward (tendency in RVR (Runway visual range) during previous 10 minutes)
D-ATIS Data Link Automatic Terminal Information Service (pronounced'DEE-ATIS')
D-VOLMET Data Link VOLMET
D... Danger Area (followed by identification)
DA Decision Altitude
DA/H Decision Altitude/Height
DALR Dry Adiabatic Lapse Rate
DAME Designated Aviation Medical Examiner
DAO Designated Aviation Ophthamologist
DAP Departure and Approach Procedures
DCD Double channel duplex
DCKG Docking
DCMSD Decommissioned
DCPC Direct Controller-Pilot Communications
DCS Double channel simplex
DCT Direct (in relation to flight plan clearances and type of approach)
DE Form (used to preceed the call sign of the calling station) (to be used in AFS as a procedure signal)
DEC December
DEG Degrees
DEP Depart, Departure, Departed, Departing, Departure Message
DER Departure End of Runway
DER Designated Engineering Representative
DES Descend to, Descending to
DEST Destination
DETRESFA Distress Phase
DEV Deviation, Deviating
DF Direction Finder/ Finding
DFDR Digital Flight Data Recorder
DFTI Distance from touchdown indicator
DGA Distance Measuring Equipment or Global Positioning Satellite System Arrival
DH Decision Height
DIF Diffuse
DISP Displaced
DIST Distance
DIV Diversion, Divert, Diverting
DLA Delay (message type designator)
DLIC Data Link Initiation Capability
DLY Daily
DMC Direct Maintenance Cost
DME Distance Measuring Equipment
DMEN DME (International)
DMEP DME (International Precision used in conjunction with Microwave Landing System)
DNG Danger, Dangerous
DOC Direct Operating Cost
DOC Documents
DoD Department of Defence
DOM Domestic
DP Dew Point Temperature
DP Discussion Paper
DPT Depth
DR Dead Reckoning (navigation)
DR... Low drifting (followed by DU=dust, SA=sand or SN=snow)
DRG During
DS Dust storm
DSB Double sideband
DTAM Descend to And Maintain
DTG Date-Time Group
DTHR Displaced Runway Threshold
DTRT Deteriorate, Deteriorating
DTW Dual tandem wheels
DU Dust
DUC Dense Upper Cloud (met)
DUPE This is a duplicate message (to be used in Aeronautical Fixed Service as a procedure signal)
DUR Duration
DVOR Doppler VOR
DW Dual wheels
DZ Drizzle

E East, East Longitude
E E E Error (to be used in AFS as a procedure signal)
EASA European Aviation Safety Agency
EAT Expected Approach Time
EB Eastbound
ECAR European Civil Aviation Requirement (formerly JAR)
EDTO Extended Diversion Time Operations
EET Estimated Elapsed Time
EFB Electronic Flight Bag
EFC Expect further clearance
EGNOS European Geostationary Navigation Overlay System
EGPWS Enhanced Ground Proximity Warning System
EHF Extremely high frequency (30,000 to 300,000 MHz)
EHR Encumbrance Holder Register
ELBA Emergency locator beacon-aircraft
ELEV Elevation
ELR Extra Long Range
ELT(S) Emergency Locator Transmitter (Survival)
EM Engine Manual
EM Explanatory Memorandum (submitted to EXCO with regulation amendment)
EM Emission
EMBD Embedded in a Layer (to indicate cumulonimbus embedded in layers of other clouds)
EMERG Emergency
EMS Emergency Medical Service
EMS Environment Management System
END Stop-end (related to RVR)
ENDCE Endurance
ENE East North-East
ENG Engine
ENR En Route
ENRC En Route Chart (followed by name/title)
EOBT Estimated off Blocks Time
EPA Environment Protection Agency
EPIRB Electronic Position Indicating Radio Beacon (marine term.)
EQPT Equipment
ER Here..or herewith
ERC En-route Chart
ERP Emergency Response Plan
ERSA En-route Supplement Australia
ES Explanatory Statement (tabled with regulations in Parliament)
ESD Electrostatic sensitive discharge
ESDE ESD equipment
ESE East Southeast
ESIR Electronic safety incident report
EST Estimate or estimated or estimate (message type designator)
ETA Estimated Time of Arrival, Estimating Arrival
ETCM Engine trend and condition monitoring
ETD Estimated Time of Departure, Estimating Departure
ETO Estimated Time Over significant point
ETOPS Extended range operations by turbine-engined aeroplanes
ETP Equi Time Interval
ETT Estimated Time Interval
EV Every
EVLOS Extended visual line of sight
EVU Enforceable Voluntary Undertaking
EXC Except
EXCO Executive Council
EXER Exercises, Exercising, to exercise
EXP Expect, Expected, Expecting
EXTD Extend, Extending, Extended

F Fixed (chart symbol)
FAA Federal Aviation Administration of the USA
FAAOC Foreign Aircraft Air Operator's Certificate
FAC Facility, Facilities
FADEC Full Authority Digital Engine Control
FAF Final Approach Fix
FAL Facilitation of International Air
FAP Final Approach Point
FARs Federal Aviation Regulations (Federal Aviation Administration of the USA)
FATO Final approach and take-off area
FAWP Final Approach Waypoint
FAX Facsimile Transmission
FBL Light (used to indicate the intensity of WX phenomena, interference or static reports, eg BL RA = light rain)
FC Funnel Cloud (tornado or water spout)
FCST Forecast
FCT Friction coefficient
FD Fault Detection
FDE Fault detection and exclusion (in relation to GPS equipment)
FDL Fixed Distance Lighting
FDPS Flight Data Processing system
FDS Flight Director System
FEW Few (cloud descriptor)
FFR Flood, Fire Relief
FG Fog
FIA Flight Information Area
FIC Flight Information Centre
FIO Flight Information Office
FIR Flight Information Region
FISA Flight information service (automated)
FISS Flight Information Service Station
FIX Fault Isolation Manual
FL Flight Level
FLD Field
FLG Flashing
FLIR Forward Looking Infra Red
FLR Flares
FLT Flight
FLTCK Flight check
FLUC Fluctuating, Fluctuation, Fluctuated
FLW Follow(s), Following
FLY Fly, Flying
FM From
FM... From (followed by time weather change is forecast to begin)
FMS Flight Management System
FMU Flow Management Unit
FNA Final Approach
FNPT Flight and Navigation Procedures Trainer
FOD Foreign Object Damage
FOI Flying Operations Inspector
FPD Flight Plan Designator
FPL Filed Flight Plan Message
FPM Feet per Minute
FPR Flight Plan Route
FPV First person view
FR Fuel Remaining
FREQ Frequency
FRM Fault Reporting Manual
FRMS Fatigue Risk Management System
FRNG Firing
FRONT Front (relating to weather)
FRQ Frequent
FS Flight Service (in general)
FSA Flight Safety Australia
FSL Full Stop Landing
FSP Fish Spotting
FSS Flight service station
FST First
FT Feet
FTD Flight training device
FTE Full time equivalent
FTO Flight Training Organisation
FU Smoke
FXD Fixed
FZ Freezing
FZDZ Freezing Drizzle
FZFG Freezing Fog
FZL Freezing Level
FZRA Freezing Rain

G Gravity
G Green
G/A Ground-to-air
G/A/G Ground-to-air and air-to-ground
GA Go Around
GA Go ahead, resume sending (to be used in AFS as a procedure signal)
GA General Aviation
GAAP General Aviation Aerodrome Procedures
GAMET Area forecast for low-level flights
GAPAN Honourable Company of Air Pilots, Australia, Inc.
GBAS Ground Based Augmentation System
GCA Ground Controlled Approach
GCN General Computing Network (operated by Airservices Australia)
GDOP Geometric Dilution of Precision
GEN General
GEO Geographic, true
GES Ground Earth Station
GFA The Gliding Federation of Australia
GFY Glider Flying
GHA Ground handling agents
GIVD Gravity Induced Vestibular Dysfunction
GLD Glider
GLOC Gravity Induced Loss of Consciousness
GLONASS Global Orbiting Navigation Satellite System (pronounced 'GLO-NAS')
GM Guidance Material
GMC Ground Movement Chart (followed by name/title)
GND Ground
GNDCK Ground Check
GNS Global Navigation System
GNSS Global navigation satellite system
GP Guiding principles
GP Glide Path
GP FLG Group Flashing (number) (used in conjunction with aerodrome lighting)
GPI Glide Path Intercept
GPS Global positioning system (see GNSS)
GPWS Ground proximity warning system
GR Hail
GRAD Minimum Required Climb Gradient
GRAS Ground Based Regional Augmentation System
GRASS Grass Landing Area
GRIB Processed meteoroglogical data in the form of grid point values expressed in binary form (aeronautical meterological code)
GRVL Gravel
GS Groundspeed
GS Small Hail and/or Snow Pellets
GSE Ground Support Equipment
GUND Geoid Undulation

H24 Continuous day and night service
HAA Height Above Aerodrome
HAA Helicopter Association of Australia
HAAMC Head of Aircraft Airworthiness and Maintenance Control
HAM Head of Aircraft Maintenance
HAMC Head of Aircraft Maintenance Control
HAPI Helicopter approach path indicator
HAT Height Above Threshold
HBN Hazard Beacon
HDF High frequency direction-finding station
HDG Heading
HDS Hours of Daylight Saving
HEL Helicopter
HF Human Factors
HF High Frequency (3000 to 30,000 KHZ)
HFEM Human Factor and Error Management System
HGFA Hang Gliding Federation of Australia Inc
HGS Heads-up Guidance System
HGT Height, Height Above
HIAL High Intensity Approach Lighting
HIOL High Intensity Obstacle Lights
HIRL High Intensity Runway Lighting
HJ Sunrise to Sunset
HLDG Holding
HLS Helicopter Landing Site
HMI Human-machine Interface
HN Sunset to Sunrise
HO Service available to meet operational requirements
HOFO Head of Flying Operations
HOO Head of Operations
HOSP Hospital Aircraft
HOTAS Head of Training and Standards
HOTC Head of Training and Checking
HP Horse Power
HPA HectoPascal
HR Hours
HS Homestead
HS Service available during hours of scheduled operations
HSL Hold Short Lights
HUD Head Up Display
HURCN Hurricane
HVDF High and very high frequency direction finding stations (at the same location)
HVY Heavy
HVY Heavy (used to indicate the intensity of WX phenomena, eg HVY RA = heavy rain)
HX No specific working hours
HYR Higher
HZ Haze
HZ (hz) Hertz
HZS Horizontal Surface

IA Inspection authorisation
IAC Instrument approach chart (followed by name/title)
IAF Initial Approach Fix
IAL Instrument Approach and Landing Chart
IAO In and out of clouds
IAP Instrument Approach Plate
IAR Intersection of air routes
IAS Indicated air speed
IATA International Air Transport Association
IAW In Accordance With
IAWP Initial Approach Way-point
IBN Identification Beacon
IC Ice Crystals (MET code)
ICA Instructions for continuing airworthiness (issued by manufacturer or designer)
ICAO International Civil Aviation Organization
ICE Icing, Ice
ICUS In-command Under Supervision
ID Identifier, identify
IDENT Identification
IF Instrument Flight
IF Intermediate Approach Fix
IFF Identification Friend/Foe
IFR Instrument flight rules
IFSD In-flight Shutdown
IG Implementation Group
IGA International general aviation
ILS Instrument Landing System
IM Inner Marker
IMC Instrument meteorological conditions (other than VMC)
IMC Indirect Maintenance Cost
IMG Immigration
IMI Interrogation sign
IMPR Improve, Improving, Improvement
IMT Immediate, Immediately
INA Initial approach
INBD Inbound
INC In Cloud
INCERFA Uncertainty Phase
INFO Information
INOP Inoperative
INP If not possible
INPR In progress
INS Inertial Navigation System
INSTL Install, Installed, Installation
INSTR Instrument
INT Intersection
INTER Intermittent, Intermittently (meteorological)
INTL International
INTRG Interrogator
INTRP Interrupt, Interruption, Interrupted
INTSF Intensify, Intensifying
INTST Intensity
IoA Instrument of appointment
IOC Indirect Operating Cost
IOE Initial Operational Experience
IPC Illustrated Parts Catalogue
IR Ice on runway
IREX Instrument Training Examination
IRM Immediately Reportable Matters
IRS Internal Reporting System
ISA International Standard Atmosphere
ISB Independent Sideband
ISIM Integrated Safety Investigation Methodology
ISO9000 International Organization for Standardization
ISOL Isolated
ITT Interstage Turbine Temperature
IWI Illuminated Wind Indicator
IWP Intermediate Way-point

J-BAR Jet Barrier
JAA Joint Aviation Authorities (of Europe)
JAR Joint Aviation Requirements (of the European JAA)
JAR-OPS JAR Operations
JTSO Joint Technical Standard Order
JTST Jet Stream

KDR Knowledge Deficiency Report
KG (kg) Kilograms
KHZ (kHz) Kilohertz
KM (km) Kilometers
KMH (km/h) Kilometers per hour
KPA (kPa) Kilopascals
KT (kt) Knots
KW (kw) Kilowatts

L Left (runway identification)
L Locator (see LM, LO)
LAAS Local Area Augmentation System
LAHSO Land and Hold Short Operations
LAME Licensed Aircraft Maintenance Engineer
LAN Inland
LAT Latitude
LDA Landing distance available
LDG Landing
LDI Landing Direction Indicator
LDP Landing decision point
LEN Length
LF Low Frequency (30 to 300 KHZ)
LGT Light, Lighting
LGTD Lighted
LIH Light Intensity High
LIL Light Intensity Low
LIM Light Intensity Medium
LIOL Low Intensity Obstacle Lights
LIRL Low Intensity Runway Lights
LJR Low Jet Route
LL Lower Limit
LLN Low-level Navigation (by the MIL)
LLO Low Level Operations (by the MIL)
LLZ Localizer
LM Locator (middle)
LMT Local mean time
LO Locator (outer)
LOC Locally, Location, Located, Local
LOE Lane of Entry
LONG Longitude
LOSA Line Operations Safety Audit
LPT Liquid Penetrant Test
LRCS Long-range communication system
LRG Long Range
LRI Line Replaceable Item
LRNS Long-range navigation system
LRU Line Replaceable Unit
LSA Light Sport Aircraft
LSALT Lowest safe altitude
LSd CASA's Legal Services Division
LTD Limited
LUL Lowest Usable Level
LV Light and Variable (relating to wind)
LVE Leave, Leaving
LVL Level
LYR Layer, Layered

M Mach number (followed by figures ie .02 = Mach .02)
M (m) Metres (preceded by figures)
M/E Multi-engine
MAAT Manual Authoring and Assessment Tool
MAE Men and Equipment
MAG Magnetic
MAHWP Missed Approach Holding Way-point
MAINT Maintenance
MAN Manual
MAP Aeronautical Maps and Charts
MAP Manifold Air Pressure
MAPT Missed Approach Point
MAR At Sea
MAUW Maximum All Up Weight
MAWP Missed Approach Waypoint
MAX Maximum
MBST Microburst
MBZ Mandatory Broadcast Zone
MCC Multi-crew Co-ordination
MCM Maintenance control manual
MCQFS Manual of criteria for the qualification of flight simulators ICAO Doc 9625-AN/938
MCUR Mean Cycles Between Unscheduled Removals
MCW Modulated Continuous Wave
MDA Minimum Descent Altitude
MDF Medium Frequency Direction Finding Station
MDR Major Defect Report
MEA Minimum En-route Altitude
MED Medical
MEL Minimum equipment list
MERSITAB Manufacturing, Engineering and Related Services Industry Training Advisory Body
MET Meteorological, Meteorology
MET REPORT Aviation routine weather report
METAR Aviation routine weather report (in aeronautical meteorological code)
METRAD MET Radar
MF Medium Frequency (300 to 3000 KHZ)
MHZ (mhz) Megahertz
MIFG Shallow Fog
MIL Military
MIL-STD Military Standard
MIN Minutes
MIOL Medium Intensity Obstacle Lights
MIRL Medium Intensity Runway Lights
MISC Miscellaneous
MKR Marker Radio Beacon
MLJ Military Low Jet
MLJR Military Low Jet Route
MLS Microwave Landing System
MLW Maximum Landing Weight
MM Middle Marker
MMEL Master minimum equipment list
MNM Minimum
MNT Monitor, Monitoring,
MNTN Maintain, Maintained, Maintaining
MOA Military Operating Area
MOC Minimum obstacle clearance (required)
MOD Moderate, Moderately
MOD Moderate (used to indicate the intensity of WX phenomena, interference or static reports, eg MOD RA = moderate rain).
MON Above Mountains
MOPS Minimum Operational Performance Standards
MOS Manual of Standards
MOU Memorandum of understanding
MOV Move, Moved, Moving, Movement
MOWP Method of Working Plan
MPD Maintenance Planning Data
MPI Magnetic Particle Inspection
MPL Multi-crew Pilot Licence
MPS Metres per Second
MPT Magnetic Particle Inspection Technician
MRB Maintenance Review Board
MRBR Maintenance Review Board Report
MRG Medium Range
MRO Maintenance, repair and overhaul
MRP ATS/MET Reporting Point
MS Minus
MSA Minimum sector altitude
MSAS Multi-function Transport Satellite (MTSAT) Satellite-based Augmentation System
MSDS Material Safety Data Sheets
MSG Message
MSG Maintenance Steering Group
MSG-3 Maintenance Steering Group Logic Process
MSI Maintenance Significant Item
MSL Mean Sea Level
MSOS Maintenance specific operation specification
MSSR Monopulse Secondary Surveillance Radar
MT Mountain
MTBF Mean Time Between Failure
MTBR Mean Time Between Removals
MTBUR Mean Time Between Unscheduled Removals
MTO Maintenance training organisation
MTOW Maximum take-off weight
MTP Maximum Tyre Pressure
MTSAT Multi-function Transport Satellite
MTTF Mean Time To Failure
MTTR Mean Time To Repair
MTTUR Mean Time To Unscheduled Removal
MTUR Special Term For Data Transmittal
MTW Mountain waves
MVA Minimum Vector Altitude
MWO Meteorological Watch Office
MX Mixed type of ice formation (white and clear)

N North, North Latitude
N1 Gas Generator Speed
N2 Second Stage Turbine Speed
NAA National Airworthiness Authority (for a country other than Australia)
NAD Non-acqueous Developer
NAIPS National aeronautical information processing system
NANDTB National Aerospace Non-destructive Testing Board
NANU Notice Advisory to NavStar Users
NAP Noise Abatement Procedures
NAS National Airspace System
NASC National AIS System Centre
NAT NAVAID Training
NAV Navigation
NAVAID Navigation Aid
NAWD Non-acqueous Wet Developer
NB Northbound
NBFR Not Before
NC No Change
NDB Non-directional Radio Beacon
NDI Non-destructive inspection
NDT Non-destructive testing
NE Northeast
NEG Negative, No. Permission not granted or, That is not correct
NFRM Notice of Final Rule Making
NG Gas Generator Speed
NGT Night
NIL None
NM Nautical Miles
NML Normal
NNE North North-East
NNW North North-West
NOF International NOTAM Office
NOSIG No Significant Change
NOTAM Notice To Airmen
NOZ Normal Operating Zone
NP Propeller Speed
NPA Non-precision approach (procedures at aerodromes)
NPC Notice of proposed change (consultation for amendment to a MOS)
NPRM Notice of proposed rule making
NSC Nil Significant Cloud
NTA No TAF Amendment
NTL National
NTS Negative Torque Sensing System
NTSB National Transportation Safety Board (of the USA)
NTZ No-transgression zone
NVD Night Vision Device
NVED Night Vision Enhancement Devices
NVET National vocational education and training
NVFR Night Visual Flight Rules
NVG Night Vision Goggles (by the MIL)
NVIS Night Vision Imaging Systems
NW North-West
NXT Next
NZ New Zealand
NZ CAA New Zealand Civil Aviation Authority
NZS New Zealand Standard

O/R On Request
OAR Office of Airspace Regulation
OAT Outside Air Transport
OAT Outside Air Temperature
OBPR Office of Best Practice Regulation
OBPR Office of Best Practice Regulation
OBS Observe, Observed, Observation
OBS Omni Bearing Selector
OBSC Obscure, Obscured, Obscuring
OBST Obstacle
OBSTR Obstruction
OC Operating Certificate
OCA Obstacle Clearing Altitude
OCA Oceanic Control Area
OCC Occulting (light)
OCH Obstacle Clearance Height
OCNL Occasional, Occasionally
OCTA Outside Control Area
OCTR Outside Control Zone
OEI One Engine Inoperative
OEM Original Equipment Manufacturer
OFZ Obstacle Free Zone
OHD Overhead
OHS Occupation Health and Safety
OHSMS Occupational Health and Safety Management Systems
OIS Obstacle Identification Surface
OLC Office of Legal Counsel
OLDI On-line Data Interchange
OLS Obstacle Limitation Surface
OM Operations Manual
OM Outer Marker
OPA Opaque, white type of ice formation
OPC Office of Parliamentary Counsel
OPMET Operational Meteorological
OPN Operational Notification Message (message type designator)
OPN Open, Opening, Opened
OPR Operator, Operate, Operative, Operating, Operational
OPS Operations
OSIP Overhaul and Special Inspections Periods
OT Other Times
OTAC Overseas Territories Aviation Circulars
OTAR Overseas Territories Aviation Requirements
OTLK Outlook (used in Sigmet messages for volcanic ash and tropical cyclones)
OTP On Top
OUBD Outboard
OVC Overcast
OW Over Water

P.. Prohibited Area (followed by identification)
PA Precision Approach
PAL Pilot Activated Lighting
PANS Procedures for Air Navigation Services
PANS-OPS Procedures for Air Navigation Services - Aircraft Operations ICAO Doc 8168 Vol I and II
PAPI Precision Approach Path Indicator
PAR Precision Approach Radar
PARL Parallel
PATC Precision Approach Terrain Chart (followed by name/title)
PAX Passengers
PBM Power Plant Build-Up Manual
PC Personal Computer
PCATD Personal Computer-based Aviation Training Device
PCD Proceed, Proceeding
PCL Pilot Controlled Lighting
PCN Pavement classification number
PCT Practical consolidation training
PDC Pre-Departure Clearance
PDO Product distribution organisation
PDOP Positional Dilution of Precision
PDSE Pre-departure Service Check
PEC Pressure Error Correction
PERM Permanent
PFC Porous Friction Course
PFR Preferred Route
PH Public Holiday
PIB Pre-flight information bulletin
PIC Pilot-in-command
PICUS Pilot-in-Command Under Supervision
PIFR Private IFR rating
PILS Practice ILS
PIREP Pilot Reports
PJE Parachute Jumping Exercise
PL Ice Pellets
PLN Flight Plan
PLVL Present Level
PMP Primary Maintenance Process
PN Prior Notice Required
PNR Point of No Return
PO Dust Devils
POB Persons on Board
POH Pilot Operating Handbook
POSS Possible
PPI Plan Position Indicator
PPL Private Pilot Licence
PPR Prior Permission Required
PPS Precise Positioning Service
PPSN Present Position
PRD Prohibited, Restricted and Danger Areas
PRFG Aerodrome Partially Covered by Fog (MET code)
PRI Primary
PRKG Parking
PRM Precision Runway Monitoring
PRM Precision runway monitoring
PROB Probable, Probability
PROC Procedure
PROV Provisional
PS Plus
PSG Passing
PSN Position
PSP Pierced Steel Plank
PSR Primary Surveillance Radar
PSYS Pressure System(s)
PTBL Portable
PTN Procedure Turn
PTT Push To Talk
PVT Private
PWR Power

QDM Magnetic Heading (zero wind)
QDR Magnetic Bearing
QEC Quick Engine Change Unit
QFE An altimeter set to QFE will read zero when the aircraft is on the runway
QMS Quality Management System
QNH Altimeter subscale setting to obtain elevation or altitude
QTE True Bearing
QTG Qualification test guide
QUAD Quadrant

R Red
R Right (runway system identification)
R.... Restricted Area (followed by number)
R/T Radio Telephone
RA Rain
RA-Aus Recreational Aviation Australia
RAAA Recreational Aviation Association of Australia
RAAO Recreational Aviation Administrative Organisation
RAC Rules of the Air and Air Traffic Services
RAD Radius
RAeS Royal Aeronautical Society
RAFC Regional Area Forecast Centre
RAG Ragged
RAG Runway Arresting Gear
RAI Runway Alignment Indicator
RAIM Receiver Autonomous Integrity Monitoring
RAM Repair and Maintenance
RAPAC Regional Airspace Users Advisory Committee
RAPIC Radar Picture (MET)
RAS Radar Advisory Service
RASF Regional Aviation Safety Forum
RAT RAM Air Turbine
RCA Reach Cruising Altitude,
RCA Request For Corrective Action
RCC Rescue Coordination Centre
RCH Reach, Reaching
RCL Runway Centre Line
RCLL Runway Centre Line Lights
RCLM Runway Centre Line Marking
RDL Radial
RDO Radio
RDS Runway Distance Supplement
RE... Recent (used to qualify weather phenomena, eg RERA = recent rain)
REC Receive, Receiver, Received
REDL Runway Edge Lights
REF Reference to... Refer to...
REG Registration
RENL Runway End Lights
ReOC PRPA operator’s certificate
REP Report, Reported, Reporting, Reporting Point
RePL Remote pilot licence
REQ Request, Requested
RERTE Re-route
RES Reserve Fuel
RESA Runway end safety area
RESTR Restrictions
REV Review
RFACA Royal Federation of Aero Clubs of Australia
RFC Request for change
RFC Regional Forecasting Centre (Met)
RFFS Rescue and Fire Fighting Services
RH Radio Height
RHC Right-hand Circuit
RIF Reclearance in Flight
RIFTO Restricted Instrument Flight Take-off
RIS Regulation Impact Statement
RIS Radar information service
RL Report Leaving
RLA Relay to
RLLS Runway Lead-in Lighting
RMIT Royal Melbourne Institute of Technology
RMK Remark(s)
RMS Root Mean Square
RNAV Area navigation
RNP Required navigation performance
RO Registered operator
ROBEX Regional OPMET Bulletin Exchanges
ROC Rate of Climb
ROD Rate of Descent
ROFOR Route Forecast (in aeronautical meteorological code)
RPA Remotely piloted aircraft
RPA Rules and practices for aerodromes
RPAS Remotely piloted aircraft system
RPI Radar Position Indicator
RPI Regulatory Performance Indicator
RPI Runway Point of Intercept
RPL Recognition of prior learning
RPM Revolutions Per Minute
RPS Remote pilot station
RPT Regular public transport
RQ Require(d)
RQMNTS Requirements
RR Report Reaching
RRM Routine Reportable Matters
RSC Rescue Sub-Centre
RSCD Runway Surface Condition
RSP Responder Beacon
RSR En route Surveillance Radar
RTB Return to Base
RTCA Radio Technical Commission for Aeronautics
RTE Route
RTF Radio Telephone
RTHL Runway Threshold Light(s)
RTIL Runway Threshold Identification Lights
RTN Return, Returned, Returning
RTO Rejected take-off
RTO Registered training organisation
RTS Return to Service
RTZL Runway Touchdown Zone Light(s)
RVR Runway visual range
RVSM Reduced Vertical Separation Minimum
RWS Runway Strip
RWY Runway

S South, South Latitude
S-I Straight-In
S/E Single-engine
SA Sand
SA Selective Availability
SA Situation Awareness
SAAA Sport Aircraft Association of Australia
SAL Supplementary Airline Licence
SALR Saturated Adiabatic Lapse Rate
SALS Simple Approach Lighting System
SAR Search and Rescue
SARPs Standards and Recommended Practices
SARTIME Time search action required
SARWATCH Search and Rescue Watch
SATCOM Satellite Communication
SB Service Bulletin
SB Southbound
SBAS Satellite Based Augmentation System
SC Stratocumulus
SCC Standards Consultative Committee
SCP Safety Critical Personnel
SCT Scattered (meteorological)
SDBY Standby
SDC Standard Departure Clearance
SDR Service difficulty report
SE South East
SEA Sea (used in connection with sea-surface temperature and state of the sea)
SEACO Single engine aircraft only
SEC Seconds
SECN Section
SECT Sector
SELCAL Selective Calling System
SER Service, Servicing, Served
SEV Severe (used eg to qualify icing and turbulence report)
SFC Surface
SFL Sequenced Flashing Lights
SG Snow Grains
SH... Showers (followed by RA=rain, SN=snow, PL=ice pellets, GR=hail, GS=small hail and/or snow pellets or combinations thereof, eg, SHRASN = showers of rain and snow)
SHF Super High Frequency (3,000 to 30,000 MHZ)
SHP Shaft Horse Power
SID Standard instrument departure
SIF Selective Identification
SIG Significant
SIGMET Information concerning en route weather phenomena which may affect the safety of aircraft operations
SIL Service Information Letter
SIMUL Simultaneous, or Simultaneously
SKC Sky Clear
SKED Schedule, Scheduled
SL Service Letter
SLP Speed Limiting Point
SLW Slow, Slowly
SM Safety Manager
SMC Surface Movement Control
SMR Surface Movement Radar
SMS Safety management system
SN Snow
SNOWTAM A special series NOTAM notifying the presence or removal of hazardous conditions due to snow, ice, slush or standing water associated with snow, slush and ice on the movement area
SOC Start of Climb
SOE Schedule of experience
SOM (SoM) System of Maintenance
SOPs Standard Operating Procedures
SOR Summary of responses
SOT Start of TORA (take-off)
SP Single Pilot
SPA Sport Aviation
SPECI Aviation Special Weather (in aeronautical meteorological code)
SPFIB Specific Preflight Information Bulletin
SPOT Spotwind
SPS Standard Positioning Service
SQ Squall
SR Sunrise
SRB Safety Review Board
SRD Standard Radar Departure
SRG Short Range
SRM Structural Repair Manual
SRR Search and Rescue Region
SRY Secondary
SS Sandstorm
SS Sunset
SSB Single Sideband
SSCRO Senate Standing Committee on Regulations and Ordinances
SSE South South-East
SSI Structural Significant Item
SSM System Schematics Manual
SSR Secondary Surveillance Radar
SST Supersonic Transport
SSW South South-West
ST Stratus
STA Straight in Approach
STAR Standard Arrival Route
STAR Standard instrumental arrival
STARs Standard terminal arrival routes
STC Supplemental Type Certificate
STD Synthetic training device
STD Standard
STF Stratiform
STN Station
STNR Stationary
STODA Supplementary Take-off Distance
STOL Short Take-off and Landing
STS Status
STWL Stopway Light(s)
SUBJ Subject to
SUP Supplement (AIP Supplement)
SUPPS Regional Supplementary Procedures
SVCBL Serviceable
SVY Survey Operations
SW South-West
SWS Soft Wet Surface
SWY Stopway

T Temperature
T-VASIS T'Visual Approach Slope Indicator System (pronounced 'TEE-VAR-SIS')
TA Transition Altitude
TA Traffic advisory
TAAATS The Australian Advanced Air Traffic System
TAAM Airservices Australia's Total Airspace Airport and Aerodrome Modeller
TAC Terminal Area Chart
TACAN Tactical Air Navigation Aid
TAF Aerodrome Forecast
TAF Terminal Area Forecast
TAIL Tailwind
TAR Terminal Area Surveillance Area
TAS True Airspeed
TAT Terminal Area Thunderstorm Service (meteorological term)
TAWS Terrain awareness and warning system
TAWS-B+ system A terrain awareness and warning system that is equipped with a visual display and complies with the requirements for Class B equipment expressed in TSO-C151, TSO-C151a or TSO-C151b.
TAX Taxiing, Taxi
TBA To be advised
TBO Time Between Overhauls
TC Type Certificate
TC Tropical Cyclone
TCAC Tropical Cyclone Advisory Centre
TCAS Traffic alert and collision avoidance system
TCDS Type certificate data sheet
TCH Threshold Crossing Height
TCO Training and Checking Organisation
TCTA Trans-continental Control Area
TCU Towering Cumulus (met)
TDO Tornado
TDZ Touchdown Zone
TECR Technical Reason
TEL Telephone
TEM (Illustrated) Tool And Equipment Manual
TEM Threat and Error Management
TEMPO Temporary, Temporarily (meteorologically)
TERPs Terminal and En-route procedures
TFC Traffic
TFR Terrain Following Radar (by the MIL)
TGL Touch & Go Landing
TGS Taxiing Guidance System
THR Threshold
THRU Through
TIBA Traffic Information Broadcasts by Aircraft
TIL Until
TIP Until Past (place)
TIS Time in service
TKOF Take-off
TLOF Touchdown and lift-off area
TLS Transponder Landing System
TLW Time Limited WIP (work in progress)
TMA Terminal Control Area
TMG Track Made Good
TNA Training Needs Analysis
TNA Turn Altitude
TNH Turn Height
TNS Transitional Surface
TO Takeoff
TOC Top of Climb
TODA Take-off distance available
TOP Cloud Top
TORA Take-off run available
TOT Turbine Outlet Temperature
TP Turning Point
TR Track
TRA Temporary Reserved Airspace
TRAN Transition
TRANS Transmits, Transmitter
Trike A manned, powered hang-glider
TRL Transition Level
TROP Tropopause
TS... Thunderstorm (followed by RA=rain, SN=snow, PE=ice pellets, GR=hail, GS=small hail and/or snow pellets or combinations thereof, eg TSRASN = thunderstorm with rain and snow)
TSI Time Since Installation
TSO Technical Standard Order
TSO Time Since Overhaul
TTF Trend Type Forecast
TTMRA Trans Tasman Mutual Recognition Agreement
TURB Turbulence
TWR Aerodrome Control Tower, Aerodrome Control
TWY Taxiway
TWYL Taxiway Link
TYP Type of Aircraft
TYPH Typhoon

U/S Unserviceable
UAB Until Advised By
UAS Unmanned aerial system (UAV/RPAS)
UAV Unmanned aerial vehicles
UDF UHF Direction Finding Stations
UFIT Uncontrolled Flight Into Terrain
UFN Until Further Notice
UHDT Unable Higher Due Traffic
UHF Ultra High Frequency (300 to 3,000 MHZ)
UIR Upper Flight Information Region
UK United Kingdom
UL Upper Limits
UNA Unable
UNAP Unable to Approve
UNICOM Universal Communications
UNL Unlimited
UNLC Unlicensed
UNREL Unreliable
UOC Unmanned operating certificate
US FAR Federal Aviation Regulations (of the USA)
USA United States of America
UTA Upper Control Area
UTC Coordinated Universal Time

V Velocity
V1 Take-off Decision Speed
V2 Take-off Safety Speed (Applicable to Larger Multi-engine Aircraft)
VA Volcanic Ash
VA Maximum Manoeuvring Speed
VAA-H Visual Approach Area - Helicopter
VAAC Volcanic Ash Advisory Centre
VAC Visual Approach Chart (followed by name/title)
VAL In Valleys
VAR Magnetic Variation
VASIS Visual Approach Slope Indicator System
VC Vicinity of the aerodrome (followed by FG=fog, FC=funnel cloud, PO=dust/sand whirls, BLDU=blowing dust, BLSA=blowing sand or BLSN=blowing snow; eg, VCFG=vicinity fog
VCY Vicinity
VDF VHF Direction Finding Station
VEC Visual En-route Chart
VER Vertical
VFE Flap Extension Speed
VFR Visual flight rules
VHF Very High Frequency (30 to 300 MHZ)
VHFCOM Very High Frequency Communications
VIA By way of...
VIMD Maximum Drag Speed
VIP Very Important Person
VIS Visibility
VLE Maximum Speed with Landing Gear Extended
VLF Very Low Frequency (3 to 30 KHZ)
VLJ Very Light Jet
VLO Landing Gear Operating
VLO2 Landing Gear Operation Down
VLOS Visual line of sight
VLR Very Long Range
VMAN Visual Manoeuvre Speed
VMC Visual Meteorological Conditions
VMC Minimum Control Speed
VMCA Minimum Control Airspeed Airborne (Red line speed)
VMCG Minimum Control Airspeed on the Ground
VMO Maximum Structural Cruising Speed
VNAV Vertical Navigation
VNE Never Exceed Speed
VNO Normal Operating Speed
VOLMET Meteorological Information for Aircraft in Flight
VOR VHF Omni-directional Radio Range (OMNI)
VP Variable Pitch Propellers
VR The speed at which the aircraft is rotated to lift off from the runway
VRB Variable
VSI Vertical Speed Indicator
VSI Clean Stall Speed
VSL Vertical speed limit
VSO Stalling speed, minimum steady flight speed in the landing configuration
VSO Stall speed with undercarriage and flap selected
VSSE Safe single-engine Speed
VTC Visual Terminal Chart
VTOL Vertical take-off and landing
VTOSS Take-off Safely Speed
VX Best Angle of Climb Speed
VXSE Best Single-engine Angle of Climb Speed
Vy Best Rate of Climb Speed
VYSE Best Single-engine Rate of Climb Speed (Blue line speed)

W Watt
W West, West Longitude
W White
W/V Wind Velocity
WAAS Wide Area Augmentation System
WAC World Aeronautical Chart ICAO 1:1,000,000 (followed by name/title)
WAFC World Area Forecast Centre
WAFS World Area Forecast System
WATIR Weather and Terminal Information Reciter
WATOG World Airlines Technical Operations Glossary
WB Westbound
WBM Weight And Balance Manual
WDI Wind Direction Indicator
WDSPR Widespread
WED Wednesday
WEF With Effect From, Effective From
WGS-84 World Geodetic System 1984
WI Within
WID Width
WIE With Immediate Effect, Effective Immediately
WILCO Will Comply
WIND Wind (used in connection with direction and speed) WINTEM Forecast upper wind and temperature at specified points (in aeronautical met code)
WIP Work in Progress
WKN Weaken, Weakening
WM Wiring Manual
WMO World Meteorological Organisation
WNW West North-West
WO Without
WS Wind Shear
WSW West South-West
WT Weight
WTSPT Water Spout
WWW World Wide Web
WX Weather

X Cross
XBAR Crossbar (of approach lighting system)
XNG Crossing
XPDR Transponder
XS Atmospherics
XSEC Extra Section

Y Yellow
YCZ Yellow Caution Zone
YR Your/s

Z Coordinated Universal Time (in meteorological messages)