ABBREVIATIONS USED IN PUBLICATIONSAbbreviations marked by an asterisk (*) are either different from or not contained in Doc 8400. These shall not be used in .(†) – when radiotelephony is used, the abbreviations and terms are transmitted as spoken words(‡) – when radiotelephony is used, the abbreviations and terms are transmitted using the individual letters in non-phonetic form. AAmberA/AAir-to-airA/GAir-to-groundAAA(or AAB, AAC...etc., in sequence) Amended meteorological message (message type designator)AALAbove aerodrome levelABMAbeamABNAerodrome beaconABTAboutABVAboveACAltocumulusACAS†Airborne collision avoidance systemACC‡Area control centre or area controlACCIDNotification of an aircraft accidentACFTAircraftACKAcknowledgeACLAltimeter check locationACNAircraft classification numberACPAcceptance (message type designator)ACPTAccept or acceptedACTActive or activated or activityADAerodromeADAAdvisory areaADDNAddition or additionalADF‡Automatic direction-finding equipmentADIZ†(to be pronounced "AY-DIZ") Air defence identification zoneADJAdjacentADRAdvisory routeADSAutomatic dependent surveillanceADSUAutomatic dependent surveillance unitADVSAdvisory serviceADZAdviseAESAircraft earth stationAFILFlight plan filed in the airAFISAerodrome flight information serviceAFMYes or affirm or affirmative or that is correctAFSAeronautical fixed serviceAFTAfter... (time or place)AGAAerodromes, air routes and ground aidsAGLAbove ground levelAICAeronautical information circularAIPAeronautical information publicationAIRACAeronautical information regulation and controlAIREP†Air-reportAIRMET†Information concerning en-route weather phenomena which may affect the safety of low-level aircraft operationsAISAeronautical information servicesALAAlighting areaALERFA†Alert phaseALRAlerting (message type designator)ALRSAlerting serviceALSApproach lighting systemALTAltitudeALTNAlternate or alternating (light alternates in colour)ALTNAlternate (aerodrome)AMAArea minimum altitudeAMCAirspace management cellAMDAmend or amended (used to indicate amended meteorological message; message type designator)AMDTAmendment (AIP amendment)AMHSAeronautical message handling systemAMSAeronautical mobile serviceAMSLAbove mean sea levelAMSSAeronautical mobile satellite serviceANSAnswerAOCAerodrome obstacle chartAORArea of responsibilityAPAirportAPCHApproachAPPApproach control office or approach control or approach control serviceAPRAprilAPRXApproximate or approximatelyAPSGAfter passingARCCAeronautical rescue coordination centreARFORArea forecast (in aeronautical meteorological code)ARNGArrangeAROAir traffic services reporting officeARPAerodrome reference pointARPAir-report (message type designator)ARQAutomatic error correctionARRArrive or arrivalARRArrival (message type designator)ARSTArresting (specify (part of) aircraft arresting equipment)ASAltostratusASAPAs soon as possibleASCAscend or ascending toASDAAccelerate-stop distance availableASPHAsphaltAT...At (followed by time at which weather change is forecast to occur)ATA‡Actual time of arrivalATC‡Air traffic control (in general)ATD‡Actual time of departureATFMAir traffic flow managementATIS†Automatic terminal information serviceATMAir traffic managementATNAeronautical telecommunication networkATPAt... (time or place)ATSAir traffic servicesATTNAttentionATZAerodrome traffic zoneAUGAugustAUTHAuthorized or authorizationAUWAll-up weightAUXAuxiliaryAVASISAbbreviated visual approach slope indicator systemAVBLAvailable or availabilityAVGAverageAVGAS†Aviation gasolineAWOSAutomated weather observing systemAWTAAdvise at what time ableAWYAirwayAZMAzimuthBBlueBABraking actionBASE†Cloud baseBCFGFog patchesBCNBeacon (aeronautical ground light)BCSTBroadcastBDRYBoundaryBECMGBecomingBFRBeforeBKNBrokenBL...Blowing (followed by DU = dust, SA = sand or SN = snow)BLDGBuildingBLOBelow cloudsBLWBelow...BOMBBombingBRMistBRFShort (used to indicate the type of approach desired or required)BRGBearingBRKGBrakingB-RNAVBasic area navigationBSCommercial broadcasting stationBTLBetween layersBTNBetweenCCentre (runway identification)CDegrees Celsius (Centigrade)CChartCACourse to an altitudeCATCategoryCATClear air turbulenceCAVOK†(to be pronounced "KAV-OH-KAY") Visibility, cloud and present weather better than prescribed values or conditionsCB‡(to be pronounced "CEE BEE") CumulonimbusCCCirrocumulusCCA(or CCB, CCC...etc., in sequence) Corrected meteorological message type designator)CDCandelaCDNCo-ordination (message type designator)CDRConditional routeCFChange frequency to...CFCourse to a fixCGLCircling guidance light(s)CICirrusCIDIN†Common ICAO data interchange networkCIT Near or over large townsCIVCivilCKCheckCLCentre lineCLAClear type of ice formationCLBRCalibrationCLDCloudCLGCallingCLRClear(s) or cleared to... or clearanceCLSDClose or closed or closingCMCentimetreCMBClimb to or climbing toCMPLCompletion or completed or completeCNLCancel or cancelledCNLFlight plan cancellation (message type designator)CNSCommunications, navigation and surveillanceCOMCommunicationsCONCConcreteCONDConditionCONSContinuousCONSTConstruction or constructedCONTContinue(s) or continuedCOORCo-ordinationCOPChange-over pointCORCorrect or correction or corrected (used to indicate corrected meteorological message; (message type designator)COTAt the coastCOVCover or covered or coveringCPDLC‡Controller-pilot data link communicationsCPLCurrent flight plan (message type designator)CRZCruiseCSCirrostratusCTAControl areaCTAMClimb to and maintainCTCContactCTLControlCTNCautionCTOT Calculated Take-Off TimeCTRControl zoneCUCumulusCUFCumuliformCUSTCustomsCWContinuous waveCWYClearwayCHChannelCHGModification (message type designator)D...Danger area (followed by identification)DDownward (tendency in RVR during previous 10 minutes)DADecision altitudeD-ATIS†(to be pronounced “DEE-ATIS”) Data link automatic terminal information serviceDCDDouble channel duplexDCKGDockingDCSDouble channel simplexDCTDirect (in relation to flight plan clearances and type of approach)DECDecemberDEGDegreesDENEBFog dispersal operationsDEPDepart or departureDEPDeparture (message type designator)DESDescend to… or descending to…DESTDestinationDETRESFA†Distress phaseDEVDeviation or deviatingDF Direct to a fixDFTIDistance from touchdown indicatorDHDecision heightDIFDiffuseDISTDistanceDIVDivert or divertingDLADelay (message type designator)DLADelay or delayedDME‡Distance measuring equipmentDNGDanger or dangerousDOMDomesticDPDew point temperatureDPTDepthDRDead reckoningDRLow drifting (followed by DU = dust, SA = sand or SN = snow)DRGDuringDSDuststormDTAMDescend to and maintainDTGDate-time groupDTHRDisplaced runway thresholdDTRTDeteriorate or deterioratingDTWDual tandem wheelsDUDustDUCDense upper cloudDURDurationDVORDoppler VORDWDual wheelsDZDrizzleEEast or eastern longitudeEATExpected approach timeEBEastboundEETEstimated elapsed timeEFCExpect further clearanceEHFExtremely high frequency (30 000 to 300 000 MHZ)ELBA†Emergency location beacon-aircraftELEVElevationELRExtra long rangeEMEmissionEMBDEmbedded in layer (to indicate cumulonimbus embedded in layers of other clouds)EMERGEmergencyENDStop-end (related to RVR)ENEEast north eastENGEngineENREn routeEOBTEstimated off-block timeEQPTEquipmentERHere... or herewithESEEast south eastESTEstimate or estimated or estimate (message type designator)ETA‡Estimated time of arrival or estimating arrivalETD‡Estimated time of departure or estimating departureETOEstimated time over significant pointEUREuropean (ICAO region)EVEveryEXCExceptEXERExercises or exercising or to exerciseEXPExpect or expected or expectingEXTDExtend or extendingFFixedFABFunctional Airspace BlockFACFacilitiesFAFFinal approach fixFALFacilitation of international air transportFAPFinal approach pointFATOFinal approach and take-off areaFAXFacsimile transmissionFBLLight (used to indicate the intensity of weather phenomena, interference or static reports, e.g. FBL RA = light rain)FBZFlight plan buffer zoneFCFunnel cloud (tornado or water spout)FCSTForecastFCTFriction coefficientFEBFebruaryFGFogFICFlight information centreFIR‡Flight information regionFISFlight information serviceFISAAutomated flight information serviceFLFlight levelFLDFieldFLGFlashingFLRFlaresFLTFlightFLTCKFlight checkFLUCFluctuating or fluctuation or fluctuatedFLWFollow(s) or followingFLYFly or flyingFMFromFM...From (followed by time weather change is forecast to begin)FMS‡Flight management systemFNAFinal approachFPLFiled flight plan (message type designator)FPMFeet per minuteFPRFlight plan routeFRFuel remainingFRAFree Route AirspaceFREQFrequencyFRIFridayFRNGFiringFRONT†Front (relating to weather)FRQFrequentFSLFull stop landingFSSFlight service stationFSTFirstFTFeet (dimensional unit)FUSmokeFZFreezingFZDZFreezing drizzleFZFGFreezing fogFZRAFreezing rainGGreenG/AGround-to-airG/A/GGround-to-air and air-to-groundGAMETArea forecast for low-level flightsGATGeneral air trafficGBAS†(to be pronounced “GEE-BAS”) Ground-based augmentation systemGENGeneralGEOGeographic or trueGESGround earth stationGLDGliderGNDGroundGNDCKGround checkGNSS‡Global navigation satellite systemGPGlide pathGPS‡Global position systemGRHailGRASSGrass landing areaGRIBProcessed meteorological data in the form of grid point values (in meteorological code)GRVLGravelGSGround speedGSSmall hail and/or snow pelletsGUNDGeoid undulationH24Continuous day and night serviceHAPIHelicopter approach path indicatorHBNHazard beaconHDFHigh frequency direction-finding stationHDGHeadingHELHelicopterHF‡High frequency (3 000 to 30 000 KHZ)HGTHeight or height aboveHIRLHigh intensity runway lightsHJSunrise to sunsetHLDGHoldingHMHolding/racetrackHNSunset to sunriseHOService available to meet operational requirementsHOLHolidayHOSPHospital aircraftHPAHectopascalHRHoursHSService available during hours of scheduled operationsHURCNHurricaneHVDFHigh and very high frequency direction-finding station (at the same location)HVYHeavyHVYHeavy (used to indicate the intensity of weather phenomena, e.g. HVY RA = heavy rain)HXNo specific working hoursHYRHigherHZHertz (cycle per second)HZHazeIACInstrument approach chartIAFInitial approach fixIAOIn and out of cloudsIAPInstrument approach procedureIARIntersection of air routesIASIndicated air speedIBNIdentification beaconICDiamond dust (very small ice crystals in suspension)ICAOInternational Civil Aviation OrganizationICEIcingIDIdentifier or identifyIDENT†IdentificationIFIntermediate approach fixIFFIdentification friend/foeIFPSIntegrated Initial Flight Plan Processing SystemIFR‡Instrument flight rulesIGAInternational general aviationIHPIntermediate holding positionILS‡Instrument landing systemIMInner markerIMC‡Instrument meteorological conditionsIMGImmigrationIMPRImprove or improvingIMTImmediate or immediatelyINAInitial approachINBDInboundINCIn cloudINCERFA†Uncertainty phaseINFO†InformationINOPInoperativeINPIf not possibleINPRIn progressINSInertial navigation systemINSTLInstall or installed or installationINSTRInstrumentINTIntersectionINTLInternationalINTRGInterrogatorINTRPInterrupt or interruption or interruptedINTSFIntensify or intensifyingINTSTIntensityIRIce on runwayIRSInertial reference systemISAInternational standard atmosphereISOLIsolatedJANJanuaryJTSTJet streamJULJulyJUNJuneKGKilogramsKHZKilohertzKMKilometresKMHKilometres per hourKOPAir ForceKPAKilopascalKTKnotsKWKilowattsLLeft (runway identification)LLocator (see LM, LO)LAMLogical acknowledgement (message type designator)LANInlandLATLatitudeLDALanding distance availableLDAHLanding distance available, helicopterLDGLandingLDILanding direction indicatorLENLengthLFLow frequency (30 to 300 KHZ)LGTLight or lightingLGTDLightedLIHLight intensity highLILLight intensity lowLIMLight intensity mediumLMLocator, middleLMTLocal mean timeLNGLong (used to indicate the type of approach desired or required)LOLocator, outerLOCLocal or locally or location or locatedLOCLocalizerLONGLongitudeLORAN†LORAN (long range air navigation system)LRGLong rangeLSQLine squallLTDLimitedLTTLandline teletypewriterLVLight and variable (relating to wind)LVELeave or leavingLVLLevelLVPLow visibility proceduresLYRLayer or layeredMMach number (followed by figures)MMetres (preceded by figures)MAAMaximum authorized altitudeMAGMagneticMAHFMissed approach holding fixMAINTMaintenanceMAPAeronautical maps and chartsMAPTMissed approach pointMARAt seaMARMarchMATFMissed approach turning fixMAXMaximumMAYMayMCAMinimum crossing altitudeMCWModulated continuous waveMDAMinimum descent altitudeMDFMedium frequency direction-finding stationMDHMinimum descent heightMEAMinimum en-route altitudeMEHTMinimum eye height over threshold (for visual approach slope indicator systems)MET†Meteorological or meteorologyMETAR†Aviation routine weather report (in aeronautical meteorological code)MFMedium frequency (300 to 3 000 KHZ)MHDFMedium and high frequency direction-finding stations (at the same location)MHVDFMedium, high and very high frequency direction-finding stations (at the same location)MHZMegahertzMIDMid-point (related to RVR)MIDMiddle EastMIFGShallow fogMILMilitaryMINMinutesMKRMarker radio beaconMLS‡Microwave landing systemMNMMinimumMNPSMinimum navigation performance specificationsMNTMonitor or monitoring or monitoredMNTNMaintainMOAMilitary operating areaMOCMinimum obstacle clearance (required)MODModerate (used to indicate the intensity of weather phenomena, interference or static reports, e.g. MOD RA = moderate rain)MONAbove mountainsMONMondayMOVMove or moving or movementMPSMetres per secondMRAMinimum reception altitudeMRGMedium rangeMRPATS/MET reporting pointMSMinusMSAMinimum sector altitudeMSGMessageMSLMean sea levelMSSRMonopulse secondary surveillance radarMTMountainMTUMetric unitsMTWMountain wavesMVDFMedium and very high frequency direction finding stations (at the same location)MWOMeteorological watch officeMXMixed type of ice formation (white and clear)NNorth or northern latitudeNNo distinct tendency (in RVR during previous 10 minutes)NATNorth AtlanticNAVNavigationNBNorthboundNBFRNot beforeNCNo changeNDB‡Non directional radio beaconNENorth-eastNEBNorth-eastboundNEGNo or negative or permission not granted or that is not correctNGTNightNIL†None or I have nothing to send to youNMNautical milesNMNetwork Manager/ManagementNMLNormalNMOCNetwork Manager Operations CentreNNENorth north eastNNWNorth north westNOFInternational NOTAM officeNOSIG†No significant change (used in trend-type landing forecasts)NOTAM†Notice containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operationsNOVNovemberNPANon-precision approachNPZNo planning zoneNRNumberNRHNo reply heardNSNimbostratusNSCNil significant cloudNSWNil significant weatherNWNorth-westNWBNorth-westboundNXTNextO/ROn requestOACOceanic area control centreOASObstacle assessment surfaceOATOperational air trafficOBSObserve or observed or observationOBSCObscure or obscured or obscuringOBSTObstacleOCAObstacle clearance altitudeOCAOceanic control areaOCCOcculting (light)OCNLOccasional or occasionallyOCSObstacle clearance surfaceOCTOctoberOHDOverheadOCHObstacle clearance heightOMOuter markerOPAOpaque, white type of ice formationOPMET†Operational meteorological (information)OPNOpen or opening or openedOPROperator or operate or operative or operating or operationalOPS†OperationsORDOrderOSVOcean station vesselOTLKOutlook (used in SIGMET messages for volcanic ash and tropical cyclones)OTPOn topOTSOrganized track systemOUBDOutboundOVCOvercastPPersonal consultationP...Prohibited area (followed by identification)PAPrecision approachPALSPrecision approach lighting system (specify category)PANSProcedures for air navigation servicesPAPI†Precision approach path indicatorPARLParallelPAXPassenger(s)PCDProceed or proceedingPCNPavement classification numberPCRPavement classification ratingPDGProcedure design gradientPERPerformancePERMPermanentPIBPre-flight information bulletinPJEParachute jumping exercisePLAbbreviated plain language textsPLIce pelletsPLAPractice low approachPLNFlight planPLVLPresent levelPNPrior notice requiredPNRPoint of no returnPODust devilsPOBPersons on boardPOSSPossiblePPIPlan position indicatorPPRPrior permission requiredPPSNPresent positionPRIPrimaryPRKGParkingP-RNAVPrecision area navigationPROB†ProbabilityPROCProcedurePROVProvisionalPSPlusPSGPassingPSNPositionPSPPierced steel plankPSR‡Primary surveillance radarPTNProcedure turnPTSPolar track structurePWRPowerQBICompulsory IFR flightQDM‡Magnetic heading (zero wind)QDRMagnetic bearingQFE‡Atmospheric pressure at aerodrome elevation (or at runway threshold)QFUMagnetic orientation of runwayQNH‡Altimeter sub-scale setting to obtain elevation when on the groundQTETrue bearingQUADQuadrantRRedRRight (runway identification)R...Restricted area (followed by identification)RARainRACRules of the air and air traffic servicesRADRoute Availability DocumentRAFCRegional area forecast centreRAGRaggedRAGRunway arresting gearRBRescue boatRCAReach cruising altitudeRCCRescue co-ordination centreRCFRadiocommunication failure (message type designator)RCLRunway centre lineRCLLRunway centre line light(s)RCLMRunway centre line markingsRCLRReclearedRDHReference datum heightRDLRadialRDORadioRE...Recent (used to qualify weather phenomena, e.g. RERA = recent rain)RECReceive or receiverREDLRunway edge light(s)REFReference to ... or refer to ...REGRegistrationRENLRunway end light(s)REPReport or reporting pointREQRequest or requestedRERTERerouteRESARunway end safety areaRGRange (lights)RCHReach or reachingRIFReclearance in flightRITERight (direction of turn)RLReport leavingRLRunway lightsRLARelay toRLCERequest level change en routeRLLSRunway lead-in lighting systemRLNARequest level not availableRMKRemarkRMZRadio mandatory zoneRNAV†(to be pronounced "AR-NAV") Area navigationRNGRadio rangeRNP‡Required navigation performanceROBEX†Regional OPMET bulletin exchange (scheme)ROCRate of climbRODRate of descentROFORRoute forecast (in meteorological code)RONReceiving onlyRPIReference path identifierRPLRepetitive flight planRPLCReplace or replacedRPSRadar position symbolRQMNTSRequirementsRQPRequest flight plan (message type designator)RQSRequest supplementary flight plan (message type designator)RRReport reachingRRA(or RRB, RRC... etc., in sequence) Delayed meteorological message type designator)RSCRescue sub-centreRSCDRunway surface conditionRSPResponder beaconRSREn-route surveillance radarRTDDelayed (used to indicate delayed meteorological message; message type designator)RTERouteRTFRadiotelephoneRTGRadiotelegraphRTHLRunway threshold light(s)RTILRunway threshold identification lightsRTNReturn or returned or returningRTODAHRejected take-off distance available, helicopterRTSReturn to serviceRTTRadioteletypewriterRTZLRunway touchdown zone light(s)RUTStandard regional route transmitting frequenciesRVRescue vesselRVR‡Runway visual rangeRVSM‡Reduced vertical separation minimumRWYRunwaySSurface analysis (current chart)SSouth or southern latitudeSASandSALSSimple approach lighting systemSANSanitarySARSearch and rescueSARPSStandards and Recommended Practices (ICAO)SATSaturdaySATCOM†Satellite communicationSBSouthboundSCStratocumulusSCTScatteredSDBYStand bySDFStep down fixSESouth-eastSEBSouth-eastboundSECSecondsSECTSectorSELCAL†Selective calling systemSEPSeptemberSERService or servicing or servedSEVSevere (used e.g. to qualify icing and turbulence reports)SFCSurfaceSGSnow grainsSGLSignalSGZSpecial gliders zoneSH...Showers (followed by RA = rain, SN = snow, PL = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. SHRASN = showers of rain and snow)SHFSuper high frequency (3 000 to 30 000 MHZ)SID†Standard instrument departureSIFSelective identification featureSIGSignificantSIGMET†Information concerning en-route weather and other phenomena in the atmosphere that may affect the safety of aircraft operationsSIGWXSignificant weatherSIMULSimultaneous or simultaneouslySIWLSingle isolated wheel loadSKCSky clearSKEDSchedule or scheduledSLPSpeed limiting pointSLWSlowSMCSurface movement controlSMRSurface movement radarSNSnowSNOWTAM†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, by means of a specific formatSOCStart of climbSPECI†Aerodrome special meteorological report (in meteorological code)SPECIAL†Special meteorological report (in abbreviated plain language)SPLSupplementary flight plan (message type designator)SPOT†Spot windSQSquallSRSunriseSRASurveillance radar approachSRESurveillance radar element of precision approach radar systemSRGShort rangeSRRSearch and rescue regionSRYSecondarySSSandstormSSSunsetSSESouth south eastSSR‡Secondary surveillance radarSSTSupersonic transportSSWSouth south westSTStratusSTAStraight in approachSTAR†Standard instrument arrivalSTDStandardSTFStratiformSTNStationSTNRStationarySTOLShort take-off and landingSTSStatusSTWLStopway light(s)SUA Special use airspaceSUBJSubject toSUNSundaySUPSupplement (AIP Supplement)SUPPSRegional supplementary proceduresSVCService (message type only)SVCBLServiceableSWSouth-westSWBSouth-westboundSWYStopwayTTemperatureT(...T)True (preceded by a bearing to indicate reference to True North)TATransition altitudeTAATerminal arrival altitudeTACAN†UHF tactical air navigation aidTAF†Aerodrome forecast (in meteorological code)TAIL†Tail windTARTerminal area surveillance radarTASTrue airspeedTAXTaxiing or taxiTBTabular formsTCTropical cycloneTCUTowering cumulusTDOTornadoTDZTouchdown zoneTECRTechnical reasonTELTelephoneTEMPO†Temporary or temporarilyTENDTrend forecastTFTrack to fixTFCTrafficTGLTemporary Guidance LeafletTGLTouch-and-go landingTGMTemporary Guidance MaterialTGSTaxiing guidance systemTHRThresholdTHRUThroughTHUThursdayTCHThreshold crossing heightTIATraffic information areaTIL†UntilTIPUntil past ... (place)TIZTraffic information zoneTKOFTake-offTL...Till (followed by time by which weather change is forecast to end)TLOFTouchdown and lift-off areaTMA‡Terminal control areaTNATurn altitudeTNHTurn heightTOTo ... (place)TOCTop of climbTODATake-off distance availableTODAHTake-off distance available, helicopterTOP†Cloud topTORATake-off run availableTPTurning pointTRTrackTRATemporary reserved airspaceTRANSTransmits or transmitterTREND†Trend forecastTRLTransition levelTROPTropopauseTSThunderstorm (in aerodrome reports and forecasts, TS used alone means thunder heard but no precipitation at the aerodrome)TS...Thunderstorm (followed by RA = rain, SN = snow, PL = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. TSRASN = thunderstorm with rain and snow)TSATemporary segregated areaTTTeletypewriterTUETuesdayTURBTurbulenceTVORTerminal VORTWRAerodrome control tower or aerodrome controlTWYTaxiwayTWYLTaxiway-linkTYPType of aircraftTYPHTyphoonUUpward (tendency in RVR during previous 10 minutes)U/SUnserviceableUABUntil advised by...UACUpper area control centreUARUpper air routeUDFUltra high frequency direction-finding stationUFNUntil further noticeUHDTUnable higher due trafficUHF‡Ultra high frequency (300 - 3 000 MHZ)UICUpper information centreUIR‡Upper flight information regionULRUltra long rangeUNAUnableUNAPUnable to approveUNLUnlimitedUNRELUnreliableUTAUpper control areaUTC‡Coordinated Universal TimeVAVolcanic ashVACVisual approach chartVALIn valleysVANRunway control vanVARMagnetic variationVASISVisual approach slope indicator systemVCVicinity of the aerodrome (followed by FG = fog, FC = funnel cloud, SH = showers, PO = dust/sand whirls, BLDU = blowing dust, BLSA = blowing sand or BLSN = blowing snow, e.g. VCFG = vicinity fog)VCYVicinityVDFVery high frequency direction-finding stationVERVerticalVFR‡Visual flight rulesVHF‡Very high frequency (30-300 MHZ)VIABy way of...VIP‡Very important personVISVisibilityVLFVery low frequency (3 to 30 KHZ)VLRVery long rangeVMC‡Visual meteorological conditionsVOLMET†Meteorological information for aircraft in flightVOR‡VHF omnidirectional radio rangeVORTAC†VOR and TACAN combinationVOTVOR airborne equipment test facilityVRBVariableVSABy visual reference to the groundVSATState Border Guard ServiceVSPVertical speedVTOLVertical take-off and landingWWest or western longitudeWWhiteWACWorld aeronautical chart - ICAO 1:1 000 000WAFCWorld area forecast centreWBWestboundWBARWing bar lightsWDIWind direction indicatorWDSPRWidespreadWEDWednesdayWEFWith effect from or effective fromWGS-84World Geodetic System - 1984WIWithinWIDWidthWIEWith immediate effect or effective immediatelyWILCO†Will complyWINTEMForecast upper wind and temperature for aviationWIPWork in progressWKNWeaken or weakeningWNWWest north westWOWithoutWPTWay-pointWRNGWarningWSWind shearWSWWest south westWTWeightWTSPTWaterspoutWXWeatherXCrossXBARCrossbar (of approach lighting system)XNGCrossingXSAtmosphericsYYellowYCZYellow caution zone (runway lighting)YRYourZCoordinated Universal Time (in meteorological messages)