AMDAR WVSSII

8/10/2019 AMDAR WVSSII

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WorldMeteorologicalOrganization

AMDAR

ONBOARD

SOFTWARE

FUNCTIONALREQUIREMENTS

SPECIFICATION

FrankTamis

3092012


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AOSFRSversion04 Page2of49

RevisionData

REVISIONSTATUS STATUSDATE DESCRIPTION

Draft January17,2012 Originalrelease,skeletondraft

F.C.Tamis,

AircraftDataEngineering&Consultancy

01 April18,2012 FirstConcept

F.C.Tamis,


02 May15,2012 SecondConcept

F.C.Tamis,


03 September29,2012 CompleteDraft

F.C.Tamis,


04 October27,2012 RevisionstocompletedraftbasedonWMOinput.

F.C.Tamis,

Airdatec


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TableofContents

1 INTRODUCTION................................................................................................................. 5

1.1 BACKGROUND....................................................................................................................... 5

1.2 OBJECTIVES .......................................................................................................................... 5

1.3 INTENDEDAUDIENCEANDSCOPE.............................................................................................. 5

1.4 CONVENTIONS ...................................................................................................................... 6

1.5 APPLICABLEDOCUMENTS........................................................................................................ 6

1.6 ABBREVIATIONSANDACRONYMS.............................................................................................. 7

2 AMDARSYSTEMOVERVIEW.............................................................................................. 8

2.1 AMDARSYSTEM .................................................................................................................. 82.2 AMDARONBOARDPROCESS.................................................................................................. 9

2.3 OTHERSPECIFICATIONS......................................................................................................... 10

2.4 FURTHERREADING.............................................................................................................. 11

3 AMDARONBOARDSOFTWAREREQUIREMENTS ............................................................. 12

3.1 DATAACQUISITION.............................................................................................................. 13

3.2 DATAHANDLING ................................................................................................................. 15

3.2.1 Dataacquisitionrate...............................................................................................................15

3.2.2 DataValidation........................................................................................................................16

3.2.3 DataSmoothing ......................................................................................................................16

3.2.4 DerivedParameters ................................................................................................................ 163.2.4.1 PhaseofFlight.................................................................................................................16

3.2.4.1.1 Ground ...................................................................................................................... 16

3.2.4.1.2 Ascent .......................................................................................................................17

3.2.4.1.3 EnRoute ...................................................................................................................17

3.2.4.1.4 Descent .....................................................................................................................17

3.2.4.2 TurbulenceIndicator .......................................................................................................17

3.2.4.3 WaterVapor/RelativeHumidity/DewPoint................................................................17

3.2.4.4 RollAngleFlag.................................................................................................................17

3.2.4.5 AircraftConfigurationIndicator......................................................................................19

3.3 AMDAROBSERVATIONS...................................................................................................... 19

3.4 OBSERVATIONFREQUENCY .................................................................................................... 203.4.1 EnrouteObservations ............................................................................................................20

3.4.1.1 MaximumWindObservation ..........................................................................................20

3.4.2 PressureBasedScheme .......................................................................................................... 21

3.4.2.1 RoutineObservations......................................................................................................21

3.4.2.2 Ascent..............................................................................................................................21

3.4.2.2.1 InitialObservation.....................................................................................................21

3.4.2.2.2 AmbientStaticPressureatTakeOff.........................................................................21


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1 Introduction

1.1 Background

TheGlobalAircraftMeteorologicalDataRelay(AMDAR)ProgramisaprograminitiatedbytheWorld

MeteorologicalOrganization(WMO)incooperationwithaviationpartners,andisusedtocollect

meteorologicaldataworldwidefromcommercialaircraft.TheWMOAMDARObservingSystemisasub

componentoftheWMOIntegratedGlobalObservingSystem,whichisdefinedandmaintainedunder

theWMOWorldWeatherWatchProgram1.

Existingaircraftonboardsensors,computersandcommunicationssystemsareutilizedtocollect,

process,formatandtransmitthemeteorologicaldatatogroundstationsviasatelliteorradiolinks.Once

ontheground,thedataisrelayedtoNationalMeteorologicalServices,whereitisprocessed,quality

controlledandtransmittedontheWMOGlobalTelecommunicationsSystem(GTS).

Thedatacollectedisusedforarangeofmeteorologicalapplications,including,publicweather

forecasting,climatemonitoringandprediction,earlywarningsystemsforweatherhazardsand,

importantly,weathermonitoringandpredictioninsupportoftheaviationindustry.

1.2 Objectives

ThisdocumentprovidesacomprehensivefunctionalspecificationforonboardAMDARsoftware.Itis

intendedthatthespecificationprovidessufficientinformationtoenabledetailedtechnicalspecifications

tobeprovidedforAMDAROnboardSoftwareimplementationonsuitableavionicsplatforms.

1.3 IntendedAudienceandScope

Thespecificationisprimarilyintendedforusebybothmeteorologicalagenciesandavionicssoftware

developerstoallowthemtojointlydevelopAMDARsoftwarewithminimaladditionalinformation.It

definestheFunctionalSpecificationsoftheAMDAROnboardSoftwareonly.FunctionalSpecificationsof

otherpartsoftheAMDARdataflow,suchasgroundbasedprocessing,areoutsideitsscope.

Thespecificationwillbeapplicableforallkindsofonboarddataprocessingandcommunicationssystem

solutions,includingACARSand/orsuccessors.

Bydefinition,anaircraftbasedmeteorologicalobservingsystemthatconformstothisspecification,and

mostparticularlytothoserequirementsthataredesignatedasrequired(seeconventions,paragraph

1.4),canbeconsideredanAMDARobservingsystem.

1TheWMOWorldWeatherWatchProgramme:http://www.wmo.int/pages/prog/www/index_en.html


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1.4 Conventions

Thekeywords"must","mustnot","required","shall","shallnot","should","shouldnot",

"recommended","may",and"optional"inthisdocumentaretobeinterpretedasfollows:

1.ThetermsSHALL,"REQUIRED"or"MUST"meanthatthedefinitionisanabsoluterequirementof

thespecification.

2.ThephrasesSHALLNOTor"MUSTNOT"meanthatthedefinitionisanabsoluteprohibitionofthe

specification.

3.ThetermsSHOULDor"RECOMMENDED"meanthatthere mayexistvalidreasonsinparticular

circumstancestoignoreaparticularitem,butthefullimplicationsmustbeunderstoodand carefully

weighedbeforechoosingadifferentcourse.

4.ThephrasesSHOULDNOT or"NOTRECOMMENDED"meanthattheremayexistvalidreasonsin

particularcircumstanceswhentheparticularbehaviorisacceptableorevenuseful,butthefull

implicationsshouldbeunderstoodandthecasecarefullyweighedbeforeimplementinganybehavior

describedwiththislabel.

5.ThetermsMAYor"OPTIONAL"meanthatanitemistrulyoptional. Onevendormaychooseto

includetheitembecauseaparticularmarketplacerequiresitorbecausethevendorfeelsthatit

enhancestheproductwhileanothervendormayomitthesameitem.Animplementationwhichdoes

notincludeaparticularoptionMUSTbepreparedtointeroperatewithanotherimplementationwhich

doesincludetheoption,thoughperhapswithreducedfunctionality.Inthesameveinanimplementation

whichdoesincludeaparticularoptionMUSTbepreparedtointeroperatewithanotherimplementation

whichdoesnotincludetheoption(except,ofcourse,forthefeaturetheoptionprovides.)

1.5 ApplicableDocuments

Whereappropriate,referencesareprovidedtoWMO,InternationalCivilAviationOrganization(ICAO),

AeronauticalRadioIncorporated(ARINC)orotherdocumentsthataresubjecttoissueandreviewbythe

respectiveorganizations.Norecommendationsorotherinformationinthisspecificationoverridesor

supersedestherequirementscontainedinreferenceddocuments,unlessspecifiedotherwise.


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1.6 AbbreviationsandAcronyms

ACARSAircraftCommunicationAddressingandReportingSystem

ACMSAircraftConditionMonitoringSystem

AMDAR

Aircraft

Meteorological

Data

Relay

ARINCAeronauticalRadio,Incorporated

ASDARAircrafttoSatelliteDataRelay

DASDataAcquisitionSystem

DEVGDerivedEquivalentVerticalGust

EDREddyDissipationRate

GNSSGlobal Navigation Satellite System

IATAInternationalAirTransportAssociation

ICAOInternationalCivilAviationOrganization

Q/CQualityControl

SATStaticAirTemperature

TATTotalAirTemperature

UTCUniversalTimeCoordinate

WMOWorldMeteorologicalOrganization

VHFVeryHighFrequency


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2 AMDARSystemOverview

2.1 AMDAR

system

TheAMDARsystemisdefinedbythecharacteristicthatitisameteorologicalobservingsystemthat

utilizesaircraftinnatesensorsandonboardavionicsandcommunicationssystemsinordertocollect

processandtransmitmeteorologicaldatathathasbeendefined,sampledandprocessedaccordingto

WMOmeteorologicalspecifications.

ThefullAMDARsystemcomprisestheendtoendsystemofprocessesandpractices,startingfrom

measurementbyaircraftsensorsrightthroughtothedeliveryofthedatatoDataUsers.Ontheaircraft,

AircraftDataComputersobtainprocessandformatdatafromonboardsensors,andtransmitdatato

groundviastandardaircraftcommunicationsystems.Onceontheground,thedataarerelayedtothe

NationalMeteorologicalServices(NMS)andotherauthorizedusersasshowninFigure1.Dataare

receivedatthedataprocessingcentersoftheNMSwheretheyaredecodedandundergobasicquality

controlchecksbeforebeingreformatted fordistributiontoDataUsersbothinternaltotheNMSand

externallytootherNMSsviatheWMOGlobalTelecommunicationSystem(GTS).

Figure1:AMDARDataFlow

Thisdocumentisconcernedonlywiththespecificationoffunctionalrequirementsfortheairborneor

onboardsoftwarecomponentoftheAMDARsystem,theAMDAROnboardSoftware.


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2.2 AMDAROnboardProcess

ThepurposeoftheairbornepartoftheAMDARProcess,henceforthreferredtoastheAOP,istocollect,

processandtransmitmeteorologicaldatafromsensorsonboardtheaircraft.Theprimaryfunctionsof

theAOPare:

Interfacetoandacceptinputdatafromavarietyofaircraftinnateavionicsequipment;

Performhighlevelqualitychecksontheinputdata;

Performcalculationsupontheinputdatatoderiverequiredmeteorologicalvariables;

Atsetintervals,processcollecteddataintostandardoutputmessagesfortransmissionto

groundstations;and,

Acceptandprocessinputs,allowinguserstoaltertheAOSbehavior.

To meet these primary functional requirements, AMDAR relies on the availability of onboard data

acquisitionsystemsthatarecapableofbeingprogrammedtoperformtherequiredfunctions.Therefore,

the firstandmost fundamental requirementof theAMDAROnboardSystem is that theaircraftmusthaveaDataAcquisition System (DAS) thatmustbeprogrammableand support interfacing toall the

requireddatainputsandtotheaircraftscommunicationssystem.

AnexampleofsuchanonboardsystemisillustratedinFigure2,whichshowsschematicallytheprincipal

datasourcesfeedingintoaDAS.Notethattheconfigurationsandavailabilityofsystemsvarieswidely

betweenaircraftmodelsandairlinefleets.

Data Aqcuisition

System

(programmable)

ACARS

Clock

1. Temperature

Wind Speed

Wind Direction

Altitude

2. Latitude

Longitude

3. Tail Number

Flight Number

4. Time (UTC)

5. Vertical Acceleration

6. AMDAR report

CENTRAL

MAINTENANCE

COMPUTER

1

3AIR DATA

COMPUTERS

6

2

INERTIAL

REFERENCE

UNITS

4 5

Flight Data

Recorder

Figure2:ExampleDataAcquisitionSystem

TypicalinputstotheDASare,forexample,PressureAltitudeorStaticAirPressure,WindSpeed/

Directionandothers.Theseinputparametersareprocessedbythesoftwareaccordingtopredefined


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samplingfrequenciesandtheresultingdatavariablesarestoredasameteorologicalobservation.

Then,dependingonthecommunicationssystemusedandrequirementsassociatedwithmessagecosts

andefficiency,datalatency,phaseofflightandotherparameters,whentherequirednumberof

observationshasbeenobtained,theyarewrittentoastandardizedmessagethatissubsequentlysentto

theground.

Theactualtriggeringoftheprogrammaticprocessesthatcreatetheseobservationsdependsonseveral

parametersthatareembeddedinthesoftware,manyofwhichareconfigurablethroughaninterfaceto

theAMDARsoftwareprogram.Theseparameterstellthesoftwarewhentoreportornottoreport.

Examplesofsuchparametersarephaseofflight,i.e.whethertheaircraftisascending,descendingorin

levelflight, pressurealtitude,geographicalpositionoftheaircraft,i.e.observationsaremadeonly

withinoroutsideofpredefinedgeographicallocations,andtimeofday,i.e.reportingisonlydonewithin

adefinedtimeframe.Bymakingtheseparametersconfigurable,theobservingandreportingregimefor

AMDARisabletobemodifiedaccordingtochangingmeteorological,programmaticoreconomic

requirements.

Additionally,bytakingadvantageoftwowayaircrafttogroundcommunicationsthatareoften

availablewithmodernaircraftavionicsandcommunicationssystems,itispossibletofacilitate

modificationoftheseprogramparametersviacommandsembeddedwithinuplink messages,whichare

usuallycompiledandsentbyautomated,groundbasedcontrolsystemsinnearrealtime.Thisprocessis

knownasAMDARdataoptimization.AMDARoptimizationsystemsallowNMSandairlinestomanage

datavolumesandeliminateredundantobservationsandmessagesthroughrealtimeAMDARsoftware

modificationeitherpriortoorduringaircraftflightandonaflightbyflightbasis.

TheendresultoftheAMDARonboardsystemistheproductionoftheAMDARmessagescontainingthe

meteorologicalobservations.Thesemessagesaretransmittedtothegroundbysuitabledatalink

communicationsystemsandrelayedbyaviationDataServiceProviderstotheNMS. Thecontentsofthe

messagesareprocessedandthedataareingestedintometeorologicaldatabasesandapplications.

2.3 OtherSpecifications

Therearemanypossibleformatspecificationsformeteorologicalmessagesfromaircraft. Inorderto

avoidtheproliferationofdataformatsandreducetheoverheadsandcomplexityforcomplianceby

groundprocessingsystems,thisdocumentprovidesafunctionalrequirementsspecificationthatwillbe

knownasAMDAROnboardSoftwareFunctionalRequirementsSpecification(AOSFRS)Version1.0.This

specificationisbasedontheASDARSpecification2,theEAMDARAAAVersion2.0Specification(AAA

V2)3andtheAMDARAAAVersion3.0specification(AAAV3)4. Allinformationinthisdocument

supersedesthepreviouslymentioneddocuments.Someinformationinthisdocumentisderivedfrom

2SoftwareRequirementsSpecificationfortheASDARProject,Issue3,MatraMarconiSpaceUKLimited,October

1994(reference116300016444).

3EUMETNETAMDARAAAAMDARSoftwareDevelopmentsTechnicalSpecification,Version2,1August2000.

4PROGRAMOPERATIONSANDSTANDARDSOBSERVATIONSSPECIFICATION20061,AMDARAAAVersion3.0

SoftwareRequirementsSpecification,23November2006


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ARINCspecification620(meteorologicalreportversion1thru5).TheARINCspecificationhoweverisnot

supersededbythisdocument.

Sincemostmeteorologicalmessagesshareacommonapproachtoprocessing,triggeringand

transmittingdataitispossibletousethisspecificationinconjunctionwithotherspecifications.In

particular,theARINC620MeteorologicalReportspecificationisarecognizedstandardforAMDARanditisthereforefeasibleandacceptabletospecifythatparticulardownlinkformatstandardasanalternative

tothosespecifiedwithinthisdocument.

Toallowtheusertochoosebetweenoptionalformats,thisspecificationshallrefertotheARINC620

(latestversion)specificationwhereappropriate.

2.4 FurtherReading

AdetaileddescriptionoftheAMDARsystemisgivenintheAircraftMeteorologicalDataRelay(AMDAR)

ReferenceManual(WMONo958)availablefromtheWorldMeteorologicalOrganization,Geneva,

Switzerland:

http://www.wmo.int/amdar/Publications/AMDAR_Reference_Manual_2003.pdf

andintheWMOGUIDETOMETEOROLOGICALINSTRUMENTSANDMETHODSOFOBSERVATION,Part2,

Chapter3,AircraftObservations:

http://www.wmo.int/pages/prog/www/IMOP/CIMOGuide.html
http://www.wmo.int/amdar/Publications/AMDAR_Reference_Manual_2003.pdfhttp://www.wmo.int/amdar/Publications/AMDAR_Reference_Manual_2003.pdfhttp://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.htmlhttp://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.htmlhttp://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.htmlhttp://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.htmlhttp://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.htmlhttp://www.wmo.int/amdar/Publications/AMDAR_Reference_Manual_2003.pdf


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3 AMDAROnboardSoftwareRequirementsAsdescribedinchapter2,theprimaryfunctionsoftheAMDAROnboardProcessare:

Acceptinputdatafromavarietyoftheaircraftinnateavionicsequipment.

Performhighlevelqualitychecksontheinputdata

Performcalculationsupontheinputdatatoderiverequiredmeteorologicalparameters

Atsetintervals,processcollecteddataintostandardoutputmessagesfortransmissionto

groundstationsand

Acceptinputs,allowinguserstoaltertheAMDAROnboardSoftwarebehavior.

Figure3showsahighlevelschematicoftheAMDARonboardprocess. Thischapteraimstotranslatethe

functionsinthisschematicintofunctionalrequirementsfortheAMDARonboardsoftware.


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Data Handling

AMDARMessage

Compiler

AMDAR MessageConfiguration

Message

SoftwareConfiguration

ConfigurationModule

ConfigurationMessage

Compiler

Observations

Observation

Scheduler

Aircraft Avionics Data In

AMDAR Inf ormation Out AMDAR Messages, AMDAR Configurati on

Message

Configuration

Setting

s(uplink/flightdeck/codechanges)

Data Aqcuisition

AMDAR ONBOARD SOFTWARE

Figure3:AMDAROnboardProcess

3.1 DataAcquisition

Thedataacquisitionsystemshallprovideadatainterfacetothehighestqualitydatasourcesavailable

fromtheaircraft.Incasethedirectsourceisnotavailabletotheacquisitionsystemitisacceptableto

useanindirectsource,aslongasthequalityofthedataismaintained(e.g.thelatitudecomesfromthe

inertialreferencesystembutthissourceisnotconnecteddirectly totheAOS.Latitudeishowever

transmittedtotheFMCandthissourceisavailabletotheAOS.Aslongasdataqualityismaintainedthe

latitudecanbeobtainedfromtheFMCinsteadofdirectlyfromtheIRS)

Thetablesbelowprovidetheinputsignalsthatneedtobeacquired.Distinctionismadebetweensignals

thatshallbeacquired(Table1

Table1:InputSignals Required

),shouldbeacquired(Table2)andsignalsthatareoptional(Table3).

DESCRIPTION UNIT RANGE ACQRATE

PREFERRED MAX


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AIRCRAFTID INT N/A N/A N/A

AIR/GROUNDSWITCHORWEIGHTONWHEELS DISCRETE N/A 1HZ 1HZ

COMPUTEDAIRSPEED KTS 0TO800KNOTS 1HZ 2HZ

DATEDAY DD 031 1HZ 4HZ

GMTHOURS HH 0023 1HZ 2HZ

GMTMINUTES MM 0059 1HZ 2HZ

GMTSECONDS SS 0059 1HZ 2HZ

LATITUDE DEGR 90STO90N 1HZ 4HZ

LONGITUDE DEGR 180ETO180W 1HZ 4HZ

PRESSUREALTITUDEINICAOSTANDARDATMOSPHERE1)

BAROMETRICALTITDUEINQNHADJUSTEDATMOSPHERE1)

FT1,000TO50,000

FEET1HZ 2HZ

STATICAIRTEMPERATURE DEGR.C 99CTO+99C 1HZ 2HZ

STATICPRESSURE2) HPA(=MB) 1HZ 1HZ

WINDDIRECTIONTRUE DEGR 0TO360 1HZ 2HZ

WINDSPEED KTS 0TO800KNOTS 1HZ 2HZ

Note1: PressureAltitudeinICAOStandardAtmosphere=PALT

BarometricAltitudeinQNHadjustedatmosphere=BALT

IfbothPALTandBALTareavailable,PALTshouldbeused.

Note2: Ifstaticpressureisnotavailablefromtheaircraftsystemsitcanbecalculatedfrompressurealtitude

ForPALTequaltoorlessthan36089ft.,staticpressure(SP)isrelatedtoPALT(ft)bythefollowingexpression:

SP(hPa)=1013.25[1106x6.8756(PALT)]

5.2559

IfPALTisgreaterthan36089ft,staticpressureisgivenby:SP(hPa)=226.32exp((PALT36089)/20805)


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Table2:InputSignals Recommended


PREFERRED MAX

DEPARTURESTATION CHAR N/A N/A N/A

DESTINATIONSTATION CHAR N/A N/A N/A

VERTICALSPEED3)

FT/MIN 2000TO2000 1HZ 1HZ

GROSSWEIGHT KG N/A 1HZ 16HZ

VERTICALACCELERATION G 3GTO+6G 8HZ 4HZ

ROLLANGLE DEGR 180TO180 1HZ 1HZ

PITCHANGLE DEGR 90TO90 1HZ 1HZ

Note3: Verticalspeedisusedinphaseofflightdetermination.Verticalspeedmaybederivedfromaltituderateofchange

Table

3:

Input

Signals

Optional


PREFERRED MAX

WATERVAPORDATA/RELATIVEHUMIDITY NOTE4 1HZ 4HZ

ICINGDATA DISCRETE N/A 1HZ 4HZ

FLAPS DEGR 1HZ 4HZ

GEARDOWN/UP DISCRETE N/A 1HZ 2HZ

GNSSALTITUDE FT 1,000TO50,000FEET 1HZ 1HZ

GROUNDSPEED KTS 0TO800KNOTS 1HZ 2HZ

TRUETRACK DEGR 1HZ 2HZ

TRUEHEADING DEGR 0TO360 1HZ 2HZTRUEAIRSPEED KTS 0TO800KNOTS 1HZ 2HZ

Note4: WaterVapor/Humidityismeasuredandreportedeitherasmixingratioorrelativehumidity,dependingonthetypeof

sensoremployed.Themassmixingratiovalueistobereportedasnnnnn=n1n2n3n4n5whichimpliesamassmixingratio

valueof(n1n2n3n4)x10(3n5)

kg/kg;e.g.,ifnnnnn=12345,thenthemassmixingrationisgivenby1234x10(3 5)

=1234x108

kg/kg.

RelativeHumidityisreportedasnnnnnwheretherangeofnnnnnisbetween00000and10000inhundredsofpercent.

3.2 DataHandling

3.2.1 Dataacquisitionrate

Input

data

can

be

acquired

at

different

acquisition

rates.

For

instance,

data

can

be

acquired

8

times

per

secondbutitisalsopossibletohaveparametersacquiredonceeverytwoorfourseconds.Following

rulesdescribehowtohandleacquisitionrates.

1. Forinputdataacquiredoncepersecond,nospecialruleapplies

2. Forinputdataacquiredmorethanoncepersecond,thelastvalidsamplewithinthatsecond

shallbeused


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3. Forinputdataacquiredlessthanoncepersecond,thelastvalidsampleshallbeused.

3.2.2 DataValidation

InputDatashouldonlybeusedwhen:

1. Itisvalidatedusingapplicableavionicsvalidationstandardsand,

2. ItpassestheoutofRangecheck.Inputdatavaluesshouldbecheckedagainsttherangegivenin

Table1,Table2andTable3.Whentheinputdatavaluefallsoutsidethisrangeitisconsidered

invalid.

Datathatisinvalidshallnotbeusedinanycalculation.Observationsshallcontinuebutinvaliddatashall

eithernotreported,orbemaskedasspecified,usuallywithasolidi(/).

3.2.3 DataSmoothing

WhilepreviousspecificationsfortheAOShaveincorporatedalgorithmsforsmoothingoraveragingdata

parameters,thispracticeisnotrecommendedwithoutclearscientificallybasedjustification.Smoothing

oraveragingshouldnotbeimplemented.

3.2.4 DerivedParameters

3.2.4.1PhaseofFlight

AMDARobservationintervalsshouldbelinkedtoaircraftflightphase.Thefollowingphasesofflight

conditionsshouldberecognized:

a) Ground

b) Ascent

c) Level

flight

(or

Cruise

or

En

route)

d) Descent

AnassessmentofthePhaseofFlightshouldbemadeatregularonesecondintervals.Theaircraftwillbe

consideredtooccupyoneofthephasesofflightatanytime,buttransitionfromonephasetoanother

doesnotnecessarilyfollowtheorderlistedabove,exceptthatPhaseAscentshallalwaysfollowPhase

or60se inimum.Groundf condsm

3.2.4.1.1 Ground

Theaircraftisconsideredonthegroundwhenitisnotinoneofthereportingflightmodes(ascent,en

routeordescent).Theaircraftisingroundphasewhen:

1. ComputedAirspeedisequaltoorlessthan100knotsorComputedAirspeeddataisinvalid,and

2. Air/groundswitchindicatesgroundorweightonwheelsistrue

Duringthisphasethesoftwareprocessesdatabutnoobservationnoraretransmissionsmade


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3.2.4.1.2 Ascent

Theaircraftisinascentwhen:

1. ComputedAirspeed>100ktsand

2. AltitudeRate>+200feet/minand

3. a.Pressurebasedscheme:PressureAltitudeTopofClimb(seeTable7)or

.Time eme:Flighttimesincetakeoff>Ascenttotalduration(seeb basedsch

3.2.4.1.4 Descent

)

Theaircraftisindescentwhen:

1. ComputedAirspeed>100ktsand

2. AltitudeRate


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Theflagisusedinoneoftwomodes:

Mode1:eitherasaqualityindicatorforwindspeedanddirectionbasedontheaircraftrollangle(RA)

andpitchangle(PA)(Mode1),or,

Mode2: toprovideanindicationofwhichrangebintheaircraftrollanglevaluelieswithin.

InMode1,theRollAngleFlagwilltakethevalueB,G,H,WorU,withthecorrespondingmeaning

providedinthetablebelow.

InMode2,theRollAngleFlagwilltakeeitherthevalueH,WorUwiththesamemeaningforMode1,or

anintegervaluefrom0to9.

ThevaluesWandUareusedwithinanEnrouteWeathermessageonlytoindicatethattheWindSpeed

constitutesaMaximumWindReportasperthecriteriadefinedinParagraph3.4.1.1.

Table4:RollAngleFlagvalues

ROLLANGLEFLAGVALUE MEANING MODE

B |RA| 5OR(|RA|3AND|PA| 3) 1

G |RA|


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3.2.4.5AircraftConfigurationIndicator

Aderivedparameterrepresentingtheaircraftconfigurationstatusmaybeaddedtothemeteorological

observationdata.Whenused,theparametershallbeassignedavalueaccordingtotheconfiguration

statusoftheaircraftasinthefollowingtable:

Table5:AircraftConfigurationIndicatorValues

VALUE MEANING

0 CONFIGURATIONUNDEFINED/NOTREPORTABLE

1 CLEANCONFIGURATION,GEARRETRACTED

2 FIRSTPOSITIONOFFLAPSEXTENSION,GEARRETRACTED

3 SECONDPOSITIONOFFLAPSEXTENSION,GEARRETRACTED

4 THIRDPOSITIONOFFLAPSEXTENSION,GEARRETRACTED

5TO7 RESERVED

8 ONLYLANDINGGEARDOWNANDINPLACE

9 FIRSTPOSITIONOFFLAPSEXTENSION+LANDINGGEARDOWNANDINPLACE

10 SECONDPOSITIONOFFLAPSEXTENSION+LANDINGGEARDOWNANDINPLACE

11 THIRDPOSITIONOFFLAPSEXTENSION+LANDINGGEARDOWNANDINPLACE

12TO14 RESERVED

15 WEIGHTONWHEELS=TRUE

3.3 AMDARObservations

AcrucialfunctionoftheAMDARsoftwareistotriggerandstoreobservations.Anobservationisasingle

setof(calculated)parametervaluesatapointinspaceandtime.

Observationsaremadeduringfollowingphasesofflightonly:

Ascent

Enroute(orCruise) Descent

Observationsshallbemadeeither:

1) Whenapresetstaticpressurelevelisreached(Pressurebasedscheme,default)

2) Whenapresettimeperiodhaselapsed(TimeBasedscheme)

Thesoftwareshallbecapableofswitchingbetweeneitherschemebutonlyoneschemeshallbeactive

atanygiventime.

Observationsshallbestoredinadedicatedareaofmemoryuntilrequired.


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3.4 ObservationFrequency

Thefrequenciesatwhichmeteorologicalobservationsaremadedependonthephaseofflightthe

aircraftisin.Eachobservationhasthesameorderingofmeteorologicalinformationbutthetriggering

frequencycanvarywithphase.

ThefigurebelowillustrateshowAMDARshoulddifferentiatebetweenthevariousflightphases.

Ascent

Part 1

Ascent

Part 2En-route

Descent

Part1

Descent

Part 2

Top of Climb

100hPa

Top of Descent

Figure4:AMDARflightphases

Thetablebelowdescribestheobservingfrequencyforthevariousflightphases.Paragraphsfollowing

providedetailedinformationontheobservingfrequency

Table6:AMDARobservingIntervalbyflightphase

Table6

PRESSUREBASEDSCHEME TIMEBASEDSCHEME

ASCENTPART1 5OR10HPAINTERVALSFORFIRST100HPA 3TO20SECSINTERVALS(DEFAULT6)FOR30TO200SECS

(DEFAULT90)

ASCENTPART2 25OR50HPAINTERVALSABOVEFIRST100HPA 20TO60SECSINTERVALS(DEFAULT20)FOR490TO

1050SECS(DEFAULT510)

EN

ROUTE: 1TO60MINUTEINTERVALS(DEFAULT7)

DESCENTPART1 25OR50HPAINTERVALSFROMTODTOLAST

100HPA

20TO300SECSINTERVALS(DEFAULT40)FROMTOPOF

DESCENTTOTOUCHDOWN.

DESCENTPART2 5OR10HPAINTERVALSFORLAST100HPA

Theparagraphsbelowprovidedetailedinformationonthecontentof .

3.4.1 En-routeObservations

TheEnrouteobservationfrequencyisgenerictoboththepressureandtimebasedscheme.

Observationsshallbetriggeredatsettimeintervalsonly. Enroutedatameasurementsshouldbeginat

theconclusionofAscentandterminatewhenDescentobservationmeasurementsbegin.

FortimeintervalvaluesseeTable8.

3.4.1.1MaximumWindObservation

Thisfacilityisrequiredtoaidinlocatingjetstreamcoresandisappliedinenrouteflightphaseonly.The

highestwindspeedmeasuredbetweenasequentialpairofroutineobservationsislabeledmaximum

wind.Maximumwindisderivedaccordingtothefollowingcriteria:


21/49


1. Observationsofwindspeedmaximawillonlybereportedwhentheambientpressureis lower

than600hPa,and

2. Theaircraftisinenroute,and

3. Thewindspeedexceeds60knotsabsolute,and

4. The wind speed exceeds by 10 knots or more the value observed at the previous routine

observation,and

5. Thewind speedexceedsby10 knots ormore the valueobservedat the subsequent routine

observation.

TheMaximumWindoption,providesanadditionalobservationthatistakenatthetimeofoccurrence

ofthepeakwindmeasurement,usingthemaximumwindindicator(seeTable4)

3.4.2 PressureBasedScheme

3.4.2.1RoutineObservations

Routineobservationwillensuredataisstillcollectedatregulartimeintervalsinthecasewherethe

aircraftlevelsoffduringascentand/ordescentandstaticpressuretriggeringcannotbeusedsincethe

staticpressuredoesnotchangeduringlevelflight.Itwillalsoensurethatobservationsaretakenifthe

aircraftdoesnotreachthesetaltitudefortopofclimb.

Routineobservationsshallbemadeatsettimeintervalsduringflightphaseascentanddescent. The

intervaltimerresetsandcommencesfollowingeachobservation.Ifnopressurelevelchangeis

encounteredduringthepresettimeinterval,anobservationistriggeredandthetimerisreset.Thetime

intervalisthesameastheenrouteobservationtimeinterval(seeparagraph3.4.1)

3.4.2.2

Ascent

DuringPhaseofFlightAscent,observationsshallbemadeatdefinedAmbientStaticPressurelevels

whichwillbeknownas"AscentTargetPressures".ThesewillbereferencedtotheAmbientPressureat

takeoff.

3.4.2.2.1 Initial Observation

Meteoro dalogical (takeoff).tameasuredatthetimeoftheOFFevent

3.4.2.2.2 Ambient Static Pressure at TakeOff

Atthetimeoftakeoff,theAmbientStaticPressureshallbedeterminedbynotingtheaveragevalueofp

takenbetweenthesecondsuccessivemeasurementoftheComputedAirspeedthatexceeds60knots

andthesecondsuccessivemeasurementoftheComputedAirspeedthatexceeds90knots.TheAmbient

StaticPressureattake offwillbestored.

IftheComputedAirspeedfallsbackbelow60knotsbeforeAscentisentered,butafteranAmbientStatic

Pressureattakeoffvalueisstored,thenthevaluestoredshallbeoverwrittenwhentheComputed

Airspeednextincreasesfrom60through90knots.


22/49


3.4.2.2.3 Ascent Part 1

ObservationsshallbemadewhentheAmbientStaticPressurefirstfallsbelowtheAscentTarget

Pressure.ThefirstAscentTargetPressureshallbethenearestmultipleof10hPa(modifiableto5hPa)

belowtheAmbientStaticPressureattakeoff.Thenextnine(modifiableto19if5hPaisused)Ascent

TargetPressuresshallfollowat10hPa(modifiableto5hPa)intervalsdecrementingfromthefirstAscent

essureTargetPr level.

3.4.2.2.4 Ascent Part 2

TheeleventhAscentTargetPressureshallbethenearestmultipleof50hPa(modifiableto25hPa)below

thetenthAscentTargetPressure.ThetwelfthandsubsequentAscentTargetPressuresshallfollowat50

hPa(modifiableto25hPa)intervalsdecrementingfromtheeleventhAscentTargetPressure.

Observationswillcontinueat50hPa(modifiableto25hPa)intervalsthroughouttheremainderofthe

AscentPhase.

ThecompleteAscentdataprofilewillthusconsistoftenobservationsat10hPa(ortwentyat5hPa)

intervalsoverthefirst100hPa,andObservationsat50hPa(or25hPa)intervalsthereafteruntilthe

Ascentiscomplete.

3.4.2.3Descent

DuringPhaseofFlightDescent,ObservationsshallbemadeatdefinedAmbientStaticPressurelevels,

whichwillbeknownas"DescentTargetPressures".

ThefirstDescentTargetPressureshallbethefirstmultipleof50hPa(modifiableto25hPa)abovethe

pressurerecordedwhentheDescentphasewasestablished.SubsequentDescentTargetPressuresshall

beat50hPa(modifiableto25hPa)intervals.ObservationsshallbemadewhentheAmbientStatic

PressurefirstrisesabovetheDescentTargetPressure.

Atandabove700hPathesoftwareshall,inadditiontothecontinuedformationofObservationsat50

hPaintervals,formObservationsat10hPaintervalsincrementingfrom700hPa.Onlythetenmost

recentObservationsat10hPaintervalsareretained.Thisadditionalsamplingshallcontinueuntilthe

Descentiscompleted.Intheeventoftheaircraftlandingbeforeacompletesetof50hPa(modifiableto

25hPa)observationshavebeenmadethemessagewillbepaddedoutwiththe/characterfollowedby

anewmessagewhichcontainsthetenObservationsmadebeforetouchdown.Thecompletesetof

DescentObservationsisthusaseriesofobservationsat50hPaintervals,augmentedbyadetailed

verticalsurveyofthelast100hPain10hPaincrements,whichshallnotincluderepeatsofobservations

at50hPaintervals.


23/49


3.4.3 TimeBasedScheme

3.4.3.1A

3

scent

.4.3.1.1 Initial ObservationAninitial ationis

3.4.3.1.2 Part 1

observ triggeredattheOFFevent.

FollowingtheInitialobservation,observationsareaccumulatedatsettimeintervalsuntilthepart#1

limitis d,countedfromtheOFFevent.Forintervalanddurationvaluesseeduration reache

3.4.3.1.3 Part 2

Table7

Table7

ObservationsareaccumulatedfromtheexpirationofthePart#1dataacquisitionperiod.Part#2data

observationsaretakenatsettimeintervalsuntiltheAscenttotaldurationlimitisreached,countedfrom

theOFFevent.Forintervalanddurationvaluessee

3.4.3.2Descent

DescentdatameasurementsbeginatTopofDescentandareaccumulatedatasettimeinterval.Topof

Descentismodifiable.

ForTopofDescentandintervalvaluesseeTable9.

3.5 MessageCompilation

3.5.1 Content

Observationsarecollectedandstoredduringflight.Whenapresetnumberofobservationsarestored,

amessageshallbeformedcontainingtheseobservations.Afteramessageistransmitted,the

observationsshallbediscarded.Themessageshallhaveatleastthefollowinginformation:

IdentificationasAMDARdata

Softwareversionindicatori.e.whatspecificationitconformsto

Reportingscheme(timebasedorpressurebased)

Observationdata


24/49


3.5.2 Format

Themessageformatdependsonthestandardadopted.ForAOSFRS(thisdocument)seeAppendixA.

3.5.3 Transmission

Regardlessoftheformat,messagesshallbesendtothegroundassoonastheyarecompleteviathe

bestmeanspossible.

Pendingmessagesshallbesendeventhoughthepresetnumberofobservationshasnotbeenreached

insituationsoutlinedbelow:

1. Flightphasetransitions

Forexample;theaircrafttransitionsfromflightphaseascenttoflightphaseenroute,thepre

setnumberofobservationsistenbutonlyfiveobservationsarestored.Inthiscase,amessage

shallbesendwithonlyfiveobservations.

2. Reportingturnedoffbysoftwarecontrol

Forexample;reportingduringdescentisturnedoninitially.Duringdescent,reportingis

switchedoffbyuplinkcommand.Atthattimeonlysevenobservationswerestored.Inthiscase,

amessageshallbesendwithonlysevenobservations.Moreinformationonsoftware

configurationcontrolcanbefoundinparagraph3.6.


25/49


3.6 SoftwareConfigurationControl

Itshallbepossibletoconfigurethesoftwaretoallowreportingbehaviortobealtered.

Changesinconfigurationareestablishedbyanycombinationofthefollowingmethods(inorderof

preference):

1. ACARSuplinkcommands

2. Manualentrythroughflightdeckinterfacedisplays

3. Codechanges

Changestotheconfigurationbyoneofthemethodsdescribedaboveareconsideredpermanentuntil

changedagain.Ifforwhateverreasontheconfigurationsettingsarelost,thesettingsshallrevertto

default.

3.6.1 ObservationFrequency

Control

FollowingtablesdescribetherequiredobservationfrequencycontrolparametersforAscent,Enroute

andDescent.

Table7:Ascentobservationcontrolparameters

CHARACTERS DATA DESCRIPTION REMARKS

1 0OR1 PRESSUREBASEDSCHEME(0)ORTIMEBASEDSCHEME

(1)

DEFAULT =0

2 SS ASCENTPART1TIMEINTERVAL(SECONDS) TIMEBASEDSCHEME

DEFAULT=06

RANGE=0320

3 SSS ASCENTPART1DURATION(SECONDS) TIMEBASEDSCHEMEDEFAULT=090

RANGE=030200

2 SS ASCENTPART2TIMEINTERVAL(SECONDS) TIMEBASEDSCHEME

DEFAULT=20

RANGE=2060

3 SSS ASCENTTOTALDURATION(SECONDSX10) TIMEBASEDSCHEME

DEFAULT =051

RANGE=051111

2 NN PART1PRESSUREINTERVAL(HPA) PRESSUREBASEDSCHEME

VALUE=5OR10

DEFAULT=10

2 NN NUMBEROFOBSERVATIONSMADEDURINGASCENTPART1.

PRESSUREBASEDSCHEMEVALUE=10OR20

DEFAULT=10

NOTE:PART1PRESSUREINTERVALXPART

1NUMBEROFOBSERVATIONSMUSTBE100

2 NN PART2PRESSUREINTERVAL(HPA) PRESSUREBASEDSCHEME

VALUE=25OR50

DEFAULT=50

3 NNN TOPOFCLIMB(X100FT) DEFAULT=200


26/49


RANGE=1503501)

1 0OR1 ROUTINEOBSERVATIONSENABLED(1)ORDISABLED(0) DEFAULT=1

Note1:DefaultsettingsfortheTopOfClimbmustbechosentomatchoperationalprofilesoftheaircrafttype,i.e.

theymustbesetlowerthanthecommoncruisealtitudefortheaircrafttypethesoftwarewillbeinstalledon.

Table8:

En

route

observation

control

parameters


2 MM OBSERVATIONINTERVAL(MINUTES) DEFAULT=7

RANGE=160

1 0OR1 ENABLE(1)ORDISABLE(0)MAXIMUMWIND

REPORTING

DEFAULT=1

Table9:Descentobservationcontrolparameters


1 0OR1 PRESSUREBASEDSCHEME(0)ORTIMEBASEDSCHEME

(1)

0=DEFAULT

3 SSS DESCENTTIMEINTERVAL(SECONDS) TIMEBASEDSCHEMEDEFAULT=040

RANGE=010300

2 NN DESCENTPRESSUREINTERVAL(HPA) PRESSUREBASEDSCHEME

VALUE=25OR50

DEFAULT=50

3 NNN TOPOFDESCENT(X100FT) DEFAULT=200

RANGE=150350

1 0OR1 ROUTINEOBSERVATIONSENABLED(1)ORDISABLED(0) DEFAULT=1

3.6.2 ReportingControl

3.6.2.1

Reporting

on/off

Itshallbepossibletoturnreportingonoroffcompletelyorbyflightphase,inaccordancewiththetable

below:

Table10:AMDARswitch


1 N REPORTACTIVATIONFLAG 0=REPORTINGOFF(DEFAULT)

1=DESCENTPHASEONLYACTIVE

2=ENROUTEPHASEONLYACTIVE

3=ENROUTE&DESCENTPHASESACTIVE

4=ASCENTPHASEONLYACTIVE

5=ASCENT&DESCENTPHASESACTIVE

6=ASCENT&ENROUTEPHASESACTIVE

7=ALLFLIGHTPHASESON


27/49


3.6.2.2GeographicalControlboxes

Itshallbepossibletoconfigureaminimumof10geographicalboxesinwhichreportingisenabledor

disabled.Outsidetheseboxesreportingisdisableddependingontheairportlimitation(see

paragraph0).

Aboxisdefinedbysettingtwolateralandtwolongitudinalboundariesindegrees.Whendefiningthe

boundaries,SOUTHandWESTarenegativei.e.20Sis20and40Wis040

TheareawillalwaysbedefinedasthatbetweenLAT1toLAT2inasoutherlydirection,andLON1to

LON2inaneasterlydirection(20N80S,120W50Eforexample).

Figure5:GEOboxdescription

Theorderofpriorityfortheseboxesshouldbefrom10(ormoreifimplemented)to1,thusallowinga

largeareatobeenabledforreportingusingbox1andasmallerregiontobedisabledwithinthisbox,

usingbox2forexample. Defaultsettingsareasfollows:

Table11:Geographicalcontrolboxdefaultsettings

BOX LAT1 LAT2 LON1 LON2 STATUS

1 90 90 180 180 DISABLEREPORTING








9 90 90 180 180 DISABLEREPORTING10 90 90 180 180 ENABLEREPORTING


28/49


3.6.2.3Airportspecificreporting

Itshallbepossibletoconfigureaminimumof20airportsaroundwhichreportingforascent,descentor

both,canbeenabledordisabled.Thesettingsappliedtothesespecificlocationsshalltakepriorityover

thegeographicallimitingfunction.

EachairportshallbedescribedbyitsfourletterICAOairportdesignator.Aflagisusedtocontrol

whetherobservingduringascent,descentorbothisactivatedordeactivatedforthislocation.Following

tableshowstheparameterconfigurationforthefirstairport.Thisistoberepeated19times.

Table12:Airportcontrolparameters


4 IAIAIAIA ICAOAIRPORTDESIGNATOR 0000 =DEFAULT

1 FA AIRPORTACTIVATIONFLAG 0=ASCENTON/DESCENTON(DEFAULT)

1=ASCENTON/DESCENTOFF

2=ASCENTOFF/DESCENTON3=ASCENTOFF/DESCENTOFF

3.6.2.4TimeLimiting

Itshallbepossibletoconfigureasingletimewindowduringwhichreportingisinhibited.

Table13:Timelimitcontrolparameters


4 H1H1H2H2 DISABLEOBSERVATIONSBETWEENSELECTED

HOURS(0023)UTC,EVERYDAY

H1H1=STARTOFINHIBITPERIOD

H2H2=ENDOFINHIBITPERIOD

DEFAULT=0000Thedefaultvalueisinterpretedasnointervalselectedandreportthoughall24hourperiods.Theinhibit

periodstartsatthefirstdesignatedhourinthedayandendswhenthenextdesignatedhourisreached

thesameornextday.Thus2301meansinhibitbetween2300hoursand0100hoursthenextday,every

day.(twohoursspanningmidnightUTC).

3.6.3 ConfigurationMessage

Thesoftwareshallprovideforamessagethatliststhecurrentsettingsforallofthecontrolparameters

mentionedinpreviousparagraph.

Themessagecanberequestedviaeither(inorderofpreference)

1. Anuplinkcommand.

2. Manualrequestthroughflightdeckinterfacedisplays

ForcontentsandformatoftheconfigurationmessageseeAppendixB


29/49


3.6.4 AMDAROptimizationMessage

AnAMDARoptimizationmessagemaybesenttotheNMSand/orairlinepriortodepartureofevery

flight.ThismessageallowstheNMSand/orairlinetoalterthesoftwareconfigurationpriortoflightand

therebymanagedatavolumesandeliminateredundantobservationsandmessages.

Forexample,anascentprofileisrequiredforanairportonlyonceperhour.Butifduringthathourmore

thenoneAMDARequippedaircrafttakesoff,thesystemisfilledwithdatathatisnotrequired.Inorder

topreventmultipleaircraftsendingAMDARmessages,agroundbasedsystemdetermineswhataircraft

toswitchoffbyusingtheinformationintheoptimizationmessage.

TheoptimizationmessagemaybeastandardOOOImessagebutshouldatleastcontain:

AircraftIndicator

TimeOut(leavinggateorparkingposition)

Departure/ArrivalStation


30/49

AppendixA AOSFRSmessageformatversion04

A.1 Introduction

ThisappendixspecifiestheAOSFRSmessageformat.TheAOSFRSmessageformatprovidesabasicmeteorologicalmessagewithonlytheminimumamountofinformationthatwillstillrenderamessage

usefulasameteorologicalmessage.Atthesametimeitallowsmaximumflexibilitytoaddinformation

thatenhancesthebasicreport,ifthisinformationisavailable.

Reasonforthisapproachistoallowtheformattobeusedonawidevarietyofaircraft/airlineswhere

somemayonlyhavethebasicinformationavailable,andothersmaybeabletoprovidealotmore

information.

Thedatathatissendtothegroundissetupintwosections,thefirstaheadersectionwithinformation

suchastheAOSFRSmessageversionandtheaircraftidentifier,thesecondpartconsistsof10

observationswiththerelevantparametervalues.Adetaileddescriptionisgivenbelow.

A.2 Header

Eachmessageshallhaveaheadercontainingtheinformationasdescribedinthetablebelow.

Table14:AOSFRSmessageheader

LINE

NUMBER

CHARACTER

NUMBER

#OFCHAR CONTENT FORMAT NOTES

1 13 3 AMDARMESSAGEVERSION A04

2 126 1TO26 OPTIONALPARAMETERINDICATION #ORATHRUZ SEEOPTIONAL

PARAMETERS

3 17 8 AMDARAIRCRAFTIDENTIFIER AAAAAAAA 1

3 8 1 NORMAL(N)ORCOMPRESSED(C) NORC 2

3 9 1 TIMEBASED(0)ORPRESSUREBASEDSCHEME

(1)

0OR1

3 10 1 ALTITUDEREFERENCE:PRESSUREALTITUDE

(P)ORBAROMETRICALTITUDE(B)

PORB 3

3 1114 4 DEPARTUREAIRPORT AAAA 4

3 1518 4 ARRIVALAIRPORT AAAA 4

Notes:

1. TheAMDARidentifierisassignedbytherequestingmetoffice.

2.

Normal means the data is not compressed. Compressed means the data is encoded using the

compressionschemedescribedinAppendixD.

3. PressureAltitudeinICAOStandardAtmosphere=PALT;

BarometricAltitudeinQNHadjustedatmosphere=BALT;

IfBALTisreported,conversiontothePressureAltitude(PALT)scalewillbenecessaryingroundprocessing

usingrunwayorareaQNHatthetimeoftheobservation.Thisisessentialbeforedatacanbeusedor

exchanged.IfbothPALTandBALTareavailable,PALTispreferred.


31/49


4. DepartureandArrivalairportarerepresentedbytheirICAOcode.Reportingofthesefieldsisoptionalbut

ifavailable,stronglyrecommended.

A.3 Body

Theheadershallbefollowedby10meteorologicalobservations,eachobservationononeline.The

observationsshallcontaintheBasicObservationSequenceasdescribedin .Allparametersshallberightjustified.

Table15

Table15:AOSFRSBasicObservationSequenceformat

A.3.1 BasicObservationsequence

CHARACTER

NUMBER

#OF

CHAR

CONTENT FORMAT NOTES EXAMPLE

1 1 PHASEOFFLIGHTINDICATOR A 1 R

26 5 LATITUDEINMINUTES SNNNN SOUTHISNEGATIVE 2976

712 6 LONGITUDEINMINUTES SNNNNN WESTISNEGATIVE 6081

1319 7 DAY/TIME NNNNNNN 2 8796612023 4 ALTITUDEINTENSOFFEET NNNN 3899

2427 4 STATICAIRTEMPERATURETENTHSOFC SNNN 525

2830 3 WINDDIRECTION NNN 160

3133 3 WINDSPEED NNN 025

Notes:

1. PhaseofFlightisindicatedasfollows:

Ascent =A

Enroute=R

Descent=D

2. The

day/time

is

presented

as

seconds

into

the

month,

and

is

calculated

as

follows:

( ( DATEDD- 1) *86400) + ( GMTHH*3600) + ( GMTMM*60) + GMTSS

Example1:

AnobservationismadeonJuly1stat20:53:22UTC,thecorrespondingday/timewillbe

((11)*86400)+(20*3600)+(53*60)+22=75202secondsintothemonth

Example2:

AnobservationismadeonNovember11that04:21:01UTC,thecorrespondingday/timewillbe((11

1)*86400)+(4*3600)+(21*60)+1=879661secondsintothemonth

A.3.2 OptionalParameters

TheBasicObservationSequencemaybeamendedwithoptionalparameters,iftheyareavailable.

OptionalparametersareassignedaHeaderIndicator(A,B,Cetc.)Thisletterisusedintheheaderto

indicatethatthebasicobservationsequenceisfollowedbyoneormoreoptionalparameter.Foreach

optionalparameterthatisaddedtothebasicobservationsequence,theHeaderIndicatorassociated

withtheoptionalparametershallbeaddedinline2intheheader.Thesequenceoftheletters

determinestheorderinwhichtheoptionalparametersareadded.A#inline2indicatesnoadditional

parametersfollowthebasicobservationsequence.


32/49


OptionalparametersaredescribedinTable16

Table16:AOSFRSOptionalParametersFormat

below.Allparametersshallberightjustified.

HEADERINDICATOR

#OFCHAR

CONTENT

FORMAT

NOTES

EXAMPLE

A 1 ROLLANGLEFLAG N SEEPARAGRAPH3.2.4.4 U

B 1OR9 EDR C

ORCNNNNNNNN

E12345678

C 3 DEVG NNN 7

D 3 TRUEAIRSPEED NNN 854

E 3 TRUEHEADING NNN 145

F GNSSALTITUDE NNNN 3750

G 1 ANTIICE(ENGINEORWINGORBOTH?) N 1 1

H 2 A/CCONFIGURATIONINDICATOR NN SEEPARAGRAPH0 01

I 6 WATERVAPOR NNNNNQ SEEAPPENDIXC.2ORCIMO? 123450

J

6

RELATIVE

HUMIDITY

NNNNNQ

SEE

APPENDIX

C.2

OR

CIMO?

05000U

K 1 ICING N 2 1

Notes

1.Antiice

Antiiceshallbereportedusingthefollowinglogic:

1 = Antiicenotactivated

2 = Antiiceactive

/ = Antiiceundeterminedorinvalid:

2.Icing

Icingwillbereportedasvalue1whentheaircrafticingsensorindicatesnoiceaccretion,asvalue2when

thesensorindicatesiceaccretionisoccurring,andasvalue0whenthestatusoficingisnotabletobe

determined(noterequiresseparatesysteminstalled,movenotetotable3inCH3)

Example1

Amessagewithonlythebasicobservationsequencewouldlookasfollows:

A4#AZ0001N1PEHAMKJ FKR- 2976 6081 8796613899- 525160 25R- 2976 6081 8796613899- 525160 25R- 2976 6081 8796613899- 525160 25

R- 2976 6081 8796613899- 525160 25R- 2976 6081 8796613899- 525160 25R- 2976 6081 8796613899- 525160 25R- 2976 6081 8796613899- 525160 25D- 2976 6081 8796613899- 525160 25D- 2976 6081 8796613899- 525160 25D- 2976 6081 8796613899- 525160 25


33/49


Thisindicatesthattheobservationsinthemessagearebasicobservationsonly,aircraftAZ0001isflying

fromAmsterdamtoNewYork,thedataisnotcompressedandtheobservationsinascentanddescent

arebasedonthepressurescheme,usingBarometricaltitude.


34/49


Example2:

GNSSandAntiiceareavailableandareaddedtothebasicobservationsequence.Amessagewould

thenlookasfollows

A04FGAZ0001N1BEHAMKJ FKA- 2976 6081 8796613899- 525160 25U38540A- 2976 6081 8796613899- 525160 2538540A- 2976 6081 8796613899- 525160 2538540A- 2976 6081 8796613899- 525160 2538540A- 2976 6081 8796613899- 525160 2538540A- 2976 6081 8796613899- 525160 2538540A- 2976 6081 8796613899- 525160 2538540

A- 2976 6081 8796613899- 525160 2538540A- 2976 6081 8796613899- 525160 2538540R- 2976 6081 8796613899- 525160 2538540

ThisindicatesthattheobservationsinthemessagearebasicobservationsamendedwithGNSSandAnti

iceinformation,aircraftAZ0001isflyingfromAmsterdamtoNewYork,thedataisnotcompressedand

theobservationsinascentanddescentarebasedonthepressurescheme,usingBarometricaltitude.

Example3:

WaterVapor,TrueAirspeed,Antiice,A/CconfigandEDRareavailableandaddedtothebasic

observationsequence,inthatorder.Themessagewouldlooklike:

A04I DGHBNL0032N0BWMKKYMMLA- 2976 6081 8796613899- 525160 25123450854101E12345678A- 2976 6081 8796613899- 525160 25123450854101E12345678R- 2976 6081 8796613899- 525160 25123450854101E12345678R- 2976 6081 8796613899- 525160 25123450854101E12345678R- 2976 6081 8796613899- 525160 25123450854101E12345678R- 2976 6081 8796613899- 525160 25123450854101E12345678R- 2976 6081 8796613899- 525160 25123450854101E12345678R- 2976 6081 8796613899- 525160 25123450854101E12345678D- 2976 6081 8796613899- 525160 25123450854101E12345678D- 2976 6081 8796613899- 525160 25123450854101E12345678

ThisindicatesthattheobservationsinthemessagearebasicobservationsamendedwithWaterVapor,

TrueAirspeed,Antiice,A/CconfigurationandEDRinformation,aircraftNL0032isflyingfromKuala

Lumpur toMelbourne,thedataisnotcompressedandtheobservationsinascentanddescentare

basedonthetimebasedscheme,usingBarometricaltitude


35/49


AppendixB AOSFRSConfigurationMessageAconfigurationmessagecanberequestedtoallowausertocheckthecurrentstatusofthe

configurationparametersusedbytheAOS.Theconfigurationmessageisonlyrequiredwhenitcanactuallyberetrievedfromtheaircraftsomehow.Adetaileddescriptionisgivenbelow.

SA4

I AI A DDDDAAAA Sp AsI phAaG:IsgA:IsaT:Ist

AI ntA1/N/I nt

A2RI nt

RDI nt

D1/ I nt

D2

TOCTL1

TODTL2

H1H2H3H4

BBN

LatY1/Lat

Y2Long

X1/Long

X2S

BBB

NLat

Y1/Lat

Y2Long

X1/Long

X2S

B

BBN

LatY1/Lat

Y2Long

X1/Long

X2S

BBB

NLat

Y1/Lat

Y2Long

X1/Long

X2S

B

BBN

LatY1/Lat

Y2Long

X1/Long

X2S

BBB

NLat

Y1/Lat

Y2Long

X1/Long

X2S

B

BBN

LatY1/Lat

Y2Long

X1/Long

X2S

BBB

NLat

Y1/Lat

Y2Long

X1/Long

X2S

B

BBN

LatY1/Lat

Y2Long

X1/Long

X2S BB

NLat

Y1/Lat

Y2Long

X1/Long

X2S

B

B

A1I CAON/S

AA5I CAO

N/S

AA9I CAO

N/S

AA13I CAO

N/S

AA17I CAO

N/S

A

A2I CAON/S

AA6I CAO

N/S

A10I CAO

N/S

A14I CAO

N/S

A18I CAO

N/S

A A A A

A3 I CAON/S

AA7 I CAO

N/S

AA11I CAO

N/S

AA15I CAO

N/S

AA19I CAO

N/S

A

A4 I CAON/S

AA8 I CAO

N/S

AA12I CAO

N/S

AA16I CAO

N/S

AA20I CAO

N/S

A

TheBoldand/charactersarefixedcharacters.

Table

17:

AOSFRSconfigurationmessage

contents

PARAMETER DESCRIPTION FORMAT NOTES EXAMPLE

SA04 STATUSFORAOSFRSMESSAGEVERSION AAAA SA04

I AI A AMDARIDENTIFIER(MAX8CHARACTERS) AAAAAAAA AU0013

DDDD DEPARTUREAIRPORT AAAA ICAOCODE EHAM

AAAA ARRIVALAIRPORT AAAA ICAOCODE KJFK

SP PRESSUREBASED(P)ORTIMEBASED(T)SCHEME A P

AS AMDARSWITCHSETTING N 7

IPH FLIGHTPHASEATTIMEOFREQUEST A 1 A

AA AMDARACTIVEATTIMEOFREQUEST(Y/N) A 2 Y

ISG GEOGRAPHICALINRANGEATTIMEOFREQUESTY/N A N

ISA AIRPORTACTIVEATTIMEOFREQUESTY/N A Y

IST TIMEWINDOWACTIVEATTIMEOFREQUEST A Y

INTA1 OBSERVINGINTERVALDURINGASCENTPART1,INHPAORSECONDS NN 10

N NUMBEROFOBSERVATIONSMADEDURINGASCENTPART1 NN 10

INTA2 OBSERVINGINTERVALDURINGASCENTPART2,INHPAORSECONDS NN 50

INTR OBSERVINGINTERVALDURINGLEVELFLIGHTINSECONDS NNN 420

INTD1 OBSERVINGINTERVALDURINGDESCENTPART1,INHPAORSECONDS NN 50

INTD2 OBSERVINGINTERVALDURINGDESCENTPART2,INHPA NN 10

TL1 TOPOFCLIMBSETTINGINTHOUSANDSOFFEET NNNN 2000


36/49


TL2 TOPOFDESCENTSETTINGINTHOUSANDSOFFEET NNNN 2000

H1H2H3H4 TIMEWINDOWSETTING NNNN 0000

BN GEOGRAPHICALBOXNUMBER(0TO9) N 1

LATY1 LATITUDEVALUEY1APPLIEDTOBOXBNINDEGREES SNN 30

LATY2 LATITUDEVALUEY2APPLIEDTOBOXBNINDEGREES SNN 50

LONGX1 LONGITUDEVALUEX1APPLIEDTOBOXBNINDEGREES SNNN 40

LONGX2 LONGITUDEVALUEX2APPLIEDTOBOXBNINDEGREES SNNN 120

SB STATUSOFBOXBN(1=REPORTINGACTIVE, 0=REPORTING

DISABLED)

N 1

ICAON ICAOCODEOFAIRPORTNUMBERAN AAAA EHAM

SA STATUSOFAIRPORT(1=REPORTINGACTIVE,0=REPORTING

DISABLED)

N 1

Notes:

1. Flightphasecharacters

G = Ground

A = Ascent

R = Enroute

D = Descent

2. AMDARactiveshowsifAMDARisreporting,asfollows

Y = AMDARisreporting

N = AMDARisinactive

MessageExample

SA04AU0113 EHAMKJ FK P 7 A Y G:0A:1 T:1

A10/ 10/ 50R420 D50/ 10TOC 20TOD20 0000B060/ 20 - 100/ 601 B5 0/ 0 0/ 0 0B1 0/ 0 0/ 0 0B6 0/ 0 0/ 0 0B2 0/ 0 0/ 0 0B7 0/ 0 0/ 0 0B3 0/ 0 0/ 0 0B8 0/ 0 0/ 0 0B B9 0/ 0 0/ 0 04 0/ 0 0/ 0 0

A1 EHAM/ 1A5 0000/ 0A9 0000/ 0A130000/ 0A170000/ 0A2KJ FK/ 0A6 0000/ 0A100000/ 0A140000/ 0A180000/ 0A A A A A3 0000/ 0 7 0000/ 0 110000/ 0 150000/ 0 190000/ 0A4 0000/ 0A8 0000/ 0A120000/ 0A160000/ 0A200000/ 0


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AppendixC OptionalDerivedParametersThisappendixdescribesthederivationforparametersthatarenotpartofthebasicobservation

sequence.

C.1 Turbulence

C.1.1 DerivedEquivalentVerticalGust

TheDerivedEquivalentVerticalGustVelocity(DEVG)isaturbulenceindicatordefinedasthe

instantaneousverticalgustvelocitywhich,superimposedonasteadyhorizontalwind,wouldproduce

themeasuredaccelerationoftheaircraft.Theeffectofagustonanaircraftdependsonthemassand

othercharacteristics,butthesecanbetakenintoaccountsothatagustvelocitycanbecalculatedwhich

isindependentoftheaircraft.

TheinformationbelowisanextractfromtheAustralianDepartmentofDefence,StructuresReport418,

TheAustralianImplementationofAMDAR/ACARSandtheuseofDerivedEquivalentGustVelocityasa

TurbulenceIndicator,DouglasJ.Sherman,1985.

Thevelocityofthederivedequivalentverticalgust,U ,(intenthsofmeterspersecond)maybe

calculatedbytheformula:

de

V

nAmDEVG

=10

wheren = peakmodulusvalueofdeviationofaircraftnormalaccelerationfrom1ginunitsofg.

m= totalaircraftmassin(metric)tonnes

V= calibratedairspeedatthetimeofoccurrenceoftheaccelerationpeak,inknots.

A= Anaircraftspecificparameterwhichvarieswithflightconditions,andmaybeapproximatedbythe

following

formulae:

A A c A cm

m= +

4 5 1( )


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A cc

c H kft = +

+12

3 ( )

=ValueofAwhenmassofaircraftequalsreferencemass

H= altitudeinthousandsoffeet

m= Referencemassofaircraftin(metric)tonnes

Theparameters dependontheaircraft'stypicalflightprofile.Forvariousaircraft,the

appropriateconstants,basedontheflightprofilesindicated,areshownin

c c c1 2 5, , ,K

Table18.


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Table18:DEVGaircraftconstants

Aircraft V1 Vc Mc h1 hc m c1 c2 c3 c4 c5

knot knot Mach ft ft Tonne kft

A300B4 130 300 0.78 5000 30000 120 0.971 2690 79 0.49 19.6

A310 130 300 0.78 5000 35000 120 19.6 574 32 0.52 23.5

A318 120 300 0.78 5000 35000 40 34.7 878 28 0.52 40.3

A319 120 300 0.78 5000 35000 50 33.9 846 29 0.45 39.6

A320-200 120 300 0.78 5000 35000 55 35.9 771 27 0.44 40.7

A321 120 300 0.78 5000 35000 60 34.8 716 28 0.41 39.3

A330-200 120 300 0.82 5000 35000 170 5.88 1010 55 0.44 13.7

A330-300 120 300 0.82 5000 35000 170 5.89 1010 54 0.44 13.6

A340-200 120 300 0.82 5000 35000 190 6.36 949 54 0.41 13.7

A340-300 120 300 0.82 5000 35000 190 6.34 948 54 0.41 13.6

B727 120 300 0.84 5000 30000 50 6.45 4580 83 0.54 37.3

B737-200 120 300 0.73 3000 35000 30 62.0 351 14 0.64 59.4

B737-300 120 300 0.73 3000 35000 40 56.4 328 15 0.56 54.7

B737-400 120 300 0.73 3000 35000 40 56.3 329 15 0.56 54.5

B737-500 120 300 0.75 3000 35000 40 56.4 303 14 0.57 54.3

B737-600 120 300 0.78 3000 35000 40 45.4 420 18 0.57 45.3

B737-700 120 300 0.78 3000 35000 50 42.4 374 19 0.54 42.4

B737-800 120 300 0.78 3000 35000 50 42.2 350 18 0.57 41.9

B747-200 140 300 0.85 5000 40000 250 -2.41 2230 97 0.65 11.5

B747-300 140 300 0.85 5000 40000 200 2.27 1630 81 0.69 13.3

B747-400 140 300 0.85 5000 40000 250 -7.78 3260 120 0.62 10.2

B747SP 140 300 0.85 5000 40000 250 7.44 644 48 0.74 12.4

B757-200 140 300 0.8 3000 40000 100 29.2 298 22 0.55 30

B757-300 140 300 0.8 3000 40000 100 28.9 292 21 0.55 29.7

B767-200 140 300 0.8 3000 40000 110 12.8 918 46 0.65 19.8

B767-300 140 300 0.8 3000 40000 100 13.1 821 42 0.69 19.4

B767-400 140 300 0.8 3000 40000 150 12.9 701 45 0.54 18.3

B777-200 140 300 0.82 3000 40000 170 12.6 198 21 0.72 13.0

B777-300 140 300 0.82 3000 40000 210 13.1 147 19 0.65 12.9

BAC111-200 120 280 0.7 3000 30000 30 55.8 924 27 0.54 60.1

BAC111-475 120 280 0.7 3000 30000 30 50.6 930 28 0.54 55.3

DC10-30 150 300 0.82 5000 30000 200 -6.45 4080 130 0.56 15.0

Electra 100 350 0.7 5000 30000 30 48.9 220 9.1 0.57 41.2

Fokker-100 130 280 0.7 3000 30000 35 52.9 917 27 0.52 57.2

KingAir 100 110 200 0.6 9000 25000 3 70.6 2280 89 0.74 223.

L1011-500 120 300 0.83 5000 35000 150 11.7 712 47 0.59 17.1


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C.1.2 EddyDissipationRate(EDR)

DetailsoftheEDRalgorithmandtheencodingprocesswillbeprovidedinafuturesupplementtothis

standard.


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C.2 AtmosphericWaterVaporContent

Dependingonthewatervaporsensorinstalled,thesoftwarewillbecapableofreportingatmospheric

watervaporcontentfordownlinkin3ways:

1. Mixingratio(r):definedtobetheratioofthemassofwatervaporcontenttothemassofdryair

ofanairsample.Theunitsofrareg/kg.

Resolution:1x103

g/kg.

Range:0to38g/kg.

2. Relativehumidity(RH):definedtobethedensityofwatervaporpresentintheatmosphere

expressedasapercentageofthedensityofwatervaporpresentwhentheairsampleis

saturated(airpressureandtemperatureheldconstant).Thatis:

RH=100x(densityofactualwatervapor/densityofsaturatedwatervapor)

Resolution:0.1%.

Range:0to100%

3. Dewpointtemperature(DPT):thetemperaturetowhichairmustbecooledinorderforitto

becomesaturated(airpressureheldconstant.TheunitsofDPTaredegreesCelsius(C).

Resolution:0.1C

Range: 99to49C

Thesoftwarewillrequireaconfigurationparametertodeterminefromwhichsensorthewatervapor

contentshouldbeacquiredand,asaconsequence,howthewatervaporcontentshouldbeencoded.

WatervaporcontentwillbereportedinthedownlinkmessageasnnnnnQ.Wherennnnisthecoded

watervaporcontentandQisaqualitycontrolparameter.ThevalueofQwillbedependentonthetype

ofsensoremployedandtheunitsinwhichthewatervaporcontentisreported.

Table19:WaterVapourConfigurationCriteria

WATERVAPORSENSOR CONFIGURATIONPARAMETER DOWNLINKFORMAT(NNNNN) QCFORMAT(Q)

NONE 0 ///// 9

WVSSII 1 MIXINGRATIO SEETABLE20

? 2 HUMIDITY U

? 3 DEWPOINTTEMPERATURE D

Inordertoobtainthehighestqualitywatervaporcontentdataontheground,itisalwayspreferableto

downlinkthewatervaporsensoroutputvariableasprovidedratherthanconvertingtooneofthetwo

alternativederivedvariables,e.g.ifthesensorprovidesmixingratio,thenthatiswhatshouldbe

reportedratherthanconvertingtorelativehumidityordewpointtemperatureforreporting.

AtthetimethisspecificationwaspreparedonlydetailsontheWVSSIIsensorwereknown.


42/49


C.2.1 TheWVSSIISensor

C.2.1.1 Introduction

ThesecondgenerationWaterVaporSensingSystem(WVSSII)forcommercialaircraftusesadiodelaser

fortheaccuratemeasurementofwatervaporinformation.Thewatervaporinformationavailableisthe

massatmosphericwatervapormixingratioinkilogramsperkilogram(kg/kg).

TheWVSSIIhasaSystemsElectronicsBox(SEB)thatsendsthemixingratioinARINC429message(Octal

Label303)andbitsinOctalLabel270(relatedtoQvalues)totheavionicsbox(DFDAUorequivalent).

FirststepistocheckthestatusbitsinARINC429messageLabel270(seeSectionC.2.1.4below).If,asa

resultofthestatusbitchecks,theQvaluehasbeensetto2,3,4,or5,thennocalculationismadeand

thedatavaluesformixingratioaresetto(/////)asinSectionsC.2.1.3andC.2.1.4 below.

Ontheotherhand,iftheQvaluehasnotbeensetbytheabovebitchecking,thentheQvalueissetto0

andcalculationsproceedasinSectionC.2.1.2below.Theencodingofthemixingratiovaluethen

proceedsasinSectionC.2.1.3below.

C.2.1.2 CurrentInputVariablesandCalculation

ThevariablesthatareinputtotheprocessingintheDFDAUareasfollows:

Ts: statictemperatureexpressedindegreesKelvin;i.e.,add273.15todegreescentigrade

Ps: staticpressureexpressedinPascals;i.e.,ifpressureinmillibarsorhPa,thenmultiplyby100

NotethatthismaybeobtainedasSTATICPRESSUREorcalculatedfromPRESSUREALTITUDE.

r: (mixingratioinkg/kg). ObtainedfromdiodelaseroftheWVSSIIissuppliedindigitalformtothe

DFDAUatarateofonceeverytwoseconds.

Themixingratioisusedintheobservationbuttherelativehumidity(RH)isusedasacontrolvariable.

Withtheaboveinputvariables,thecalculationofRHisperformedonceeverytwoseconds(usingthe

latestpressureandtemperature)asfollows:

Step1: Calculatewatervaporpressure(e)fromequation(1)

e = (Ps) ( r )/ (r + 0.62197) (1)

Step2: Calculatesaturationvaporpressure(es)fromequation(2)

es= 10 ** [(10.286 Ts 2148.909) / (Ts 35.85)] (2)

Step3: CalculateRHfromequation(3)


43/49


RH = (e/es)(100) (3)

Step4:RoundtheRHvaluetothenearestinteger

Add0.5tothefloatingpointRHvalue,andthentruncatethevaluetoaninteger.

Step5: IFRHlessthan101%,THEN

(i) Presentthemixingratiointhe5charactercode(NNNNN)accordingtoSectionC.2.1.3below.

(ii) Set the control character (Q) in the water vapor information field (NNNNNQ) to Q = 0 (see

SectionC.2.1.4below).

IFRHequaltoorgreaterthan101%,THEN

(i) Presentthemixingratiointhe5charactercode(SectionC.2.1.3below)

(ii) SetQ=1(SectionC.2.1.4below)

C.2.1.3 Presentingthe5-characterMixingRatioField

ThemassmixingratioisbroadcastfromthespectraSensorsWVSSIIsensoronARINC429label303.For

detailedinformationseeSpectraSensorsDWGNo.0102100027,REV.C

ThemassmixingratioiscomputedwithintheWVSSIIsoftwareasafloatingpointnumberinkg/kg.In

ordertorepresentthisnumberasanintegervariableinthe32bitARINCword,thisnumberismultiplied

by220andsendtotheavionicsbox.Soinordertousethevalueneedstobedividedby2

20beforethe

datacanbeencoded.

Thewatervaporinformationispresentedasasixcharacterfield(NNNNNQ)wherethefirstfive

charactersareintegers(NNNNN)withthefollowingmeaning:

NNNNN = N1N2N3N4N5= N1 N2 N3 N4x 10(-3 N5)

Example:12345=1234x1035 =1234x108kg/kg


44/49


C.2.1.4 TheQualityControlCharacter(Q)

ThevalueQisaqualitycontrolcharacteranditsultimatenaturehasthemeaningdefinedintheTable

below.

Table20

:WVSII

Quality

Control

Parameter

Q SystemState SoftwareLogic DataOutput

0 Normaloperation Air/Ground=Air NNNNN0

1 RHgreaterthanorequalto101% RH>thanor=to101% NNNNN1

2 Inputlaserpowerlow Laser


45/49


(/////)andtheQissetto8sothe6charactercodeis/////8.


46/49


AppendixD DataCompression

Inordertominimizethenumberofcharacterinamessageandtherebytransmissioncost,twocodingtechniquesareappliedtothemessagecontents.Thefirsttechniquecodescodessomenumericvalues

intheremainingobservationsasdeltachangesfromtheirpreviousvaluesthisisasavingbecausemost

ofthequantitiesarephysicalvaluesthatvaryslowlywithtime. Thesecondtechniquecodesallinteger

numericvaluesinthemessageintothefullsetofavailableprintablecharacterse.g.arangeof19to

+20canbemappedonto40printablecharacters,thesocalledbase40compression.

D.1 Base-40Compression

Abase40datacompressionschemecanbeappliedtotheintegervaluesinthemessage.Theinteger

valuesaremappedto40printablecharactersaccordingtoTable21

Table21:Base40ConversionChart

.

0 1 2 3 4 5 6 7 8 9

0X 0 1 2 3 4 5 6 7 8 9

1X A B C D E F G H I J

2X K L M N O P Q R S T

3X U V W X Y Z : , .

Findtherangethatthevaluetocompresswillfallinto. [0(40^y)/2,(40^y)/21]willbetheformoftherange,whereyisthesmallestinteger=>1tomakethevaluetocompressfallintotherange

(seeTable22).Addthebase40offsetprovidedinNotes:


2. Normal means the data is not compressed. Compressed means the data is encoded using the









Table24and

.Thebase40offsetisaddedtotheintegervaluetoensureonlypositiveintegers.Table25

Takethenewvalueandconverttoabase40characterstring.


47/49


Table22:DynamicRanges

CHARACTERSREQUIRED(YVALUE) MINIMUMVALUE MAXIMUMVALUE

1 20 19

2 800 799

3 32,000 31,999

4 1,280,000 1,279,9995 51,200,000 51,199,999

6 2,048,000,000 2,047,999,999

Importantitemstonote

Valuesoutsideoftherange[2,048,000,000..2,047,999,999]cannotbeconvertedandshallreturn/;

Decompressingastringcontainingnonvalidcharacterswillreturn2147483647;


48/49


D.2 Messageformat,Compressed

WhenapplyingdeltaBase40theformatforthemessageformatchangesasfollows:

Table23:Header,compressed

LINE

NUMBER

CHARACTER

NUMBER

#OFCHAR CONTENT FORMAT NOTES

1 13 3 AMDARMESSAGEVERSION A04

2 126 1TO26 OPTIONALPARAMETERINDICATION #ORATHRUZ SEEOPTIONAL

PARAMETERS

3 17 8 AMDARAIRCRAFTIDENTIFIER AAAAAAAA 1

3 8 1 NORMAL(N)ORCOMPRESSED(C) NORC 2

3 9 1 TIMEBASED(0)ORPRESSUREBASEDSCHEME

(1)

0OR1

3 10 1 ALTITUDEREFERENCE:PRESSUREALTITUDE

(P)ORBAROMETRICALTITUDE(B)

PORB 3

3

1114

4

DEPARTUREAIRPORT

AAAA

4

3 1518 4 ARRIVALAIRPORT AAAA 4

Notes:


6. Normal means the data is not compressed. Compressed means the data is encoded using the









Table24:BasicObservationFormat,compressed

CHARACTERSDESCRIPTION TYPE BASE40

OFFSET

ABSOLUTE

RANGE

DELTA

ALLOWED

RANGE FIRST

OBS

SUBSEQOB

S

PHASEOFFLIGHTINDICATOR 10XABSOLUTE N/A N/A N/A 1 1

LATITUDE(INSECONDS) 1XABSOLUTE

9XDELTA

1,280,000

32,000

324000TO

+324000

SECONDS

32000

TO

+31999

SECONDS

4 3

LONGITUDE(INSECONDS) 1XABSOLUTE

9XDELTA

1,280,000

32,000

648000TO

+648000

SECONDS

32000

TO

+31999

SECONDS

4 3

DAY/TIME(UTC) 1XABSOLUTE 0 0TO 0TO 5 3


49/49

9XDELTA 0 2678399

SECONDSINTO

THEMONTH

32000

SECONDS

PRESSUREALTITUDEINTENSOFFEET

(REFERENCESAGAINSTSTANDARD

ICAOATMOSPHERE)

10XABSOLUTE 32,000 100TO

+5,000TENS

OFFEET

N/A 3 3

TEMPERATURE 10XABSOLUTE 800 800TO+799TENTHSOFC

N/A 2 2

WINDDIRECTION 10XABSOLUTE 0 0TO360

DEGREES

N/A 2 2

WINDSPEED 10XABSOLUTE 0 0TO+800

KNOTS

N/A 2 2

TOTALS 23 19

Table25:Optionalparameters,compressed

CHARACTERSDESCRIPTION TYPE BASE40

OFFSET

ABSOLUTE

RANGE

DELTA

ALLOWED

RANGE FIRST

OBS

SUBSEQOB

S

ROLLANGLEFLAG 10XCHARACTER 0 N/A N/A 1 1

EDR 10XCHARACTER N/A N/A N/A 1+8*

1+8*

DEVG 10XABSOLUTE 0 0TO800

TENTHSM/SEC

N/A 2*

2*

TRUEAIRSPEED 10XABSOLUTE 0 0TO999 N/A 3 3

TRUEHEADING(TENTHOFDEGREES) 10XABSOLUTE 0 0TO3590 N/A 3 3

GNSSALTITUDE 10XABSOLUTE 0 100TO

+5,000TENS

OFFEET

N/A 3 3

ANTIICE 10XABSOLUTE 0 0TO2 N/A 1 1

A/CCONFIGURATIONINDICATOR 10XABSOLUTE 0 OTO15 N/A 1 1

WATERVAPOR 10XABSOLUTE 0 0TO99999 N/A 4 4

WATERVAPORQUALITY 10XCHARACTER N/A N/A N/A 1 1

ICING 10XABSOLUTE 0 0TO2 N/A 1 1

TOTALS 21+7*

21+7*

*ThenumberofcharactersdependsonwhetherEDRorDEVGischosenastheturbulenceindicator.IfEDRis

chosen,italsodependsthevalueforEDR.Inthesetotals,DEVGisassumed(2characters),ifEDRischosen,the

totalnumberwouldbe21+7=28