空中领航学(E-06)

北京航空航天大学飞行学院,空中领航学,AirNavigation,课件制作课程讲授,王惠民,NM,340M,AcorrectlytunedADFindicatesthedirectionofaselectedNDBfromtheaircraft.,NDB-ADFCombination,TheNDB(non-directionalbeacon)isagroundradiotransmitter;andtheADF(automaticdirectionfinder)isareceiverintheaircraft.,ThepilotisabletodeterminewithreferencetotheaircraftmagneticheadingapositionlinebetweentheaircraftandNDB.,TheNDB-ADFsystemisusedforthefollowingpurposes:orientation(whereamI?);enroutenavigation(trackingfrompointtopoint);holdingoverspecifiedpoints;andinstrumentapproaches.,Non-directionalbeaconsaresimpleground-basedtransmittersthatradiateanomni-directional(alldirections)signal.NearlyallNDBsinAustraliaoperateonfrequenciesbetween200kHzand400kHz.MostNDBsareprimarilyshort-distancenavigationaids,usefulfordistanceslessthan200nm.,Non-DirectionalBeacon(NDB),Non-DirectionalBeacon(NDB),TwotypesofNDBtransmissionantennas.,ThetransmitterpowerofmostNDBsisbetween100Wand3,000W.,MostNDBsareinstalledinpairs,withamainandstandbyincaseoffailure,andareextremelyreliableaids.CivilAviationSafetyAuthoritypersonnelatnearbyaerodromesmonitortheNDBswithinrange,butNDBsinremoteareasshouldbemonitoredbypilotsandanyfaultsreportedbyradiotoallowearlyrectification.,NDBReliability,NDBfrequencies,identcodesandgeographicalpositionsarefoundinthefollowingpublications:EnRouteSupplementAustralia(ERSA);enroutecharts(ERC);visualnavigationcharts(VNC);andvisualterminalcharts(VTC).,WheretoFindDetailsofanNDB,DetailedinformationforeachNDBispresentedintheERSA.,Ratedcoverage,Position,Ident,Ident,Ident,Frequency212KHz,NDBdetailsonanERC-L.,NDBdetailsonaVTC.,BroadcastingStations,Broadcastingstationsoperatingintherangeof5001,600kHzmayalsobereceivedonanADF.theycanbedifficulttoidentify;youcanbeeasilydistractedbythem;theymaybeunreliable;andnoinformationonrangeispublished.,ComponentsandPrincipleofOperation,AutomaticDirectionFinder(ADF),ThebasicpurposeoftheADFistoindicatetothepilotthedirectionoftheNDBtowhichtheADFistuned.,AutomaticDirectionFinder(ADF),TheADFneedlepointsdirectlytowardstheselectedNDBgroundstation.,ADFcomponents.,ADFreceiver,ADFsingleneedle,ADFdualneedles,Receiver,ThereceiverandassociatedcontrolpanelisusedtotunetheADFtothefrequencyoftheNDBthatyouhaveselectedtouse.,Antenna,ThemodernADFantennasystemactuallyconsistsoftwoaerials:aloopaerialandasenseaerial.,CockpitDisplay,TheADFcockpitdisplayconsistsofacompass,orazimuth,cardplacedverticallyontheinstrumentpanel,withapointerorneedlethatrotatesthroughthefull360.,ADFOperation,Asageneralrule,thefollowingprocedureapplies:Switchon;SelectADFandtunethefrequencyoftheNDB;IdentifythesignalfromtheNDB.ThebestapproachistohaveinyourmindtheMorsecodesymbolsyouexpecttohear,anthenlistencarefullytotheidenttoverifythatyouhavethecorrectNDB;CheckthatitisADFing.,Note:Nevertrustasignalthathasnotbeenaccuratelyidentified.,DifferentTypesofADFIndicator,Toconveyinformationtothepilot,ADFindicatorsusethreedifferentpresentations:thefixed-cardADF,orrelativebearingindicator(RBI);themanuallyrotatablecard,andtheradiomagneticindicator(RMI).,Fixed-CardADF,Onthefixed-carddisplay,theADFneedleindicatestherelativebearingoftheNDBgroundstationfromtheaeroplane.,Afixed-cardADFisarelativebearingindicator(RBI).,ItissometimesconvenienttodescribethebearingoftheNDBrelativetothenoseortailoftheaeroplane.,TheRBIshowsrelativebearings,Eachtimetheaeroplanechangesitsmagneticheading,itwillcarrythefixedcardwithit,buttheneedlecontinuestopointatthestation.Therefore:Witheachchangeofmagneticheading,theADFneedlewillindicateadifferentrelativebearing.,PeriodicallyrealigntheDGwiththemagneticcompass.,Wenormallyflymagneticheadingsusingthedirectionalgyro(DG)asthereferenceinstrument.TheDGmustberealignedwiththemagneticcompassthroughouttheflightatregularintervals.,OrientationusingtheRBI.,Aeroplanemagneticheading,MagneticbearingtoNDBfromaeroplane,RelativebearingofNDBfromaeroplane,MagneticbearingofaeroplanefromNDB,+,=,+/180,=,+,MB130FROM,-,MH280,RB030,=,MB310TO,180,=,MagneticBearingandHowtoVisualiseit,Aquickmethodofdeterminingamagneticbearing(MBTO)usinganRBIandaDGistopicturetheADFneedlespositiononthefaceoftheDG.,ManualRotatable-CardADF,WhentheADFcardismanuallyalignedwiththeDG,theADFneedlewillindicatethemagneticbearingto(MBTO)theNDB.Thetailoftheneedleindicatesthemagneticbearingoftheaircraftfrom(MBFROM)theNDB.Therotatable-cardcanstillbeusedasafixed-cardsimplyby,leaving000setundertheindex.,Anytimeyoualterheading,youmustrealigntheADFcardwiththeDG.,ArotatablecardADF,RadioMagneticIndicator(RMI),TheRMIdisplayhastheADFneedlesuperimposedonacardthatiscontinuouslyandautomaticallybeingalignedwithmagneticnorth.Itisanautomaticversionoftherotatable-cardADFanautomaticcombinationoftheDGandRBI.,TheRMIneedlewillalwaysindicatethemagneticbearingtotheNDB,andthetailoftheRMIneedlewillindicatethemagneticbearingfromtheNDB.,ADFIndicatorswithTwoNeedles,AnRMIwithtwoneedles.,MostRMIshavefunctionswitchesthatallowapilottoselecttheRMIneedletopointateitheranNDBoraVOR.,UsingtheADFtoObtainPositionLinesfromanNDB,TheADFcanbeusedtoassistyouinyourvisualnavigation,aswellasbeingthesolemeansofnavigation.WecanusetheADFtodothefollowing:obtainapositionline;tracktoanNDB;determineyourpositiondirectlyoveranNDB;trackawayfromanNDB;interceptaplannedtrack;andassessyourpositionabeamanNDB.,UsingtheADFtoObtainPositionLinesFromanNDB,Therearetwoperspectivesfromwhichwecandeterminetherelativepositionsofandaircraftandaradiobeacon:Fromtheaircraft,asapilotinflightwould,whichisthebearingoftheNDBfromtheaircraft;andFromthegroundstation,whichisthebearingoftheaircraftfromtheNDBandmaybenecessaryifyouwanttoplotthepositionoftheaircraftonachart.,UsingtheRBI(Fixed-cardADF),AfewexamplesthatshowhowtheRBI(i.e.fixed-cardADF)maybeusedtoestablishbearingsandpositionlines:,Followthroughthestepsinsequence:,AnEasierMethodofDeterminingMagneticBearing,Relativebearingarenormallyspecifiedusingthemethod(clockwisefromthenose).Theycanalsobethoughtofaseitherleftorrightofthenose(orthetail).,QuadrantsforconvertingRBstoMBs,Usingthismethod,youmustrememberthatoffthenosegivesmagneticbearingsTOtheNDB,offthetailgivesbearingsFROMtheNDB.,UsingtheRotatable-CardADFortheRMI,ApartfromensuringcorrectsynchronisationwiththemagneticcompassandcorrecttuningandidentificationoftheNDB,allyouhavetodoisreadoffthemagneticbearingdirectly.,ThemagneticbearingtoanNDBstationisreadfromtheheadoftheneedle,andthemagneticbearingfromtheNDBisreadfromthetail.,OrientationwithanRMIisstraightforward.,PlottingtheADF-NDBPositionLine,ThebearingsobtainedfromanADForanRMIaremagneticbearings.Beforetheycanbeplottedonachart,theymustbeconvertedintotruebearingsbycorrectingforthemagneticvariationthatappliesinthevicinityoftheaircraft.,Strictlyspeaking,itisthemagneticvariationattheaircraftpositionwhichisapplied,andnotthevariationattheNDBstationitself.,WhenplottingADFbearingsonachart,thefollowingstepsshouldbefollowed:,DeterminethemagneticbearingfromtheNDB.Determinethemagneticvariationinthevicinityoftheaircraft.ConvertthemagneticbearingtothecorrespondingtruebearingfromtheNDB.Byaligningaplotterorprotractorparallelwiththenorth-southmeridianatthestationconcerned,plottheresultingpositionlineradiatingfromtheNDB.,PlottingapositionlinefromanNDB.,YouaresteeringMH280andobtainanADFreadingofRB050.Thevariationinyourareais6W.Determinethetruebearing(TB)toplotfromtheNDBstation.,MH280+RB050=MB330TO,-180,=MB150FROM,-6WVAR,PlotTB144FROM,TrackingProceduresUsingtheADF,WhenflyingtowardsanNDB,theADFneedlewillpointaheadoftheaircraft(approximatelyRB000),andwhenflyingawayfromanNDB,theADFneedlewillpointbehindtheaircraft(approximatelyRB180).AsanaircraftapproachesanNDBgroundstation,theADFneedlewillbecomemoreandmoresensitive.Onpassingoverhead,theneedlewillswingfrompointingaheadtopointingbehind(infact,itmayoscillatewidelyduringstationpassage,completingseveralcircuitsoftheindicatorcardinrandomdirections).,TrackingProceduresUsingtheADF,TrackingTowardsanNDBUsingtheRBI,WithNoCrosswindEffect,Ifthereisnocrosswindtoblowtheaircraftofftrack,wecansettheheadingastrack,andtheaircraftshouldflydirectlytothedestination.,Trackinginboundwithnocrosswindeffect.,InaCrosswind,WithNoCorrectionforDrift,Crosswindhascausedtrackerror.,Thedifferencebetweenhomingandtracking.,Homingisaprocedurethatshouldnotbeused.Thecorrectprocedureistoregaintheintendedtrack,andalterheadingtotheleft(right)toallowforright(left)drift,thecorrectamountofdriftbeingfoundbytrialanderrororbycalculation.,ItismorethanlikelythatthewindeffectwillchangeasyoutracktowardsanNDB,andregularadjustmentstoheadingwillthereforeberequired.Withpractice,youwillfinditquiteeasytoassessthedriftandtheconsequentwindcorrectionangle(WCA)tobeappliedsoastoremainmoreorlessonyourintendedtrackintotheNDB.,WithCorrectDriftCorrectionApplied,Witha5leftWAC,youwouldexpecttoseetherelativebearingoftheNDBfromtheaircraft(RB005)remainunchangedasyoutrackedinontrack096steeringMH091.,WithIncorrectDriftCorrectionApplied,Ifanincorrectdriftcorrectionismade,thenyouwilldriftofftheplannedtrack;thatis,theRBindicationandtheMBTOtheNDBwillchange.Ifasteadyheadingisbeingflown,thenandivergencefromtrackwillbecomeobviousthroughagraduallychangingrelativebearing,withtheADFneedlemovingleftorrightdownthedial.,Driftistheanglebetweenheadingandthetrack.TheperfectWCAwillcounteractanydriftexactly,andthetrackmadegoodwillfollowtheintendedorplannedtrack.,HowtoRegainandThenMaintainTrack,IftherewasonlyashortdistancetoruntotheNDBstation,youcouldtrackdirectlytoitfromthepresentposition.,FlyinganewtracktotheNDB.,HowtoRegainandThenMaintainTrack,Regainandmaintaintheplannedtrack.,Iftherewasalongdistancetorun(say20nm),youmightdecidetotakeuptrackasheading,lettingthewinddriftyoubackontotrack,andoncebackonit,steeracorrectMH,whichwouldallowforarightdrift.,Headofneedlefallingright,turnright;Headofneedlefallingleft,turnleft.,If,whensteeringasteadymagneticheading,theADFneedleindicatesaconstantrelativebearingnearthetopofthedial,thenyouaretrackingdirectlytotheNDBandnocorrectiontoheadingisnecessary.,IfMH+RB=constantMB,trackingisgood.,Justhowbigacorrectionyouneedtomakedependsuponhowfaryouhavestrayedoffyourintendedtrack.Asimplemethodistodoubletheerror.,Regainingtrackbydoublingtheerror,andmaintainingtrackthereafter.,WhatToDoifUncertainofWindEffect,Ifthewinddirectionandstrengthisnotobvious,thenthebesttechniqueistoinitiallysteertrackasheading,makingnoallowancefordrift.TheeffectofthewindwillbecomeobviousastheADFneedlemovestotheleftorright.Observetheresults,andthenmakeappropriateheadingadjustmentstomaintaintrack.,Ifuncertainofwind,initiallysteertrackasheading.,TrackingOveranNDBUsingtheRBI,TheADFneedlewillbecomemoreandmoresensitiveastheNDBstationisapproached.Foraverypreciseoverheadtobeachieved,youmustbepreparedtoincreaseyourscanrateastheNDBisapproachedandtomakesmallercorrectionsmorefrequently.,ClosetothestationandjustpriortopassingovertheNDB,youshould,atthispoint,relaxalittleandsteerasteadyheadinguntiltheaeroplanepassesovertheNDBindicatedbytheADFneedlemovingtowardthebottomofthedial.HavingpassedovertheNDB,trackingfromtheNDBshouldbecheckedandsuitableadjustmentsmadetoheading.,GoodADFtracking,ReasonableADFtracking,PoorADFtracking,WhentheADFneedlebecomesextremelyactiveandthenfallsrapidlytothebottomofthedial,itindicatesthatyouhavepasseddirectlyovertheNDB.IftheADFneedlemovesgraduallytoonesideandslowlyfallstothebottomofthedial,thenthisindicatesthatyouarepassingtoonesideofthebeacon.TherateatwhichtheneedlefallsindicatesyourproximitytotheNDB.Timewhenover(orabeam)theNDBwithnoWCAcanbetakenastheneedlefallsthroughtheapproximate090or270position.,TrackingAwayfromanNDBUsingtheRBI,WhentrackingawayfromanNDB,theheadoftheADFneedlewilllietowardthebottomofthedial.,WithNoCrosswindEffect,IfyoutrackovertheNDBandthensteertrackasheading,youwilltrackdirectlyawayfromtheNDBwiththeheadoftheADFneedlesteadyon180,andthetailoftheADFneedlesteadyatthetopofthedialon000.,TrackingawayfromanNDBwithnocrosswindeffect.,InaCrosswind,WithCorrectDriftCorrectionApplied,TrackingawayfromanNDBwithaWCAof5intowind.,MBFROMNDB=MH+/-deflectionofthetailoftheneedle.,WithIncorrectDriftCorrectionApplied,WhereasinaccuratetrackingtoanNDBisindicatedbytheADFneedlefalling,incorrecttrackingawayfromanNDBcanoccurwiththeADFneedleindicatingasteadyreading.,TrackingawayfromanNDBwithincorrectdriftcorrectionapplied.,TrackingAbeamanNDB,NilDrift,Inthiscase,headingisequaltotrack.Attheabeamposition,theADFwillindicateeitherRB090orRB270.,WithDrift,Ifacrosswindcomponentisactingontheaircraft,thentheheadingwilldifferfromthetrackbytheamountofdriftbeingexperienced.,RBIindicationsattheabeampositionwithdriftcorrectionapplied.,InterceptingaTrackUsingtheRBI,WhereamI?WheredoIwanttogo?HowdoIgetthere?,OrientatetheaeroplanerelativetotheNDB,andtotheplannedtrack.Turntotakeupasuitableinterceptheading,afterconsideringwhereyouwanttojointheplannedtrack.Maintaintheinterceptheading.Asyoucomeuptotheinterceptpoint,turntotheplannedtrack,andapplyasuitableWCAtomaintainit.,VisualisingWhereYouAreandWhereYouWanttoGo,TheDGcanassistgreatlyinvisualisingthesituation.WhatifyouwishtointercepttheintendedtrackinboundtotheNDB?Allyouneedtodoisvisualisetheintendedtrackontheheadingindicator.Withamodelaeroplaneonthetailoftheneedletrackingasintended,itbecomequiteclearwhatturnsarenecessarytointerceptthetrack.,Ifyoubecomedisoriented,asimpleprocedureistotakeuptheheadingoftheintendedtrack.Eventhoughnotontrack,theaeroplanewillatleastbeparalleltoit,andtheADFneedlewillindicatewhichwaytoturntointerceptit.,Visualisingtheintercept.,Aninefficientinterceptoftrack.,Differentinterceptoftrack.,InterceptinganInboundTrack,NM,Example:Interceptingtrack340inboundfromsouthofthestation.*,*Note:Anaeroplanetakessomedistancetoturn,andsoyoushouldanticipatetheintendedtrackbycommencingtheturnontotrackjustbeforeMB340isreached.YoucandothisbyobservingtherateatwhichtheADFneedlefallstoward-060andcommencetheturnaccordingly.,Anothermeansofachievingasmoothinterceptistoreducetheclosingangleastheinboundtrackisapproached,sayfrom45to30to15and,finally,tozeroasthetrackisintercepted.,Example:Interceptingtrack055inboundfromradarvector010.,Stepstobetakentointerceptaninboundtrack:,Orientatetheaeroplane.Alteryourheadingtointercepttheintendedtrack.TheADFneedlewillcontinuetopointattheNDBandsotherelativebearingwillchange.MaintainthemagneticheadingandperiodicallyobservetheRBIastheheadoftheneedlefalls.AstheneedlefallstotheexpectedRB(erceptingtheintendedtrack),turntotakeuptheintendedtracktotheNDB,allowingfortheestimatedcrosswindeffectontracking.,Example:Radarvector340tointercepttrack280outbound.,InterceptinganOutboundTrack,Stepstobetakentointerceptanoutboundtrack:,Orientatetheaeroplane.Considertheintercept.MonitortheinterceptbysteeringasteadyheadingandperiodicallycheckingtheRBItoseethetailoftheneedlerising.Astherequiredoutboundtrackisapproached,indicatedbythetailoftheneedle,turntopickitup,allowingfortheestimatedcrosswindeffectontracking.PeriodicallycheckthatMH+/-ADFtail=MBFROMNDB.,LimitationsandAccuracyoftheNDB-ADFCombination,Limitations,AsaresultofvariouslimitationsaffectingthesignalstransmittedbyanNDB,thebearingstakenbyanADFareliabletobeinerror.,NightEffect,Theindirectskywavemixeswiththedirectgroundwave(i.e.themainpathtakenbyradiowavesfromtheNDBgroundtransmitter,whichisalongthesurfaceoftheearth.)togiveacombinedsignalt