空中领航学(E_06).ppt

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 and instrumentapproaches 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 and visualterminalcharts VTC WheretoFindDetailsofanNDB DetailedinformationforeachNDBispresentedintheERSA Ratedcoverage Position Ident Ident Ident Frequency212KHz NDBdetailsonanERC L NDBdetailsonaVTC BroadcastingStations Broadcastingstationsoperatingintherangeof500 1 600kHzmayalsobereceivedonanADF theycanbedifficulttoidentify youcanbeeasilydistractedbythem theymaybeunreliable and noinformationonrangeispublished 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 and theradiomagneticindicator 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 usinganRBIandaDGistopicturetheADFneedle spositiononthefaceoftheDG ManualRotatable CardADF WhentheADFcardismanuallyalignedwiththeDG theADFneedlewillindicatethemagneticbearingto MBTO theNDB Thetailoftheneedleindicatesthemagneticbearingoftheaircraftfrom MBFROM theNDB Therotatable cardcanstillbeusedasafixed cardsimplyby leaving000setundertheindex Anytimeyoualterheading youmustrealigntheADFcardwiththeDG Arotatable cardADF RadioMagneticIndicator RMI TheRMIdisplayhastheADFneedlesuperimposedonacardthatiscontinuouslyandautomaticallybeingalignedwithmagneticnorth Itisanautomaticversionoftherotatable cardADF anautomaticcombinationoftheDGandRBI TheRMIneedlewillalwaysindicatethemagneticbearingtotheNDB andthetailoftheRMIneedlewillindicatethemagneticbearingfromtheNDB ADFIndicatorswithTwoNeedles AnRMIwithtwoneedles MostRMIshavefunctionswitchesthatallowapilottoselecttheRMIneedletopointateitheranNDBoraVOR UsingtheADFtoObtainPositionLinesfromanNDB TheADFcanbeusedtoassistyouinyourvisualnavigation aswellasbeingthesolemeansofnavigation WecanusetheADFtodothefollowing obtainapositionline tracktoanNDB determineyourpositiondirectlyoveranNDB trackawayfromanNDB interceptaplannedtrack and assessyourpositionabeamanNDB UsingtheADFtoObtainPositionLinesFromanNDB Therearetwoperspectivesfromwhichwecandeterminetherelativepositionsofandaircraftandaradiobeacon Fromtheaircraft asapilotinflightwould whichisthebearingoftheNDBfromtheaircraft and Fromthegroundstation 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 Thevariationinyourareais6 W 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 Witha5 leftWAC 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 Regainingtrackby doublingtheerror 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 TrackingawayfromanNDBwithaWCAof5 intowind 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 sayfrom45 to30 to15 and finally tozeroasthetrackisintercepted Example Interceptingtrack055inboundfromradarvector010 Stepstobetakentointerceptaninboundtrack Orientatetheaeroplane Alteryourheadingtointercepttheintendedtrack TheADFneedlewillcontinuetopointattheNDBandsotherelativebearingwillchange MaintainthemagneticheadingandperiodicallyobservetheRBIastheheadoftheneedlefalls AstheneedlefallstotheexpectedRB i e interceptingtheintendedtrack 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 togiveacombinedsignalthatt