air line pilots association, international national

Submissionofthe

AirLinePilotsAssociation,International

tothe

NationalTransportationSafetyBoard

RegardingtheAccidentInvolving

DeltaAirLines1086

MD-88

DCA15FA085

NewYork,NY

March5,2015

AirLinePilotsAssociation,InternationalDeltaAirLines1086Submission

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TableofContents

ExecutiveSummary........................................................................................................................1

1.0 FactualInformation.................................................................................................................31.1 HistoryofFlight...............................................................................................................3

2.0 Operations..............................................................................................................................42.1 Weather...........................................................................................................................42.2 RegulationsforDispatchinganAircraft...........................................................................52.3 CrewExpectationofRunwayCondition..........................................................................62.4 Approach.........................................................................................................................62.5 LandingDistanceAssessment..........................................................................................72.6 RunwayConditiononthePier.........................................................................................82.7 MD-88SpoilerSystem.....................................................................................................92.8 MD-88AutoBrakeSystem.............................................................................................102.9 Antiskid..........................................................................................................................112.10 AircraftPerformanceAfterTouchdown........................................................................112.11 ThrustReversers............................................................................................................132.12 ManualBraking..............................................................................................................142.13 UseofRudder................................................................................................................152.14 Control-ColumnPositionvs.ElevatorPosition..............................................................152.15 LiftingForcesontheRearSection.................................................................................162.16 DiscrepanciesinManualsandGuidance.......................................................................172.16.1 UseofCautionandWarning..................................................................................172.16.2 EPRLimitation........................................................................................................182.16.3 ThrustReverseDeploymentandEngineAcceleration...........................................182.16.4 Control-ColumnUsage...........................................................................................192.16.5 DirectionalControlLossonSlipperyRunways.......................................................202.16.6 Training...................................................................................................................22

2.17 SpecialWinterOperationsAirport(SWOA)...................................................................24

3.0 Airport...................................................................................................................................243.1 AirportInformation.......................................................................................................243.2 LGASnowRemovalPlan................................................................................................243.3 ContinuousRunwayMonitoringRequirement..............................................................263.4 Post-CrashFrictionTesting............................................................................................27

4.0 SurvivalFactors.....................................................................................................................284.1 Post-AccidentCrewActions...........................................................................................284.2 PassengerConduct........................................................................................................29


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5.0 ChangesBeingImplementedbytheFAADuetotheTALPAARC.........................................29

6.0 Conclusions...........................................................................................................................30

7.0 Findings.................................................................................................................................33

8.0 Recommendations................................................................................................................35


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TableofFigures

Figure1:DeltaMD-88/90OperationsManual—NormalProcedures,StabilizedApproach........................7

Figure2:Delta10-7Page,CautionforLandingsonLGAPier.......................................................................8

Figure3:DeltaMD-88/90OperationsManual,AutoBrakeControlPanel................................................10

Figure4:DeltaMD-88/90OperationsManual,AutoBrakeSelectorandDecelerationRates...................11

Figure5:PassengerPhotographoutoftheLeftSideWindowatthe500-FootRunwayMarker..............13

Figure6:ElevatorandControl-ColumnPositionAfterNoseGearTouchdown.........................................16

Figure7:MD-88/90OperationsManualVol1—PageP1.2.4,Definitions.................................................17

Figure8:DeltaFCTM,GuidanceReverseThrustOperationsinCrosswindConditions..............................22

Figure10:LGATruckwithRunwayFrictionTester....................................................................................27

Figure11:DeltaMD-88OperationsManual,EvacuationChecklist...........................................................28


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Acronyms/Definitions

AA AmericanAirlines

AC AdvisoryCircular

ACARS AircraftCommunicationsAddressingandReportingSystem

ACM AirportCertificationManual

AGL AboveGroundLevel

AIM AeronauticalInformationManual

AOL AllOperatorLetter

AOM AircraftOperatingManual

APU AuxiliaryPowerUnit

ARC AviationRulemakingCommittee

ARFF AircraftRescueandFirefighting

ASR AirportSurveillanceRadar

ATC AirTrafficControl

ATCT AirTrafficControlTower

ATIS AutomaticTerminalInformationService

ATL Hartsfield-JacksonAtlantaInternationalAirport

CAWS CentralAuralWarningSystems

CFME ContinuousFrictionMeasuringEquipment

CFR CodeofFederalRegulations

CRJ CanadairRegionalJet

CVR CockpitVoiceRecorder

DAB DaytonaBeachInternationalAirport

DAL DeltaAirLines

EPR EnginePressureRatio


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EST EasternStandardTime

FAA FederalAviationAdministration

FCTM FlightCrewTrainingManual

FDR FlightDataRecorder

FO FirstOfficer

G AccelerationofGravity

Hz Hertz

ICAO InternationalCivilAviationOrganization

IFR InstrumentFlightRules

ILS InstrumentLandingSystem

IMC InstrumentMeteorologicalConditions

LGA LaGuardiaAirport

LOA LetterofAgreement

MAT MarineAirTerminal

METAR MeteorologicalAerodromeReport

N1 RotationalSpeedofLowPressureCompressor

NOTAM NoticetoAirmen

NTSB NationalTransportationSafetyBoard

NWS NationalWeatherService

ODM OperationalDataManual

PA PublicAddress

PF PilotFlying

PIREP PilotReport

PM PilotMonitoring

PSEU ProximitySwitchElectronicsUnit


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QAR QuickAccessRecorder

RCAM RunwayConditionAssessmentMatrix

SMR SurfaceMovementRadar

SPOT SpecialPurposeOperationalTraining

SWOA SpecialWinterOperationsAirport

TALPA TakeoffandLandingPerformanceAssessment

UAL UnitedAirlines

UTC CoordinatedUniversalTime

Vref ReferenceSpeed

WOW WeightonWheels


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ExecutiveSummary

OnMarch5,2015,atabout1102EasternStandardTime(EST)1,aBoeingMD-88,N909DL,operatedasDeltaAirLines(DAL)Flight1086,landedonRunway13atLaGuardiaAirport(LGA),NewYork,N.Y.,exitedtheleftsideoftherunway,contactedtheairportperimeterfence,andcametorestwiththeaircraftnoseonanembankmentoverhangingFlushingBay.The129passengersreceivedeitherminorinjuriesorwerenotinjured,andthe3flightattendantsand2flightcrewwerenotinjured.Theaircraftwassubstantiallydamaged.Flight1086wasaregularlyscheduledpassengerflightfromHartsfield-JacksonAtlantaInternationalAirport(ATL)operatingundertheprovisionsof14CodeofFederalRegulations(CFR)Part121.Instrumentmeteorologicalconditions(IMC)prevailed,andaninstrumentflightrules(IFR)flightplanwasfiled.

Thefollowinganalysisoutlinestheeventand“findings”leadinguptotheaccidentandprovidesrecommendationstopreventsimilareventsfromoccurringinthefuture.Theanalysisofthiseventidentifiesseveralcontributingfactors,includingflightcrewtraining,guidanceprovidedinthemanuals,andairport-relatedissues.Thisaccidentcannotbereducedtoonespecificcause;rather,achainofeventsledtothisaccident.

DuringtheflightfromATLtoLGA,theflightcrewwasdiligentinobtaininginformationontheconditionstheywouldencounteruponarrivalatLGA.Severaltimesthecrewrequestedbrakingactionreportsanddiscussedissueswithlandingonacontaminatedrunway.Thecrewcompletedanextensiveapproachbriefingandselectedthemostconservativeconfigurationforlandingonacontaminatedrunway.Whentheflightcrewhadtherunwayinsight,itwasnotwhattheyexpected.Bothpilotshadapictureintheirmindthattheywouldseeablackrunway,notonecompletelycoveredinsnow.

Thecaptainadjustedhisaimpointtolandtheaircraftontherunwaysoonerthanbriefed,inaccordancewiththeDeltamanuals.Theaircrafttoucheddownonthepierthathadhadbeenexposedtofreezingfogconditionsforthreehourspriortotheaccidentandwasaccumulatingice.Thewheelsdidnotspinupontouchdown,andthespoilersdidnotautomaticallydeploy.Whenthefirstofficer(FO)manuallydeployedthespoilers,maximumautobrakewasactivated,andtheanti-skidprotectioncouldnotactivatebecausetherewasnowheelspin-up.

Duringthelandingroll,thetargetenginepressureratio(EPR)of1.3inreversethrustwasexceeded,whichdegradeslongitudinalcontrolandcancauserudderblanking.TheguidanceintheDeltamanualsdidnotestablishahardmaximuminthrustreverseEPRsetting,buttargetvalueswerelisted.

Theairport,contrarytothebroadcastedAutomaticTerminalInformationService(ATIS),didnotsandortreattherunwayswithsolidchemicals,exceptearlierinthemorningpriortotheairportopening,whichwasfivehoursbeforetheaccident.Whentherunwaywasbroomedabout40minutespriortotheaccident,allappliedchemicalswerebrushedoff,andnochemicalswerereapplied.Additionally,the

1AlltimespublishedinCoordinatedUniversalTime(UTC)areconvertedtoESTforconsistencywithNationalTransportationSafetyBoard(NTSB)factualreports(UTC=EST+5hours).


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runwaywasneversanded.Italsoshouldbenotedthatthesnowfallratehadsignificantlyincreasedaroundthetimeoftheaccident,andtherunwaywascoveredwithsnow.Aprecedingaircraftthatlandedabout20minutespriortotheaccidentflightreportedpoorbraking,butnoactionwastakenbytheairport.

Throughouttheentiremorningandthroughchangingconditions,theairportneveradjustedthefieldconditionreportstating0.25inchesofsnowonallsurfaces.Basedontheinformationprovidedtotheflightcrew,theyexpected“good”brakingaction.SincetheaccidentandbasedonworkdonefollowingtheSouthwestAirlinesaccidentattheMidwayAirportinChicago,Ill.,in2005,anewAdvisoryCircular(AC25.32)wasissuedinDecember2015.InthisnewAC,theconditionsprovidedtotheflightcrewof0.25inchesofsnowwouldcorrelatewith“medium”brakingaction.Mediumbrakingactionwouldhaveresultedinalandingdistanceof7,000feet,whichexceededtherunwaylengthinLGA,andtheaircraftwouldnotbeallowedtoland,inaccordancewiththeDeltaOperatingDataManual(ODM).

Theairportstrictlyreliedonpilot-reportedbrakingactiontodeterminetheconditionoftherunways.Whilethisisinaccordancewithregulationandguidanceatthetimeoftheaccident,itdidnotprovidetheflightcrewwiththebestpossibleassessmentoftherunwayconditions.

Inconclusion,ALPAagreeswiththeNTSBPerformanceStudyconclusion,whichstates:“Thedatawasincompleteortheeffectsoftheseforcesontheaircraftwerenotmeasuredand/oraccuratelymodeledfortheexactcontributionofeachtobedetermined.Whatdatawasavailabledidnotmakeanysingleeventorenvironmentalfactorseemlikelyonitsowntobeabletoimparttheyawingmomentexperiencedbytheaccidentaircraft.Itislikelythatacombinationofasymmetricthrust,crosswind,andrunwayfrictioncausedtheaircrafttodeviatefromtherunwayheading.”Therewasnosingleeventthatcausedthisaccident,butaseriesoffactorsallplayedarole.


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1.0 FactualInformation

1.1 HistoryofFlight

Theaccidentcrewreportedfordutyonthedayoftheaccidentat0500attheDaytonaBeachInternationalAirport(DAB)inFloridaandflewtoATL,arrivingat0705.TheaccidentflightwasscheduledtodepartATLat0845,butwasdelayedduetominormaintenance.Theflightwasscheduledforaflighttimeofonehourandthirtyminutes,andtheweatherforecastatLGAforthetimeofarrivalwaswinds300degreesat12knots,visibilityone-halfstatutemilesinsnowandmist,withbrokencloudsat700feetabovegroundlevel(AGL).Whileenroute,theflightcrewobtainedAircraftCommunicationsAddressingandReportingSystem(ACARS)reportsofthecurrentLGAATISinformationandfieldconditionreportsforLGA.BoththecaptainandtheFOconsultedtheDeltaMD-88ODManddeterminedthat,basedonthecurrentandforecastedconditions,abrakingactionreport2of“good”wouldbeneededinordertolandsafelyatLGA.TheflightdepartedfromATLat0922.Thirty-threeminuteslater,thecrewrequestedandreceivedafieldconditionreport,whichstatedbrakingactionadvisories3wereineffect.Runwayswerereportedwetandsandedanddeicedwithsolidchemicals.

At1018,thecrewsentamessagetothedispatcheradvisingthattheywouldneedabrakingactionreportof“good”;anythinglesswouldmaketheflightunabletolandduetotherequiredlandingdistanceoftheaircraftattheexpectedlandingweight.Thedispatcherrepliedthathewouldpassalongabrakingactionreportoncehereceivedone.HestatedthatLGAwaslandingonRunway13atthetime.

Thecaptain,whowasthepilotflying(PF),briefedthathewouldflytheInstrumentLandingSystem(ILS)approachtoRunway13usingflaps40andmaximumautobrakesforlanding.AirTrafficControl(ATC)reportedthatbrakingactionwasreported“good”bybothanAirbusandaRegionalJet.At1050,thecrewreceivedanACARSmessagefromthedispatcheralsostatingthatthebrakingactionwas“good.”Withthatinformation,theflightcrewdecidedtherunwayconditionsweresuitableforlanding.

Thecaptainmonitoredthewindconditionsdisplayedonhisinstrumentsduringtheapproachandnotedthattheyhada10to11knotscrosswind,whichchangedintoaquarteringtailwindastheycontinued.Thetowercontrollerreportedthewindsas020degreesat10knotsjustpriortotheaircraftlanding.TheFO,whowasthepilotmonitoring(PM),calledout“approachminimums,”andthecaptainrespondedthathehadtherunwayinsight.Duringtheinterviews,bothpilotsstatedthattheysawtherunway

2AIMBRAKINGACTION—Areportofconditionsontheairportmovementareaprovidingapilotwithadegree/qualityofbrakingthathe/shemightexpect.Brakingactionisreportedintermsofgood,fair,poor,ornil.3AIM:BRAKINGACTIONADVISORIES—Whentowercontrollershavereceivedrunwaybrakingactionreportsthatincludetheterms“fair,”“poor,”or“nil,”orwheneverweatherconditionsareconducivetodeterioratingorrapidlychangingrunwaybrakingconditions,thetowerwillincludeontheATISbroadcastthestatement,“Brakingactionadvisoriesareineffect.”Duringthetimebrakingactionadvisoriesareineffect,ATCwillissuethelatestbrakingactionreportfortherunwayinusetoeacharrivinganddepartingaircraft.Pilotsshouldbepreparedfordeterioratingbrakingconditionsandshouldrequestcurrentrunwayconditioninformationifnotvolunteeredbycontrollers.Pilotsshouldalsobepreparedtoprovideadescriptiverunwayconditionreporttocontrollersafterlanding.


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centerlinelightsandthattherunwaywaswhiteandappearedcoveredinsnow.Theflightcrewstatedtheydidnotexpectasnow-coveredrunway.

Afterthecaptainhadtherunwayinsight,hestatedthatheadjustedhisaimpointtolandtheaircraftsoonerthanbriefed,butstillinthetouchdownzone.Theaircrafttoucheddownat1102,approximately600feetfromthethresholdandoncenterline,thecaptainloweredthenoseanddeployedthethrustreversers.Thecaptainstatedhewaslookingfora1.3EPRsettingand,therefore,movedtheleversoneknobwidth,whichiswhatthecaptainhaddeterminedtypicallyprovided1.3EPR.TheFOstatedthathefeltthatthespeedbrakesdidnotdeployautomatically,sohemanuallydeployedthem.Theaircraftdidnotexperiencethenormaldecelerationandbeganslidingtotheleft.Thecaptainstowedthethrustreversers.Theaircraftdidnotrespondtothecaptain’seffortstosteerthenosebacktotherightandultimatelydepartedtherunway.Afterslidingfurthertotheleftofftherunway,theleftwingimpactedtheairportperimeterfenceapproximately3,600feetdowntherunway.

TheFOshutdowntheenginesashewasconcernedthattheaircraftenginethrustwouldpushtheaircraftoverthebermandintoFlushingBay.Atabout4,500feetfromthethreshold,theaircraftseverelyyawedleft,andthenoseoftheaircraftbrokethroughthefenceontheberm.Theaircraftcametorestwiththecockpitstickingoutovertheberm.Theflightcrewstatedtheycouldseethedrop-offandthewaterbelowthem.FirefightersapproachedtheFO’spartiallyopenedwindowandadvisedthemtousetherightoverwingexit.Theleftoverwingexitwasnotutilizedbecausefuelwasspillingoutfromtheleftwing.Thecaptainorderedanevacuationthroughtherightoverwingexits.Thepassengersevacuatedthroughtherightoverwingexitandthroughthetailconeemergencyexit.

2.0 Operations

2.1 Weather

OnMarch5,2015,amajorwintersnowstormwasforecastedbytheNationalWeatherService(NWS).AbandofmoderatesnowwasexpectedoverNewYork,NewJersey,Maryland,andVirginia.ThecurrentATISthecrewreceivedwasinformationQuebecissuedat1551UTC,whichcorrespondsto1051.Thiswas12minutespriortotheaccident.Windswerereported030degreesat11knots,withavisibilityof0.25statutemileswithmoderatesnowandfreezingfogandaverticalvisibilityof900feet.Thetemperaturewas-3degreesCelsius(26degreesFahrenheit),thedewpointwas-5degreesCelsius(23degreesFahrenheit),andthealtimetersettingwas30.12inchesofmercury.TheATISstatedthattherunwayswerewet,sanded,anddeiced,buthad0.25inchesofsnow.Allrunwaysandtaxiwayshadthree-footsnowbanksontheedges.

LGAATISINFOQ1551Z.03011KT1/4SMSNFZFGVV009M03/M05A3012(THREEZEROONETWO).ILSRY13APCHINUSELNDRY13.DEPARTRY4.B4HOLDLINEINUSE.

BRAKINGACTIONADZYSAREINEFCT,NOBRKGACTIONADZYREPAVLBFORTFCDEPGRY31.TWYROMEORUNUPAREACLOSE.TWYWISKEYCLOSED.TWYYANKEEYANKEECLOSED.AIRMET


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SIERRAFORVISIBILITY.LGACLASSBSERVAVLBONFREQ12.ALLRUNWAYSANDTAXIWAYSHAVE3FOOTSNOWBANKSALONGTHEIREDGES.ALLTAXIWAYSAREWETANDHAVEBEENDEICEDWITHLIQUIDCHEMICAL.ALLRUNWAYSAREWETANDHAVEBEENSANDEDANDDEICEDWITHSOLIDCHEMICAL.ALLRWYFIELDCONDITIONS1/4INCHWETSNOBSERVEDAT1404Z.ALLTWYFIELDCONDITIONS1/2INCHWETSNOWOBSERVEDAT1404Z.RY4/22HAS,RWYHASBEEN,SANDED,CHEMICALLYTREATED.RY13/31HASBEEN,SANDED,CHEMICALLYTREATED.BIVOFLGAARPT....ADVSYOUHAVEINFOQ.

BasedonthewindsreportedbyTowerjustpriortolandingat11:00:32of020degreesat10knots,thetailwindcomponentwas4knots.AccordingtotheDeltaMD-88/90AircraftOperatingManual(AOM),themaximumtakeoffandlandingtailwindcomponentwas10knots.

TheofficialNWSMeteorologicalAerodromeReport(METAR)forthetimeoftheaccidentwasissuedat1551UTC(1051)winds010degreesat8knots,visibilityof0.25statutemilesandverticalvisibilityof900feet,withsnowandfreezingfog.

Therewassnowaccumulationof3inchesonthegroundfromtheprevioussnoweventandanadditionaltwoincheshadaccumulatedinthehourspriortotheaccident.Heavysnowwasreportedaftertheaccidentwithasnowfallrateof1inchperhour.Snowendedat1815withatotalof8inchesofnewsnowfall.

2.2 RegulationsforDispatchinganAircraft

Whileinthiseventtherewerenoissueswiththedispatchofthisaircraft,thisaccidentdididentifyanissuewithdispatchinganaircrafttoanairportthatmayhaverunwaycontaminationwhichmayprecludealanding.Whendispatchinganaircrafttoarunwaythatiswetorslipperyanadditional15%isaddedtothelandingdistance,inaccordancewith14CFR121.195(d).Anysnowaccumulationorbrakingconditionsarenotaddressedatthispointotherthantheadditional15percent.

SAFO06012,LandingPerformanceAssessmentsatTimeofArrival(Turbojets),whichwasissuedin2006,discussestheobligationofthepilottoperformlandingperformanceassessmentsbasedonactualconditionsonarrival.

Theflightcrewwasawareoftheseresponsibilitiesandwereactivelyinvolvedwithattemptingtogetreportsandupdatesforthearrivalairport,aswellasdetermineactiverunwayandthelandingrequirementsfromtheODM.Thisisreadilyapparentfromtheirinterviews,aswellastheACARScommunicationswithdispatch.

SAFO06012alsodiscussesbeingabletolegallydispatchanyaircraftwhentheaircraftmaynotbeabletolandbasedonavarietyofconditions,includingrunwaycontamination.Itstatesthat:

“Althoughanairplanecanbelegallydispatchedundertheseconditions,compliancewiththeserequirementsalonedoesnotensurethattheairplanecansafelylandwithinthedistanceavailableontherunwayactuallyusedforlandingintheconditionsthatexistatthetimeofarrival,particularlyifthe


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runway,runwaysurfacecondition,meteorologicalconditions,airplaneconfiguration,airplaneweight,oruseofairplanegrounddecelerationdevicesisdifferentthanthatusedinthepreflightcalculation.”4

Whenanaircraftisdispatched,14CFRPart121requiresoperatorstouseairportsthatareadequatefortheproposedoperation.Theserequirementslimittheallowabletakeoffweighttothatwhichwouldallowtheairplanetolandwithinaspecifiedpercentageofthelandingdistanceavailableon(1)themostfavorablerunwayatthedestinationairportunderstillairconditionsand(2)themostsuitablerunwayintheexpectedwindconditions.

Snowaccumulationorbrakingconditionisnotaddressed.Runwayconditionsshouldbeconsideredbythedispatcherpriortodispatch.Theflightcrewshouldnotbetheonlylineofdefensewhenevaluatingrunwayconditions.Ifawinterstormwithsignificantsnowfallratesisforecast,theairlineshouldberequiredtoconsiderthisinformationandtheimpactitwillhaveonbrakingactionpriortodispatch.

2.3 CrewExpectationofRunwayCondition

WiththeinformationthecrewhadreceivedfromthedispatchreleaseandfromtheATIS,currentatthetimeoftheapproach,thecrewwasexpectingaclearedrunwaythatwaschemicallytreated.At300feet,whentheaircraftbrokeoutoftheclouds,thecaptainwasabletoidentifytherunwayandhewasabletoseetherunwaycenterlinelightsandtherunwayedgelights,buttherunwaydidnotlooklikewhathewasexpecting.Basedontheinformationreceived,heexpectedtobeabletoseesomepartoftherunway,buttherunwaywasallwhite.5TheFOhadaverysimilarpictureinmind,andhewasexpectingawet,sanded,andchemicallytreatedrunway.Hefeltthathewouldhavebeenabletoseetherunway,itsassociatedmarkings,andperhapssomeslush,butnotalayerofsnow.Whenthecaptaincalledoutthathehadtheapproachlightsinsight,theFOlookedupandsawtheapproachlightsbutnottherunway.6Thecaptainadjustedhisaimpointtolandwithinthefirst1,000feetandtostoptheaircraftasquicklyaspossible.7

Theinformationtheflightcrewreceivedledthecrewtoexpectacleared,mostlybaresurface,insteadtheysawonlyrunwaylightswiththesurfacecoveredinsnow.Thisincreasedthecrew’sconcernoverthequalityoftherunwayconditions.However,thecrewhadreceivedtwogoodbrakingactionreportsfromLGATowerwithpilotreports(PIREP)issuedbyaprecedingAirbusandaRegionalJet,andthecrewelectedtocontinuetheapproachandlanding.

2.4 Approach

Basedontheflightdatarecorder(FDR),airportsurveillanceradar(ASR)andsurfacemovementradar(SMR)data,8theaircraftflewastableapproachperDelta’soperationalpolicies.

4SAFO06012,issuedAugust31,20065OperationsGroupFactualReport—Attachment1—InterviewSummaries,page166OperationsGroupFactualReport—Attachment1—InterviewSummaries,page47OperationsGroupFactualReport—Attachment1—InterviewSummaries,page168PerformanceStudy,page8


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Figure1:DeltaMD-88/90OperationsManual—NormalProcedures,StabilizedApproach

Theaircrafttouchdownpointwascalculatedas600feetfromtherunwaythresholdataspeedof133knots,whichisconsistentwiththecalculatedVref131knots+5knots.Thenosewheelstoucheddownapproximately1,200feetfromthethreshold.9Themagneticheadingoftheaircraftupontouchdownwasapproximately132degreeswithamagneticrunwayheadingof134degrees.

2.5 LandingDistanceAssessment

TheDeltaAOMguidanceforlandingoncontaminatedrunwaysincludedseveralitemsapplicabletothisflight,andtheflightcrewfollowedthisguidance.TheAOMrecommendedtheuseofmaximumlandingflapconfigurationandtheuseofmaximumautobrake.Furthermore,itstateditisadvisabletolandasearlyinthetouchdownzoneaspossibleandcalledformaximumallowablereversethrust.Ifsideslippingontherunway,reverseistobeselectedatidle,andthebrakesshouldbereleasedinordertoreturntothecenterline.Theflightcrewfollowedallofthisguidance.Theaircraftwasconfiguredwithflaps40andmaximumautobrakeselected.AccordingtotheDeltaODM“quickreferencechart—operationallandingdistances”thelandingdistancefortheMD-88configuredwithflaps40degrees,weighing127,500pounds,andusingthemaximumautobrakeselectiononarunwaywith“good”

9PerformanceStudy,page48


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brakingactionwas6,050feet.10Thelandingdistanceforthesameconfigurationandrunwayconditionbutusingmaximummanualbrakingwas5,350ft.

Landingwiththesameconfiguration,butwithabrakingactionoflessthan“good,”theODMstatedalandingdistanceof7,700feetutilizingmaximumautobrakesettingand7,150feetusingmaximummanualbrakingfor“medium”brakingaction.BothofthesedistanceswouldexceedtherunwaylengthatLGAof7,003feet,andthisflightwouldnothavebeenabletolandwithanyreportedbrakingactionoflessthan“good.”

Theaircrafttoucheddownapproximately600feetfromthethreshold.Duetothecontaminatedandshortrunway,thecrewunderstoodtheneedtomaximizetheavailablerunwaydistanceforbraking.

2.6 RunwayConditiononthePier

Figure2:Delta10-7Page,CautionforLandingsonLGAPier

Runway13atLGAis7,003feetlong.Thefirst1,000feetisconstructedofaconcretepier.Coldaircirculatesunderthepiercausingthesurfacesonthepiertofreezebeforethesurfacesoftherestoftheairportincoldweatherconditions.

TheLGARunway13surfacetemperaturemeasuredatasensormountedintherunwayonthepierwas32.2degreesFahrenheit.Thistemperaturewasconstantfrom0751to1651,whiletheairtemperatureduringthesameperiodoftimedroppedfrom31.6degreesto24.5degrees.Duringtheperiodfrom0851toaftertheaccidentoccurred,freezingfogwasreportedintheLGAATIS.Thesefogdropletsfreezeuponcontactwithexposedobjectsandformacoatingofrimeand/orglaze.11Withairtemperaturebelowfreezing,waterdropletsinfogcanbecomesupercooled.Inthisform,supercooledliquiddropletsfreezewhenincontactwithanobject.

Theconstantrunwaysurfacetemperatureisconsistentwithsupercoolliquiddropletsreleasinglatentheatduringtheprocessoffreezingtothepier.Thiskeepsthepierataconstantsurfacetemperaturemeasuredat32.2degreesFahrenheit12whileaccumulatingice.

10Landingdistanceisbasedonthelandingweightfoundinthespeedcardinthecockpit.OperationsGroupFactualReport—Attachment411NationalWeatherServiceGlossary12AirportsGroupFactualReport—Attachment1—SnowLogPages3–5


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2.7 MD-88SpoilerSystem

TheMD-88hasspoilerpanelsoneachwingthatareusedtoreduceliftandinducedrag.Thetwooutboardpanelsoneachwingfunctionasflightspoilers.Theyextendforrollaugmentationinflight.Theyassisttheaileronsinprovidingarollmomentwhenthecontrolwheelisrotatedpastacertainposition.Theyalsoprovideaspeedbrakefunctionbycreatingdragwhendeployedbythespeedbrakehandle.Whenusedtogether,thesetwocontrolinputsareresolvedthroughthespoilermixercontrol,whichvariestheextensionofspoilersonthewingsbasedoninputsfromthesecontrolinputs.

Thesepanelsalsoinduceadditionaldragandspoilliftwhenextendedtothegroundextensionposition.Thisiscontrolledbythespeedbrakehandleandprotectedfromdeploymentinflightbyguardsinthespeedbrakehandletrack,aswellasdevicesinthespeedbrakehandlecontrolsystem.Toaugmentthisfunctionduringlandingrollout,twoadditionalspoilerpanelsattheinboardsectionofthewingarededicatedtogroundspoilerdeployment.Thesetwoinboardgroundspoilersrequirespeedbrakehandlemovementtothegroundextensionpositionandwheelspin-updetectionthroughthewheelspeedtransducerstodeploy.Inabsenceofwheelspin-up,nosegearWOWcompletesthecircuittoextendthegroundspoilerpanels.

Whenarmed,theMD-88autospoilersystemprovidestimelyactivationofspoilersattouchdownwithoutpilotaction.Autospoilerarmingispreselectedduringtheapproachbymovingthespeedbrakehandletothearmedposition.Ontouchdown,thespeedbrakehandleismovedtothegroundextensionpositionbyanactuator.Inordertoauto-deploythespoilers,thesystemneedsinputfromeithermainwheelspin-upornosewheelWOW.Iftheseinputparametersarenotprovidedtothesystem,theactuatorwillnotdeploy,andthespeedbrakehandlewillnotautomaticallymovetotheextendposition.Ifautomaticdeploymentdoesnotoccur,thepilotsmustmanuallydeploythespoilersbymovingthespeedbrakehandletothegroundextensionposition.

Duringtheflare,theindicatedairspeedbegantoreduce,andabouttwosecondslaterat11:02:16averticalspikeorincreaseinverticalaccelerationoccurs.Thisspikeisconsistentwiththeaircrafttouchingdownontherunway.Theaccelerationdecreasestolessthan1.0Gandasecondverticalspikeofabout1.3Gs,slightlyfirmerthanthefirst.13Thistroughbetweenspikesindicatesareboundfromstrutcompression.Theaccelerationwaslessthan1.0Gforabout1.4seconds.Thisisnotsufficientfortheaircrafttobecomeairborne.Thepilotsreportedanormalandfirmtouchdown.TheverticalaccelerationrecordedisconsistentwithotherlandingsofMD-88s,includingtheprecedingDeltaflightlandingatLGA.14

Groundspoilersconsistofthreespoilerpanelsoneachwing.Twooutboardpanelsalsofunctionasflightspoilers.Theyareusedforrollaugmentationinflight.Theyassisttheaileronsinprovidingarollmomentwhenthecontrolwheelisrotatedpastacertainposition.Theyalsoprovideaspeedbrakefunctionbycreatingdragwhendeployedbythespeedbrakehandle.Whenusedtogether,thesecontrolsare

13FDRGroupFactualReport,page514FDRGroupFactualReport—Attachment1,page5


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resolvedthroughthespoilermixercontrol,whichvariestheextensionofspoilersonthewingsbasedoninputsfromthesecontrols.

Thesepanelsalsoinducedragandspoilliftwhenextendedpastnormalrollextensiontogroundextensionposition.Thisiscontrolledbythespeedbrakehandleandprotectedfromdeploymentinflightbyguardsinthespeedbrakehandletrack,aswellasdevicesinthespeedbrakehandlecontrolsystem.Toaugmentliftdissipationduringlandingrollout,twospoilerpanelsattheinboardsectionofthewingarededicatedtogroundspoilerdeployment.Thesespoilersrequirespeedbrakehandlemovementtothegroundextensionpositionandwheelspin-updetectionthroughthewheelspeedtransducerstodeploy.Incaseoflossofwheelspin-up,nosegearshiftdetectioncompletesthecircuittoextendthegroundspoilerpanels.

Spoilerextensionisrecordedat1hertz(Hz)(oncepersecond)whileverticalaccelerationismeasuredat8Hz.Theleftoutboardandrightinboardspoilerpositionincreasesfrom0to60degrees,whichisfullgroundextensionbetween11:02:17and11:02:19,andtheverticalaccelerationpeaksat11:02:18,consistentwithmovementofthespeedbrakehandletothefullaft,groundspoilercommandposition.TheFDRdataisconsistentwiththeFO’saccountthathedidnotbelievethatthespoilersauto-deployedandmovedthespeedbrakehandletomanuallydeploythem.Verticalaccelerationagainshowsasmalldipandsmallerpeakat11:02:20EST.

2.8 MD-88AutoBrakeSystem

Theautobrakesystem(ABS)providesreliableautomaticsymmetricbrakingtoensureconsistentdecelerationonlandingroll.Theautobrakesystemispreselectedtoprovideappropriatebrakingschedules.TheABSmodulatesbrakepressuretocontrolbrakeapplication.

Figure3:DeltaMD-88/90OperationsManual,AutoBrakeControlPanel


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Figure4:DeltaMD-88/90OperationsManual,AutoBrakeSelectorandDecelerationRates

ABSscheduleisselectedontheABSpanelbyrotatingtheautobrakeselector.ItisthenarmedforoperationbyplacingtheABSswitchintheARMEDposition.Theautobrakesystemactivateswhenthespeedbrakehandleismovedtothefullaftpositionduringtouchdown.

ThecrewofthisflightselectedLANDMAX.DeltaMD-88/90OperationsManual,ContaminatedRunway,Landing,SP16.14containsthefollowingguidance:

“ConsiderusingMAXautobrakesformaximumstoppingeffectiveness.”

Selecting“LANDMAX”wouldprovidefullbrakesystempressuretotherightbrakepressuremanifold.Inmostlandingsituations,brakingratewouldbethemaximumavailableandlimitedonlybymodulationoftheantiskidsystem.

TheautobrakesintheMAXpositionhasa1seconddelaytoactivation.15

2.9 Antiskid

TheMD-88hasantiskidprotectionformainwheelbraking.Theantiskidsystemcomparesrotationspeedbetweenwheelsduringbrakingingroundoperations.Itthenmakesadeterminationifatireisapproachingaskidandmodulatesbrakepressuretothatwheel.Theantiskidsystemrequireswheelrotationaboveacertainspeedtooperate.16

2.10 AircraftPerformanceAfterTouchdown

Theaircrafttoucheddownabout600feetfromthebeginningofthetouchdownzone.Thiswouldplaceitinaboutthecenteroftherunwaypiersection,whichextendsoverFlushingBay.Becauseoficeaccumulationduetofreezingfogandsnow,thesurfaceofthepierwouldbeicy.Ontouchdown,theFOnoticedthattheautospoilersdidnotactivate.

TheFOstatedthatitfelttohimthespoilerstooktoolongtodeploy.Hewaitedasecondlongerthannormalandthenmanuallydeployedthespoilers.17ThisisinaccordancewiththeDALFCTM,which

15DeltaOperationsManual,Vol2,page14.20.716DeltaFCTM,page6.19:“Whenbrakesareappliedonaslipperyrunway,severalskidcyclesoccurbeforetheantiskidsystemestablishestherightamountofbrakepressureforthemosteffectivebraking.”17OperationsGroupFactualReport—Attachment1—Interviewsummaries,page4


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statesthattheaircraftshouldbeflownfirmlyontotherunwayattheaimingpoint.Avoidholdingtheaircraftofftheground.Bepreparedtomanuallydeployspoilers,ifautomaticdeploymentdoesnotoccur,aswheelspin-upmaybedelayed.18

Atthispoint,threeauralindicationsofacautionfromtheCAWSarerecordedontheCVRincluding“spoilers.”TheCAWSspoilerscautionisannunciatedwhenflapsareinthelandingposition,thespeedbrakehandleisnotintheretractedposition,andtheaircraftisinflight.TheFDRrecordsmovementoftheleftoutboardandrightinboardflightspoilerpanels.Theleftoutboardspoilerfirstrecordedmotionat11:02:17.5(1.5secondsaftermaingeartouchdown),andbothspoilersshowedfulldeploymentsoonafter.Thetwoinboardgroundspoilerpanelsrequireinputfromtheproximityswitchelectronicsunit(PSEU)toextend.ThePSEUuseswheelspin-upornosestrutcompressioninputstodeterminegroundstatus.Therefore,thegroundspoilerpanelswouldhavedeployedatnosewheeltouchdown,recordedat1102:19.TheCAWS“spoilers”cautionceasesatthispoint,aswell.

Brakingactionisafunctionofdownforceonthebrakingwheels(main)andthesurfacefriction.Thefailureofthespoilerstoautodeploywasmostlikelythefailureofthemainwheelstogetsufficienttractionontheicysurfaceofthepiersection.Thesubsequentdelayinspoileractivationandthefurtherdelayingroundspoilermovementwouldhavecausedaperiodaftertouchdownofreduceddownforce.Duringthistime,speedbrakehandlemovementtothedeployedpositionbytheFOwouldhavecausedmaximumautobrakeactivationaftera1seconddelay.Ifwheelsweresubjecttobrakepressurebeforeadequaterotationspeed,theywouldlockquickly.Lockedwheelswouldnotprovideusefulbrakingorcorneringforce.Thewheelswouldstaylockedunlessrotationandantiskidwereregained.Inthecaseofallfourwheelsbeinglocked,thiswouldrequireacompletereleaseofthebrakesandthenreapplication.DuringtestimonyfortheAmericanAirlines(AA)Flight1420accidentpublichearing,aNASAengineerstatedthatabnormalantiskidoperationwouldbeexpectedwithlowtonowheelspin-upaccelerationsonalowtonotractionrunwaysurfaceanddelayedspoilerdeployment.

TheFOstatedthathedidnotfeelanyactionfromtheautobrakesandthathecouldfeelthespoilersandthethrustreversetakeeffect,butnotthewheelbrakes.19Allthreeflightattendantsstatedthattheaircraftdidnotdeceleratedasexpected.20Thestatementsindicatethattheydidnotfeelthesuddenbrakingonsetusuallyassociatedwithlandings.

Astheaircraftcontinueddowntherunway,theelevators’nose-downdeflectionincreased.Thiswouldhavefurtherreduceddownforceonthemaingearandshiftedweighttothenosegear.Addedweighttothenosegearwouldhavealsoincreaseditscorneringforce.Theaircraftbegantorotatewiththenosemovingleftandthetailmovingright.Themaingearremainedneartherunwaycenter.Theaircraftdidnotresistthisforceinanydiscernableway,indicatinglittleornocorneringforce.

18DeltaFCTM—Section6.15—Landingonwetorslipperyrunways19OperationsGroupFactualReport—Attachment1—Interviewsummaries,page420SurvivalFactors—Attachment4—Interviewsummaries


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Figure5:PassengerPhotographoutoftheleftsidewindowatthe500footrunwaymarker.Noteretractedspoilerpanels.

2.11 ThrustReversers

Thethrustreversersredirectthethrustinapproximatelya45-degreeangleaboveandbelowtheenginefromthedirectionofforwardthrust.Thisprovidesadditionalstoppingcapabilitiesinadditiontothewheelbraking,enablingshorterlandingrolloutdistances.

TheBoeingFlightOperationsissuedabulletindatedNovember5,2002,toalloperatorsofMD-80seriesaircraftinresponsetoanNTSBrecommendationconcerninguseofreversethrustunderwetorslipperyrunwayconditions.Thisbulletincautionsthat1.3enginepressureratio(EPR)shouldbeusedasthemaximumreversethrustpowerunderwetorslipperyrunwayconditions.SimilarguidancewasincludedintheAllOperatorLetter(AOL)fromFebruary15,1996,thatstatesthatreverseEPRofabove1.3EPRcanresultinrudderblankingreducingthedirectionalcontrol.

Boeingprovidedthisinformationtooperators(airlines)asoperationalguidance.Theoperatorsthenmodifiedtheirmanualsandproceduresasnecessary.DeltaFCTM6.22includedthisnote:

“Note:(88)Normaldryrunwayreversethrustminimumis1.3EPR,target1.6EPR.”


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DALMD-88/90OperationsManualSP.16.10includedthisstatement:

“CAUTION:Reversethrustabove1.3EPRmayblanktherudderanddegradedirectionalcontroleffectiveness.However,aslongastheaircraftisalignedwithrunwaytrack,reversethrustmaybeusedasnecessary(uptomaximum),tostoptheaircraft.”

Delta’smanualsdidaddressthelossofrudderandsubsequentlossofdirectionalcontrolduetoEPRgreaterthan1.3inthecautionstatementabove.Thisstatementbeginsthesectiontitled“LandingonWetorSlipperyRunways”However,thisstatementisnotdirectlyspecificguidanceforslipperyorwetrunwayoperation.Furtherthiswarningwasmadeambiguouswiththeadditionalstatementthatuptomaximumreversethrustmaybeused,asnecessary,aslongastheaircraftisalignedwiththerunway.ThissamesectionoftheFCTMdiscussesreverseEPRapplication:

Onwet,contaminated,orslipperyrunways,immediatelyafternosegeartouchdown,maximizeanti-skidbrakingoperationbyapplyingfullbrakepressuresmoothlyandsymmetricallywhileapplyingreversethrusttotheidlereversedetent.Afterreversethrustsymmetryisverified,graduallyincreasereversethrustasrequired.Reversethrustshouldbeappliedsmoothlyandsymmetricallyto1.3EPRassoonaspossiblesincethereversethrusteffectivenessisgreatestathigherspeeds.

Although1.3EPRisagainmentionedhere,itisnotdefinedaseithertargetorlimit.Noristhereanyadditionalreferencetorelatetocontroldifficulties.

AsDeltaflight1086exceededthe1.6EPRtarget,theaircraftbegantoyawleft.Within1.5secondsoftheleftyawmoment,thethrustwasreducedfromthemaximumandthereverserswerefullystowedwithin4seconds.Atthistimetheaircraftwasapproximately5feettotheleftoftherunwaycenterline.

ThemaximumEPRsettingontheaccidentflightduringtheuseofreversethrustwas2.09ontheleftengineand1.9ontherightengine.HigherthanBoeing-recommendedreversethrustEPRsettingsarenotuncommonforDeltaaircraftdataexaminedinthisaccident.TheNTSBexaminedquickaccessrecorder(QAR)datafrom59previouslandingsofthisaircraft.Onhalfoftheselandings,anEPRsettingabove1.6formorethan4secondswasrecorded.Thisincluded6otherlandingsoncontaminatedrunways.TheprecedingDeltaAirlinesMD-88aircraftlandingatLGArecordedEPRvaluesreaching1.8ontheleftengineand1.5ontherightengine.Thisaircraftreportednolandingdifficulties.MD-80Seriesaircraftdatafromotherairlineswasnotexaminedduringthisaccident.

2.12 ManualBraking

Asthethrustreverserswerestowedat11:02:24.5,thebrakepressureintheleftsystemwasrecordedat3000PSI.Shortlythereafter,thepressureintheleftsystemdropped,andanincreaseintherightbrakesystemwasrecorded.Thisisconsistentwiththeapplicationofmanualbrakes.Thecaptainappliedrightdifferentialbrakepressurewhichwouldcorrespondtoactiontocorrecttheleftyawthattheaircraftwasexperiencingatthattime.Applicationofmanualbrakingbydepressingbrakepedalswilldisarmtheautobrakesystem.


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2.13 UseofRudder

Rightrudderinputwasfirstrecordedat11:02:20.5andincreasedoverthenext4secondstoavalueofabout12degrees.DuringthistimethethrustreverseEPRsettingwasinexcessof1.6,andtherudderhaslostmostofitseffectiveness.Therudderdeflectionrevertedbacktoalmostzerowithinthenextsecond,andataroundthesametimethethrustreverserswerestowed.Anothersecondlater,rightrudderdeflectionwasapproachingthemaximumrecordedvalueof21degrees.Therudderhadregainedeffectivenessatthistimeasthethrustreversershadbeenstowed.Themaximumdeflectionof21degreeswasreachedat11:02:26,twosecondsafterthethrustreversershadbeenstowed.Atthispoint,theheadingdidnotincreaseanymore.

2.14 Control-ColumnPositionvs.ElevatorPosition

Theelevatorsarepoweredaerodynamicallybymovementofacontroltabonthetrailingedgeofeachelevator.Thiscontroltabismovedbycablesattachedtothecontrolcolumn.Asthecontrolcolumnismovedforwardtoaft,thecontroltabmovesfromuptodown.Thiscreatesanaerodynamicforcethatdrivestheelevatorfromdowntoup.Theactualelevatorpositionistheresultofallaerodynamicforcesontheelevatorandmayvaryfromspecificcontrol-columnpositionindifferentaircraftconfigurationsandflightconditions.

TheFDRrecordedtheelevatorsataflightpositionaround2degreesnosedown(-2)movingtoapositionaround-15degreesaftertouchdown.Atthesametime,thecontrolcolumnmovedfromaround10degreesnoseuptoaround5degreesorlessnosedown.Themaximumparameterforelevatortravelis15degrees(displayedasminus)trailingedgedown,andforcontrolcolumnis10degrees(displayedasminus)forward.

Thisplacedtheelevatorsatornearthemaximumfull-downpositionformostofthegroundrollfromgroundshift(WOW)leadingthroughlossofheadingcontrol.Theelevatorsreached15degreesnosedownonesecondbeforetheheadingbegantomoveleftandvariedbetween15and12degrees.


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Figure6:ElevatorandControl-ColumnPositionAfterNose-GearTouchdown

Theelevatorsdorespondandfollowdirectionofcontrol-columnmovementduringthisperiod.Buttheirmovementappearsoutofproportiontodisplacementofcontrol-columnmovementtowardnosedown.Forexample,thecontrolcolumnremainedwithin1degreeof4degreesofnose-downcolumnposition,abouthalfofitsforwardtravel,formostofthefirst10seconds.However,theelevatorsremainedbetween11and15degrees;twothirdstofulltravel.Theleftelevatorshowedgreatertravelthantheright.TheleftreverseEPRwasalsohigherthantherightduringthisperiod.Theeffectseemssomewhatdiminishedwhenreversersstowed.

ComparingtheFDRdatafromthepreviousMD-88,theelevatordisplacementwasmoreinproportiontocontrol-columnpositionduringthesameperiodaftertouchdown.However,theleftEPRreached1.7duringinitialapplicationofreverse.Theleftelevatorexceeded10degreesandreached12degreesnosedownwithcontrolwheelnotexceeding5degrees.Duringthissameperiod,therightEPRremainedcloserto1.3andpeaksat1.5.

Thissuggestsanincreaseinelevatorsensitivitytowardtrailing-edgedownduringreversethrust,mostnoticeableaboveabout1.5EPR,inthesetwoflights.

2.15 LiftingForcesontheRearSection

Theelevatortrailingedgeinadownpositioncausesanose-downattitudebycreatingliftonthetail.Ontheground,thiswilllifttherearsectionoftheaircraftand,therefore,decreasethedownwardforceonthemainlandinggear.Anylossindownforcereducestheabilityofthetirestoproducebrakingandcorneringforces.Thishasanegativeimpactonthealreadydecreasedbrakingactiononthecontaminatedrunway.TheDeltaFCTMstatesto“avoidexcessiveforwardcontrol-columnpressurein

-11.8

-15.35-13.54

-12.02-12.87 -12.65

-14.51-13.08

-12.07

-3.88

-4.46

-4.43

-4.76-4.7

-4.23

-3.89

-3.57

-3.11-2.32

-5.09-5.45

-3.59-1.71

-1.38-1.1

-14.61 -15.35 -15.5 -14.46

-13.18

-15.5

-11.64-8.9

-16

-14

-12

-10

-8

-6

-4

-2

01 4 7 10131619222528313437404346495255586164

Elevator&ColumnAfterTouchdown

LElevator

Cont.Column

RElevator


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ordertomaintainmaximumbrakingeffectivenessandtoreducepossibilityofnosewheelspray.”21Pilotsholdingcontrolcolumnjustforwardofthecenterpositionwouldnotexpecttobecausingexcessiveelevatormovement.

Additionally,thethrustreversersexhaustgasisdeflectedata45degreeanglefromthedirectionofthrustaboveandbelowtheengine.22Thiseffluxpatternwillhaveaverysimilarimpactastheelevatortrainingedgeinadownpositionandcausesanupwardforceontherearsectionoftheaircraftandreducingthedownforceonthemainlandinggear.

TheflightcrewfollowedguidancefromtheFCTMonbraking,pitch,anduseofreversethrust.

2.16 DiscrepanciesinManualsandGuidance

2.16.1 UseofCautionandWarning

TheAOMreferencedcautionandWarningstatementstoemphasizepotentialhazardousconditions.Severalstatementslabeledas“caution”betterdescribeinstructionsthatmeetthedefinitionaswarningsinaccordancewiththeDeltaOperationsManualVol1–P1.2.4.Thiscouldaffectthepilot’sinterpretationofthethreatnotedinthesestatements.

Figure7:MD-88/90OperationsManualVol1—PageP1.2.4,definitions

Inthefollowingexample,the“CAUTION””shouldbea“WARNING”becausethepotentiallossofcontrolcanleadtoinjuryorlossoflifebasedontheinformationfromFigure7above.

21FCTMSection6.16—Landingonslipperyrunway22AirworthinessGroupFactualReport—Addendum1,page3


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“CAUTION:Reversethrustabove1.3EPRmayblanktherudderanddegradedirectionalcontroleffectiveness...”23

“CAUTION”and“WARNING”statementsthroughoutthemanualandshouldbevalidated.

2.16.2 EPRLimitation

Boeingguidanceof1.3EPRmaximumfortheuseofreversethrustisdescribedasa“limit.”24GuidanceintheDeltamanualswasdifferent,asstatedintheFCTM,whichstatesthefollowing:“CAUTION:Reversethrustabove1.3EPRmayblanktherudderanddegradedirectionalcontroleffectiveness.However,aslongastheaircraftisalignedwithrunwaytrack,reversethrustmaybeusedasnecessary(uptomaximum),tostoptheaircraft.Donotattempttomaintaindirectionalcontrolbyusingasymmetricreversethrust.”25AnewsletterfromApril2014includedreferencetoEPRtargetvalues:“Reversers:LineCheckdatashowsthatmanypilotsacceptreversersettingsfarbelowthetarget.RememberontheMD-88,foradryrunwaytheMINIMUMis1.3EPRandtheTARGETis1.6.Onarunwaythatisnotdry,1.3EPRisthetarget.”26

DeltamanualscalledouttargetsforEPRsettingsasopposedtolimitscalledforbyBoeing.DeltaguidancealsoallowedfortheuseofEPRsettinginexcessof1.3,uptothemaximum,oncontaminatedrunwaysaslongatdirectionalcontrolismaintained.

2.16.3 ThrustReverseDeploymentandEngineAcceleration

Practicalexperienceshowsthatduetovariationinthrustreverserrigging,engineconfigurations,bleedairconfigurations,andengineidle,largevariationsinEPRsettingsandengineaccelerationduringapplicationofreversethrustmayoccur.Thisvariationoccursacrossthefleetandevenbetweenenginesmountedonthesameaircraft.27Thisresultsinasplitbetweenleftandrightenginethrust,whichinducesayawmomentandcomplicatesestablishingaspecifictargetEPR.Reversethrustismosteffectiveathighairspeed;therefore,establishingappropriatereversethrustquicklyaftertouchdownresultsinthemostefficientdeceleration.

TheFCTMemphasizedearlyestablishmentofreversethrust.

“Reversethrustshouldbeappliedsmoothlyandsymmetricallyto1.3EPRassoonaspossiblesincethereversethrusteffectivenessisgreatestathigherspeeds.”28

23DeltaMD-88/90FlightCrewTrainingManual—Landing6.1524OperationsGroupFactualReport—Attachment19—BoeingAllOperatorLetterAOL-9-05825DeltaMD-88/90FlightCrewTrainingManual—Landing6.1526OperationsGroupFactualReport,page2827PerformanceStudy,page4228DeltaFCTM,page6.15-17


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“Theimportanceofestablishingthedesiredreversethrustlevelassoonaspossibleaftertouchdowncannotbeoveremphasized.Thisminimizesbraketemperaturesandtireandbrakewear,andreducesstoppingdistanceonveryslipperyrunways.”29

“Note:Reversethrustandspoilerdragaremosteffectiveduringthehigh-speedportionofthelanding.Deploythespeedbrakeleverandactivatereversethrustwithaslittletimedelayaspossible.”30

“Note:Spoilersfullydeployed,inconjunctionwithmaximumreversethrustandmaximummanualantiskidbrakingprovidestheminimumstoppingdistance.”31

However,theimportanceofcarefullyestablishingaccurateandsymmetricalreversethrustisreflectedinfleetpublications:

Boeingstatesthefollowing:

“Applyreversethrusttoidlereversethrustdetent.Afterreversethrustisverified,graduallyincreasereversethrustasrequiredtonomorethan1.3EPR.”32

DeltaFCTMstates:“Afterreversethrustsymmetryisverified,graduallyincreasethrustasrequired.”33

“MD-88Reversers:Onthe88strivetoattain1.6EPR(N1’sat1o’clock)andbepatient;itwilldecelerate.Giveitafewsecondsbeforejumpingonthebrakes.1.6iseasiesttoattainifyou“walk”thereverselevers2knobwidthsfromidle.Astheengineswindupallittakesisabumpforeoraftasyouseewhichsideisincreasingfastorslow.Don’tkeeppulling,letithavetimetoreact.Practicethisonthelongrunwayssothatyoucanreliablygetthereontheshortrunways”34

GuidanceintheDeltamanualsatthetimeoftheaccidentrecommendedtoestablishreversethrustassoonaspossible,asreversethrustismosteffectiveinhighairspeed.TheFCTMandBoeingguidancebothincludedguidancethatsuggeststhatsymmetricalreversethrustshouldbeverifiedandthengraduallyincreased.Thisiscontradictingguidance,asitisimpossibletoestablishdesiredreversethrustassoonaspossibleandatthesametimeverifysymmetryandgraduallyincreasereversethrust.

2.16.4 Control-ColumnUsage

GuidanceprovidedbybothDeltamanualsandBoeingdiscussedtheneedofforwardcontrol-columnpressureinordertoaiddirectionalcontrol.Increasedforwardpressureincreasesweightonthenosewheelandprovidesimprovednose-wheelsteering.Inthesameguidance,however,Boeingstatedthattheuseoftoomuchforwardpressureasthismayunloadthemaingearandcausereducedbrakingaction.Reducedbrakingactionwilldelayauto-spoilerdeployment.

29DeltaFCTM,page6.1830DeltaFCTM,page6.1431DeltaFCTM,page6.1432OperationsGroupFactualReport—Attachment19—BoeingAllOperatorLetterAOL-9-05833DeltaFCTM,page6.1634OperationsGroupFactualReport,page28


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DeltaFCTMstated:“Ontouchdown,takepositiveactiontolowerthenosewheeltotherunwayandmaintainmoderateforwardpressureoncontrolcolumntoassistindirectionalcontrol.Avoidexcessiveforwardcontrol-columnpressureinordertoretainmaximumbrakingeffectivenessandtoreducepossibilityofnosewheelspray.HydroplaningmaycausedelayedAutoSpoilerdeployment.”35

FCTM:“Slightforwardpressureonthecontrolcolumnmaybeneededtoachievetouchdownatthedesiredpointandtolowerthenosewheelstotherunway.Afterloweringthenosewheelstotherunway,holdlightforwardcontrol-columnpressureandexpeditiouslyaccomplishthelandingrollprocedure.Fullreversethrustisneededforalongerperiodoftime.”36

FTCM:“Ontouchdown,takepositiveactiontolowerthenosewheeltotherunwayandmaintainmoderateforwardpressureoncontrolcolumntoassistindirectionalcontrol.”37

BoeingAllOperatorLetterstated:“Whenoperatingonwetorslipperyrunways,applysufficientdownelevatorafternosegearcontacttoincreaseweightonthenosewheelforimprovedsteeringeffectiveness,butnotanexcessiveamountwhichwillunloadthemaingearandreducebrakingefficiency”38

Thesestatementsillustratethechallengespresentedtothepilotsbetweeninsufficientnose-wheelsteeringandlossofbrakeeffectivenessandcorneringforceofthemaingear.Althoughtheimportanceofcorrectcontrol-columnpositionisemphasized,noobjectiveguidancetoachievethisisprovided.

2.16.5 DirectionalControlLossonSlipperyRunways

DeltaAirLinesmanualsofferedguidanceforlandingonslipperyrunwaysforflightcrewstoconsider.Thisincludedguidanceaboutthetouchdownzoneandtheuseofthethrustreverseranddirectionalcontrol.

TheBoeingAOLgaveguidanceforregainingdirectionalcontroliflostonaslipperyrunwayduringuseofreversethrust.Deltamanualsalsorecognizedthisthreatandgaveguidance.However,inbothcasestheguidancevariedaspublishedandmaycauseunresolvedconflictsforpilotstryingtorespondtoaskid.

BoeingAOL9-058,1996:“Ifdifficultyinmaintainingdirectionalcontrolisexperiencedduringreversethrustoperation,reducethrustasrequiredandselectforwardidleifnecessarytomaintainorregaincontrol.Donotattempttomaintaindirectionalcontrolbyusingasymmetricreversethrust.”

BoeingFOB80-02-03“reiteratesinformationcurrentlyincorporatedintheBoeingMD-80FlightCrewOperatingManual.”Theguidanceforregainingdirectionalcontrolisvirtuallyunchanged.However,thebulletinincludesthestatementthatcrewsidentifyreverse-thrustEPRtargetsduringapproachbriefings.Italsoadvises:“Afterthrust-reverserdeploymentonrollout,thePilot-Not-Flying(PNF)dutiesshould

35DeltaFCTM,page6.1636DeltaFCTM,page8.1837DeltaFCTM,page6.1638OperationsGroupFactualReport—Attachment19—BoeingAllOperatorLetterAOL-9-058


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includemonitoringreverse-thrustdeploymentandadvisingthePilot-Flying(PF)ofexcessiveEPRsettingsshouldtheyoccur.”

DeltaFCTMhadasectionlabeled“LandingonWetorSlipperyRunways,”whichstatedthefollowingregardingskid:

“Ifaskiddevelops,especiallyincrosswindconditions,reversethrustwillincreasethesidewardmovementoftheairplane.Inthiscase,releasebrakepressureandreducereversethrusttoreverseidle,andifnecessary,toforwardidle.Applyrudderasnecessarytorealigntheairplanewiththerunwayandreapplybrakingandreversingtocompletethelandingroll.Itisnotnecessarytoimmediatelycorrecttorunwaycenterlineasthismaydelaydecelerationeffortsandaggravateskidconditions.Useasmuchrunwayasnecessarytoslowtheairplane.”

ThissectionincorporatedBoeingguidanceondirectionalcontrol.Italsocommandedthereleaseofbrakepressure,whichaidsinrestoringcorneringforcetothemainwheels.Thegoaloftheseactionsistorealigntheairplanewiththerunwaytrackassoonaspossiblesothatbrakingforcescanberestored.Returningtocenterlineisthereforediscouraged.

TheAOM,VOL1,SP.16“GuidelinesforContaminatedRunways”hasbulletpointsfor“landing.”Twoofthesebulletsaddressdirectionalcontrol:

• Ifside-slippingofftherunway,selectreverseidleandreleasebrakestoreturntocenterline.• Aircraftwilltendtodriftofftherunwaynose-firstwithforwardthrustandtail-firstwithreverse

thrust.

Thefirstpointcommandstheuseofreverseidleanddoesnotmentionforwardidle.Italsostatestoreleasebrakes.Theseactionsareto“returntothecenterline.”ReturningtocenterlineisinconflictwiththeguidanceintheFCTMwhichstatesthat“correct[ing]torunwaycenterlinemaydelaydecelerationeffortsandaggravateskidconditions.”

Duringtheaccidentlanding,theaircraftremainednearthecenteroftherunwayastheheadingbegantodriftleft.Astheairplaneturned,thecockpitapproachedtheleftsideoftherunway.Thiswouldbeperceivedbythepilotsastheaircraftdriftingtowardtheupwindsideoftherunway.Thisperceptionwouldbeconfusingtothepilots,asguidanceinthesecondbullet,aswellasthefigurefromtheFCTMbelow,wouldindicatetheairplanewoulddriftdownwindduringreversingonslipperyrunways.


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Figure8:DeltaFCTMguidancereversethrustoperationsincrosswindconditions

TheFCTMinasectionlabeled“ReverseThrust”states:“ThePMshouldmonitorengineoperatinglimitsandcalloutanyengineoperationallimitsbeingapproachedorexceeded,anythrustreverserfailure,oranyotherabnormalities.”Althoughthisaddressedenginelimitsandreverse-thrustabnormalities,itdidnotspecifyacalloutofexcessiveEPRsettingsasaddressedintheBoeingFOB.

2.16.6 Training

IntherecurrenttrainingcyclefromJuly2012toMarch2013,SpecialPurposeOperationalTraining(SPOT)trainingincludedasimulatorscenariowithanun-groovedcontaminatedrunwayoperation.ThefollowingguidancefromTrainingModuleCG603wasprovided:

“Additionalreversethrustshouldbeappliedwhilewatchingcarefullyforsignsofdirectionalcontrolproblems.Remember,applyingreversethrustabove1.3EPRwillpotentiallyblankruddereffectivenessanddegradedirectionalcontrol.

Ifdirectionalcontroliscompromised,reducereversethrusttoidlereverseandholdforwardstickpressuretoregaincenterlinetrack.”

Thepilots’trainingrecordsindicatedthattheyreceivedthistrainingmodule.

Here,theEPRguidanceincludedspecificmentionofthrustabove1.3havingpotentialtoblankrudderanddegradedirectionalcontrol.However,therewasnomentionof1.3asaspecificEPRlimit.

Onceagain,lossofdirectionalcontrolisaddressed.Here,therecoveryguidancesignificantlydifferedfromtheguidanceintheFCTM:“Reducereversethrusttoidlereverse”istrained.Nomentionofthe


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optionofforwardidlewasmade.“[H]oldforwardstick[controlcolumn]”isnotmentionedinanyotherrecoveryguidancetothispoint.Theamountofforwardcolumnisnotdiscussedinguidance,norisanywarningofferedonitseffectonbraking.Thiscouldeasilybeinterpretedthatuptofull-forwardcontrolcolumnwouldbeappropriate.

Thetrainingguidancestatedtheobjective“toregaincenterlinetrack.”ThisisagaininconflictwithguidanceintheFCTM,whichemphasizesrestoringaircraftdirectionandthat“correct[ing]torunwaycenterlinemaydelaydecelerationeffortsandaggravateskidconditions.”

Theneteffectofthisconflictinguidanceandtrainingforlossofdirectionalcontrolwasthateffectivepilotactioninsuchaneventwouldbeverylikelyunpredictableor,worse,couldaggravatetheconditionthroughimproperactionortheinabilitytoreactatall.

Theguidancebelowdescribesthatitisadvisabletoconsiderdelayingtheuseofthethrustreversers.Thiswillcauseatradeoffbetweentheshortestachievablestoppingdistanceandensuringdirectionalcontrolismaintained.

“Landasearlyinthetouchdownzoneaspossible.”39

“Ifdirectionalcontroliscompromised,reducereversethrusttoidlereverseandholdforwardstickpressuretoregaincenterlinetrack.”40

“Onwet,contaminated,orslipperyrunways,immediatelyafternose-geartouchdown,maximizeantiskidbrakingoperationbyapplyingfullbrakepressuresmoothlyandsymmetricallywhileapplyingreversethrusttotheidlereversedetent.Afterreversethrustsymmetryisverified,graduallyincreasereversethrustasrequired.Reversethrustshouldbeappliedsmoothlyandsymmetricallyto1.3EPRassoonaspossiblesincethereversethrusteffectivenessisgreatestathigherspeeds.”41

“Note:Considerdelayingthrustreverserdeploymentuntilnosewheeltouchdown,sothatdirectionalcontrolisnotaffectedbyasymmetricdeployment.”42

“ReverseThrustandCrosswind(AllEngines):Thisfigure43showsadirectionalcontrolproblemduringalandingrolloutonaslipperyrunwaywithacrosswind.Astheaircraftstartstoweathervaneintothewind,thereversethrustsideforcecomponentaddstothecrosswindcomponentanddriftstheaircrafttothedownwindsideoftherunway.Also,highbrakingforcesreducethecapabilityofthetirestocorner.”44

39DeltaOperationsManualVol1,SP16.1440DeltaTrainingModuleCG60341DeltaFCTM,page6.1642DeltaFCTM,page6.1243SeeFigure844DeltaFCTM,page6.25


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2.17 SpecialWinterOperationsAirport(SWOA)

DeltadesignatesSWOAairportsduetoseveralfactorsincludingclimate,snowfall,orelevation.Additionally,therunwaylength,aswellasairportinfrastructureandtheuseofairportrunwayfrictionmeasuringequipmentistakenintoaccount.AtthetimeoftheaccidentLGAwasnotdesignatedaSWOAairport.Sincetheaccident,DeltahasincludedLGAonthelistofSWOAairports.WiththeguidanceintheSOWAevaluationintheDeltaAirwayManual(AM),thecrewwouldhavenotbeenallowedtolandwiththelatestreportedwindsof020degreesat10kts.Thetailwindcomponentinthesewindconditionswas4knots.TheSWOApilot/dispatcherguidestatedthatifthetailwindcomponentis4knotsormore,takeoffsandlandingsareprohibited.45Therefore,ifLGAhadbeendesignatedasanSWOAairportbyDeltaatthetimeoftheaccident,theflightcrewwouldhavenotbeenabletolandatLGAbasedonthetailwindcomponent.

3.0 Airport

3.1 AirportInformation

LGAwascertifiedbytheFederalAviationAdministration(FAA)asa14CFRPart139airportwithindexDaircraftrescueandfirefighting(ARFF).Theairport’selevationis20.6feet,andtheairporthastworunways:13/31,whichwas7,003feetlong,and04/22,whichwas7,001feetlong.Bothrunwaysweregrooved.

3.2 LGASnowRemovalPlan

LGAhadanapprovedsnowremovalplaninaccordancewith14CFRPart139.313.LGAwasregularlyclosedbetween0000and0600eachday;duringthisovernightshift,therunwaysandtaxiwaysweretreatedwithsolidchemicalsandsandedinpreparationfortheforecastedsnowfall.LGAissuedaNoticetoAirmen(NOTAM)at0745statingthattherunwayhadbeensandedandchemicallytreated.By0851atotalof1.8inchesofsnowhadfallen,andtwoNOTAMswereissuedat0902and0903indicating0.25inchesofwetsnowontherunways.ThesewerethelastNOTAMsissuedpriortotheaccident,whichoccurredat1102.Theflightcrewrequestedafieldreportat0955,whichagainstatedthattherunwayswerechemicallytreated.At1018,theflightcrewwastoldbythedispatcherthatRunway13wasclosedastheairportwassweepingtherunway.Theblueteam46beganclearingtherunwayat1006andcompletedtheclearingat1035,whichwas29minutespriortotheaccident.AtthistimeATIS“Papa”wascurrent.

ATISinformationPapa(special)wasissuedat1024andreportedatemperatureof-3degreesCelsiuswithsnowandfreezingfogand0.25milevisibility.Windswere040at7knots.Itstatedthat“allrunwaysarewetandhavebeensandedanddeicedwithsolidchemical.”Italsostatedthat“allrunwayfield

45DeltaAirwayManual,pageWX.2.2946LGAhadseveralcolorcodedteamsclearingdifferentareasoftheairport.TheBlueteamwasassignedtoclearRunway13/31.


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conditions¼inchwetsnowobservedat1404Z”andthatbrakingactionadvisorieswereineffect.Runway31wasnottreatedwithchemicalsduringthelastclearingoperationperthestatementoftheLGAsnowcoordinator.47ThisinformationisincontradictionwithATIS“Papa”andthefollowingATIS“Quebec.”Duringtheclearingoperation,thesolidchemicalswereclearedofftherunwayandnotreapplied.48

ATISinformation“Quebec”wasissuedat1051andcurrentatthetimeoftheaccident.Itreportedatemperatureof-3degreesCelsiuswithsnowandfreezingfogand0.25milevisibility.Windswere030at11knots.Itstatedthat“allrunwaysarewetandhavebeensandedanddeicedwithsolidchemical”andthatbrakingactionadvisorieswereineffect.Italsostatedthat“allrunwayfieldconditions¼inchwetsnowobservedat1404Z.”

BothATIS“Papa”and“Quebec”statedthattherunwaywassandedandchemicallytreated.However,neitherhadbeendonerecently.Therunwaysnowwasonlybroomed.Thelasttimetherunwaywasactuallychemicallytreatedwasinthemorningbefore0450whentheairportwasclosed.Thesnowcoordinatorstatedthatitwasnotstandardproceduretoapplychemicalsand/orsandduringthelastrunwayclearingpriortoarrivals.Headdedthatiftheyhadchemicaldeicingmaterialintheplowandthebrakingactionreportswerefairorpoor,theywouldhavebeguntreatingtherunway.WhileitiswithinregulationstoissueNOTAMsvalidforlongerperiodsoftimes,duringperiodsofrapidlychangingweather,NOTAMsincludingrunwayconditionsshouldbeupdatedfrequentlyastheconditionsareconstantlychanging.ANOTAMshouldnothaveinformationaboutchemicallytreatedrunwaysiftheinformationisnotaccurate,meaningsuchaNOTAMshouldnotbevalidafteractivitiesthatwouldhaveremovedthechemicalsfromtherunwaysurface.Theairportauthoritydidnotadjustthefieldconditionreport.

LGAdoesnotcloserunwaysforsnowremovalortreatment,butworkson“hotrunways”49meaningtheywaitforgapsinarrivalsanddeparturesinordertominimizeimpactonflightoperations.

Priortothelandingoftheaccidentaircraftat1102,aUnitedAirlines(UAL)A319landedataround1043localtimeandreportedbrakingas“...mediumattouchdownandgettingworsethanthathereonrollout...WearegoingtocallitpoordownherewherewearecomingoffatMike.”Afteradiscussionwiththegroundcontrolleronwhetherfairormediumisthecorrectterminologyofreportingbrakingaction,UAL462repliedthataccordingtotheAeronauticalInformationManual(AIM)thecorrectterminologyismedium.Thegroundcontrollerdisagreedandinsistedthatthenewterminologywasgood,fair,poor,andnilandwantedtoknowifUALFlight462wasreportingfairorpoorontherunway.UALFlight462repliedthatitwaspoorontherunway.UALFlight694landedthreeminutesafterUALFlight462andreportedgoodbraking.ThisgoodbrakingactionreportwasrelayedtotheEnvoyFlight3647CanadairRegionalJet(CRJ)landinganotherfiveminuteslater.TheDALFlight1086crewoverheardconversationonthefrequencyofthepoorbrakingactionreport.TheflightcrewhadadiscussionthattheywouldbeunabletolandwithapoorbrakingreportandbrieflydiscusseddivertingtoAlbany,this

47AirportsGroupFactualReport—Attachment3—NTSBInterviewTranscript,page1848AirportsGroupFactualReport—Attachment3—NTSBInterviewTranscript,page2749AirportsGroupFactualReport—Attachment3NTSBInterviewTranscripts—InterviewwithKevinDauweiler,page66


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includedadiscussiononthefueltheyhadavailable.Subsequently,agoodbrakingactionreportfromaregionaljetwasrelayedtoDALFlight1086,andthecrewoverheardagoodbrakingactionreportfromtheotherUnitedaircraft.

DuringthemorningofMarch5,2015,LGAissuedaNOTAMat0738.50At0557,theMATweatherservicereportednosnowaccumulation.Overthenextseveralhours,thesnowfallratewasinarangeof0.4to0.7inchesperhour.Thisisconsideredheavysnowfall,accordingtotheInternationalCivilAviationOrganization(ICAO)ManualonAutomaticMeteorologicalObservingSystemsatAerodromessection6-2.51Visibilityandprevailingsnowfallratewascorroboratedbyinterviewingtheleadsnowoperatoroftheteamassignedtoaccidentrunway.Theleadoperatorstatedthathecouldnotseetheaccidentaircraftasitrestedpost-accidentfromhispositionattaxiwayDDduetoprevailingvisibilityandnotline-of-sightrestrictions.

3.3 ContinuousRunwayMonitoringRequirement

InAC150/5200-30CdatedDecember9,2008,theFAAcalledforNOTAMSdescribingthechangesinrunwayconditiontobetimely.Thisisthecaseforbothworseningconditionsduetoweatherconditionsandimprovingconditionsduetoactionstakentomitigatesuchconditions.TheACfurtherstatedthattherunwayconditionreportsmustbeupdatedanytimeachangetotherunwaysurfaceconditionoccurs.Changesthatinitiateupdatedreportsincludeweatherevents,theapplicationofchemicalsorsand,orplowingorsweepingoperations.Theairportoperatorsshouldnotallowaircraftoperationsonsuchrunwaysaftersuchactivitiesuntilanewrunwayconditionreportisissuedreflectingthecurrentsurfacecondition(s)ofaffectedrunways.

Duringthesnowevent,LGAAirportdidnotusecontinuousfrictionmeasuringequipment(CFME)devices,whichwerepurchasedandstoredattheairportduetononuseandcalibrationissues.TheuseofCFMEdevicesisrecommendedbytheairporttomonitorfrictiontrendsperAC150-5300-30C.Theairport’soperationsmanagerstatedthatheunderstoodthattheCFMEcouldbeusedasatoolforsnowremovaltrendanalysis,butonthedayoftheaccidenttheywereevaluatingtherunwaybasedontheirobservationsandsnowfallrate.ThisisincontradictiontoLGA’sAirportCertificationManual(ACM)andtrainingvideos,52whichstatedthatLGAutilizesaCFME-typefrictiontestertoconductfrictionreadingswhenconditionsrequiretrendanalysisonafrozenorcontaminatedsurface.TheACMalsocontainedaletterofagreement(LOA)53withtheLGAAirTrafficControlTower(ATCT)statingthatwhenitbecomesapparentthatconditionsmayresultindegradedrunwaysurfacefriction,AirportOperationsmayconductfrictionassessmentsusingwhatevertechniquestheairportdutymanagerorsnowcoordinatordeemappropriate,toincludetactilefeel,vehiclebraking,and/oruseofCFME.54IfCFMEisused,Airport

50AirportGroupFactualReport—Attachment2,page151Lightsnowislessthan1.0mm(0.04inches)/hour;moderatesnowisbetween1.0and5.0mm/hour(0.2inches/hour)52AirportsGroupFactualReport—Attachment853AirportsGroupFactualReport—Attachment7,page354AirportsGroupFactualReport,page10


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OperationswillnotreportMuvalues.Duringthemorningleadinguptotheaccident,therunwayswereonlyevaluatedbasedonobservationsofsnowfallrates,andnoCFMEdevicewasused.

Figure9:LGATruckwithRunwayFrictionTester

TheFAAAdvisoryCircularAC150-5200-30Cistoolax,asitallowsaprocedureusingonlybrakingactionreportstoqualifyas“continuousmonitoring”oftherunwaysurface.Othermethodsareonlyrecommendedandnotmandated.Useoffrictionmonitoringequipmentordecelerometersareonlyrecommendedactionsfortheairport.

Inordertoprovideflightcrewswiththemostcurrentandaccuraterunwayconditionreports,itwouldbegoodpracticetoconductatactileinspectionoftherunwaycondition.Thisallowstheairportoperatortodistinguishbetweenwetsnoworslushanddrysnow.NoprovisionsinAC150-5200-30Crequireatactilemeasurementofsnowdepthsorcondition,whichallowstheairportoperatortoestimatedepthsandconditionswhenissuingNOTAMs;thiswasadmittedbytheLGAairportoperatorasstatedininterviewsthattheyjustleave“0.25-inchclutter”ineveryNOTAMissued,unlessitgetsdeeper.

3.4 Post-CrashFrictionTesting

DeltaAirLineshadrequestedthatapost-crashfrictionmeasurementbeconductedonRunway13,whichwasnotcompletedbytheportauthority.TheairportoperatordidnotcomplywithAC150-5200-


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30C,55oritsownSnowOperationsTrainingvideoguidancebynotconductingapost-accidentfrictiontestforaccidentrunwaybutinsteadcompletedafrictionmeasurementforRunway4-22,nottherunwaytheaccidentactuallyoccurredon.

4.0 SurvivalFactors

4.1 Post-AccidentCrewActions

Accordingtothecrewinterviews,theflightcrewnotedthattherewasnopowertotheaircraftduetotheengineshavingbeenshutdownandthebatteryconnectionsbeingseveredduringtheaccidentsequence.Theflightcrewswitchedonemergencypowerandattemptedtostarttheauxiliarypowerunit(APU)withoutsuccess.Thecaptainattemptedtocontactthecabinanddeterminedthatthepublicaddress(PA)andinterphonewereinoperative.Heopenedthecockpitdoorandestablishedcommunicationswiththecabincrew.Thecaptainstatedthatheinstructedtheflightattendanttoassesstheexits.Hereturnedtohisseatandensuredtheevacuationchecklistwascompleted.

Figure10:DeltaMD-88OperationsManual,EvacuationChecklist

Normally,thecabincrewwouldcommunicatetheirassessmentoftheexitsthroughtheinterphone.Becauseemergencypowerwasunavailabletothecommunicationsystem,thecabincrewhadtowalk55AC150-5200-30C—Section2-6SubpartBandSection5-3,SubpartB,Line3


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throughthecabinandestablishcommunication.Oneflightattendantstatedthatsheattemptedtouseamegaphone,butitdidnotwork.

Thecaptain’spointofcontactwastheforwardflightattendant,andheronlymeansofcommunicationswasthemegaphone.SothecaptainsaidtoevacuatethroughtherightwingexitsonlyontheFO’ssiderightnow,andtheforwardflightattendantinitiatedtheevacuation.56

Theconditionoftheaircraftandthecommunicationsystemcreatedasituationthatwasunusualfortheflightandcabincrew.Therefore,thecrewmembershadtousejudgmentandinitiativetoconductasafeandorderlyevacuation.

4.2 PassengerConduct

Asstatedintheinterviewswiththeflightattendants,therewereseveralpassengersusingtheircellphonesduringthepost-accidentperiod.Flightattendantsexpressedconcernthatthepassengerscouldnothearimportantcommunications.Flightattendant3stated:“SoIstartedtowalkbacktoseeifIcouldusemyexit,thetailcone.ThatiswhenIrealizedeverybody(120+passengers)weretalkingontheircellphones.Itwasveryloud.SoIstartedshoutingcommandsasIwalkedbacktotheafttailcone.Getoffyourcellphones,youneedtolisten.Weneedtoprepareforanevacuation,Getoffyourcellphonesnow!”57Inaddition,therewereseveralpassengerstryingtoretrievetheircarry-onbaggageduringtheevacuation.Theseactionsbythepassengersclearlyinterferedanddelayedtheevacuation,increasingpotentialhazardstopassengersandthecrew.

5.0 ChangesBeingImplementedbytheFAADuetotheTALPAARC

OnMarch5,2015,theeasternUnitedStatesexperiencedasignificantsnowstormwithsnowfallratesofupto1.0inchesperhour.TheNWSwillissueaheavysnowwarningwhensnowfallratesreach4inchesper12hoursor0.33inchesperhour.Inthehourleadinguptheaccident,thesnowfallratewasreportedat0.4inchesperhour.At1651UTC(1151EST)theMarineAirTerminal(MAT)weatherservicereportedatotalof3.4inchesofsnowsincebeginningofthesnowfallat0657ESTand0.7inchesofaccumulationintheprevioushour.

Accordingtothedispatcherresponsiblefortheflightplanning,release,andflightfollowing,therunwaywasonlybroomedandhadnotbeentreatedwithchemicalsandtherewas0.25inchesofsnowontherunway.58TheATIStimestamped1024alsostatedthattherewasa0.25inchesofsnowontherunwayobservedat1404Z.AccordingtotheRunwayConditionAssessmentMatrix(RCAM)includedinthefinalreportoftheTakeoffandLandingPerformanceAssessment(TALPA)AviationRulemakingCommittee(ARC)andtheAC25-32,anyrunwaysurfaceconditiondescriptionwithcontaminationofdryorwet

56OperationsGroupFactualReport—Attachment1—InterviewSummaries,page1857SurvivalFactorsGroupFactualReport—Attachment1—FlightAttendantStatements,page558MeteorologyGroupFactualReport—Attachment1,page1


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snowgreaterthanone-eighthinchiscorrelatedtomediumbrakingaction.59AtthetimeoftheaccidentthisAChadnotbeenpublished.TheeffectivedateoftheACwasDecember12,2015.

AsdiscussedinSection1.1,theflightcrewneeded“good”brakingactiontolandatLGA.IfthesameconditionsexistedtodayasthedayoftheaccidentbasedonthenewTALPAAC,theflightcrewofDAL1086wouldnothavebeenallowedtoland.

6.0 Conclusions

TheNWSforecastedamajorsnowstormfortheMid-Atlanticregionwithestimatedsnowtotalsofupto8inches.SnowhadjustbeguninLGAatthetimeDALFlight1086departedATL.TheaircraftwasdispatchedinaccordancewithFARPart121.195dispatchrequirements.Thisrequiredthedispatchertocalculatelandingperformancebasedonwetrunwayconditionatthedestinationairport.Thisdidnotrequireanycalculationsbasedonsnowcoveredrunwayconditions.Whilethiswasinaccordancewithcurrentregulations,thisputtheflightcrewinapositionwhereitissolelytheirresponsibilitytodeterminetherequiredrunwayconditionatthedestinationforlandingtheaircraft.TheflightcrewofDALFlight1086determinedearlyintheirflightthattheywouldneedabrakingactionreportof“good”inordertolandtheaircraftatLGA.Throughouttheflighttheflightcrewrequestedupdatedfieldconditionsreportstoensurethattheyhaveanaccuratepictureoftherunwayconditionspriortotheirapproach.

Thelandingdistanceassessmentthecrewperformedwasbasedon“good”brakingactionasreportedbyprecedingflights.WhiletheywereawareofapoorreportfromaUnitedAirbus,theyreceivedtwogoodbrakingactionreportsfromthefollowingaircraft,andanotherDALMD-88landedpriortothemwithnobrakingactionreport.Thisconvincedtheflightcrewthatitwassafetolandtheaircraftinthecurrentconditions.

Bothflightcrewmembersexpectedaclearedandchemicallytreated,wetrunwaybasedonthefieldconditionreportstheyhadreceived,buttheyfoundasnowcoveredrunway.TheFCTMstatedthatwhenlandingonaslipperyrunwayto“landasoonaspossible.”Thecaptainadjustedhisaimpointtolandwithinthefirst1,000feetoftherunway.CorrelatedFDRandperformancedataestimatedthetouchdownpointataround600feetfromthethreshold.ThisplacedtheaircraftonthepiersectionofRunway13,whichhadaccumulatedalayeroficeduetothereportedweatherconditionsoffreezingfogforthepreceding3hours.

Theaircrafttoucheddowninthefirstsectionofthetouchdownzone,whichwasearlierthanonanormalflight.Itismorecommonforaircrafttofollowtheglideslopetotheglideslope/runwayinterceptpoint.Theglideslopeinterceptpointiscloseto1,000feetfromthethreshold,whichisaftertheendofthepier.Therefore,DALFlight1086spentaperiodoftimeduringitsinitialrolloutonanicysurface.

59AC25.32LandingPerformanceDataforTime-of-ArrivalLandingPerformanceAssessments—Table2,page14


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Thislandingonanicysurfaceledtoadelayinwheelspin-up,resultinginnon-deploymentoftheautospoilers.TheFOdeployedthespoilersmanually,whichwithoutwheelspin-uponlydeployedtheflightspoilerpanels.Movementofthespeedbrakehandleactivatedthemaximumautobrakes.Abnormalantiskidoperationwouldbeexpectedwithlow-tono-wheelspin-upaccelerationsonalow-tono-tractionrunwaysurfaceanddelayedspoilerdeploymentattouchdown.60

Shortlyaftertouchdownwiththenosestillintheair,thethrustreversersweredeployed.Nose-strutcompression(WOW)occurredat11:02:19.Withinabout4seconds,theleftengineEPRrosetoapeakof2.09andtherightengineEPRto1.91.AccordingtoBoeing,rudderandverticalstabilizerblankingoccurswhenEPRsettingsexceed1.6.Theelevatorsmovedtoanalmostcompletetrailingedgedownposition.Thisexceededtheamountofforwardcontrolcolumncommandedbytheflightcrew.Thiselevatorpositionreducedthedownwardforceonthemaingear,furtherlimitingbrakingandcorneringforcesavailableandseverelylimitedthelongitudinaldirectionalcontrollabilityoftheaircraft.

Theaircraftbegantograduallyyawleft;however,thisrateincreasedrapidly.Duringthistime,theaircraftremainedwithin5feetoftherunwaycenterline,basedonASR,essentiallyslidingdowntherunwaytrack.AstheFOrecognizedchangesinheading,hecalled“comeoutofreverse”threetimeswithintwoseconds.Thecaptainimmediatelystowedthereversers.Withthereversersstowed,ruddereffectivenesswasregained.Afterthereverserswerestowed,theEPRsettingswerestillatconsiderablyhighrange,resultinginforwardthrust,pushingtheaircraftinthedirectionofitsheading.Approximately0.5secondslater,amomentaryincreaseintherightbrakingsystempressurewasrecorded,consistentwithapplicationofmanualbraking;thisactiondisengagedtheautobrakes.Withthewheelsturning,corneringforceswererestored.Thecaptainappliedrightrudder,andtheleftyawwasarrested.Theaircraftheadingbegantoturntowardrunwayheading.Beforethecaptainwasablerecoverfullcontrol,theaircrafttrackedofftherunwaysurface.Oncetheaircraftdepartedtherunwaysurface,thecrewhadverylittlecontrolovertheaircraft’sdirectionandspeed.

Thepier’sicyconditionandtherunwaysnowcoveredsurfacecreatedachallengingenvironment,whichreducedrunwayfriction,contrarytotheinformationthecrewhadreceivedfromdispatchandATC,asreportedbytheairportoperator.TheCVRandtheACARSreportsshowthatthecrewcontinuouslyinquiredaboutfieldconditionreportsinordertomakeasafeassessmenttolandatLGA.TheATIScurrentatthetimeoftheaccident,aswellasfieldconditionreports,statedthattherunwaywaswet,sanded,anddeicedwithsolidchemicals.Furthermore,itwasreportedthatallrunwayfieldconditionswereobservedwith0.25inchesofwetsnow.However,thelasttimeitwaschemicallytreatedwasat0450.Whentherunwaywasbroomedabout40minutespriortotheaccident,allappliedchemicalswerebrushedoff,andnochemicalswerereapplied.Therunwayhadneverbeensanded.

LGAwasusingcontinuousmonitoringtoassessfieldconditionsinaccordancewithAC150-5200-30C.Continuousmonitoringallowstheairporttousebrakingactionreportsbypilotsastheirsolemethodforevaluatingrunwaysurfacecondition.However,thismethoddoesnottakeinthevariablesofaircrafttypeorthepilot’sperceptionofhoweffectivethebrakingactuallywas.

60NTSBAircraftAccidentReport—AAR-01/02,page93


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Eightminutesafterbroomingtherunway,thefirstaircraftlandedandreportedbrakingaction“poorontherunway”toLGATower.Thesnowcoordinatoroverheardtheremarkanddidnottakeaction.InaccordancewithAC150-5200-30C,noactionwasrequireduntilasecondconsecutivepoorreportisreceived.ThePortAuthoritywasrequiredtoprovideupdatedfieldreportswithchangingconditions.Insteadofprovidingnewupdatedreports,thePortAuthorityusedthesame“canned”report,whichincluded0.25inchesofwetsnowontherunwayandthattherunwaywassandedandchemicallytreated.Pilotshavetorelyonaccurateconditionreportingtomakeanassessmentofthelandingconditionsforthetimeofarrival.

TheDeltadispatcher’sstatementshowedhehadoverheardaradioconversationbetweenLGATowerandthePortAuthority,justpriortoDALFlight1086’sapproach,thattherunwayswerenotsandedorchemicallytreatedandthattherewasstill0.25inchesofsnowontherunway.Thisinformationwasnotrelayedtotheflightcrew.

AC150-5200-30C,highlysuggestedCFMEtobeusedbytheairportfortrendmonitoringofasurfaceconditionworsethandry.Theairportchosenottousethisequipmentduringthissnowevent.CFMEequipmentprovidesaccuratetrendreportsthatcanonlybeusedbytheairporttodetermineifarunwayneedsclearing.Additionally,theairportdidnotcomplywithAC150-5200-30C,whichrequiresapost-accidentfrictionmeasurementoftheaccidentrunway.ALPAagreeswiththeNTSBPerformanceStudyconclusion,whichstates:“Thedatawasincompleteortheeffectsoftheseforcesontheaircraftwerenotmeasuredand/oraccuratelymodeledfortheexactcontributionofeachtobedetermined.Whatdatawasavailabledidnotmakeanysingleeventorenvironmentalfactorseemlikelyonitsowntobeabletoimparttheyawingmomentexperiencedbytheaccidentaircraft.Itislikelythatacombinationofasymmetricthrust,crosswind,andrunwayfrictioncausedtheaircrafttodeviatefromtherunwayheading.”Therewasnosingleeventthatcausedthisaccident,butaseriesoffactorsallplayedarole.


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7.0 Findings:

1. Theflightwasoperatedasa14CFRPart121Scheduled,Domesticflight.

2. Theflightcrewwasproperlycertificatedandqualifiedinaccordancewithapplicablefederalregulations.

3. Theairplanewasproperlycertified,equipped,andmaintainedinaccordancewithfederalregulations.

4. Theaircraftwaslegallydispatchedtoanairportwheretheforecastedweathermadeasafelandingimprobable.

5. Theaircraftlandedwithin600feetoftherunwaythresholdonthepier,whichwassusceptibletofreezingbeforetherestoftheasphaltrunwaysurface.

6. Thepiersectionoftherunwayhadaccumulatedice.

7. Autospoilersdidnotdeployautomaticallybecausemainwheelspin-upwasdelayedordidnotoccur.

8. Abnormalantiskidoperationwouldbeexpectedwithlow-tono-wheelspin-upaccelerationsonalow-tono-tractionrunwaysurfaceanddelayedspoilerdeploymentattouchdown.

9. ThrustreversersweredeployedwithmaximumEPRreaching2.09ontheleftand1.91ontheright.

10. Theelevatortrailingedgewasinthedownpositionforagoodportionofthelandingroll,whichreducedthedownwardforceonthemainlandinggear.

11. NOTAMsandATISstatedthattherunwaywascoveredwith0.25inchesofsnow.

12. AccordingtothenewTALPAguidance,0.25inchesofsnowwouldbeequivalenttomediumbrakingaction.

13. Runwayswerechemicallytreatedat0450,yetinallofthefollowingNOTAMsandATIS,theremarkforchemicallytreatedrunwaysremained.

14. UAL462reported“poor”brakingaction.

15. PortAuthoritydidnotactupon“poor”brakingactionreportanddidnotassessorchemicallytreattherunway,butwasnotrequiredto.

16. PortAuthorityonlyassessedtheconditionoftherunwayusingthesnowfallrateandpilotreports.

17. FAAallowsthecontinuousfrictionmeasuringrequirementtobefulfilledbyonlyusingPIREPs.


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18. Nopost-crashfrictionmeasurementwasconductedonRunway13,despitehavingbeenrequestedbyDeltaAirLineandrequiredAC150-5200-30C.

19. LGAdoesnotuseanyCFMEtomonitorrunwayfrictionandrunwaycondition.

20. Notactileinspectionoftherunwaywasconducted.

21. Therewasnosingleeventorenvironmentalfactorthatseemslikelyonitsowntobeabletoimparttheyawingmomentexperiencedbytheaccidentaircraft.

22. Itislikelythatacombinationofasymmetricthrust,crosswind,andrunwayfrictioncausedtheaircrafttodeviatefromtherunwayheading.

23. Theusageofcellphonesandretrievalofpersonalbelongingsbysomepassengersinterferedwiththeevacuation.


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8.0 Recommendations:

TotheFAA:

1. RequirePIREPSwith“lessthangood”brakingreportstoberelayedtothefollowingaircraftlandingonthesamerunwayuntilarunwayassessmentcanbecompletedbytheairport

2. Requireactualcontinuousrunwayconditionmonitoring(AC150-5200-30C)andnotonlyrelyingonpilotreportingorassessmentusingsnowfallrates.

3. RunwayconditionreportsshouldbeinaccordancewithrecommendationsfromTakeoffandLandingPerformanceAssessment(TALPA)AviationRulemakingCommittee(ARC).

4. Requiretactileinspectionofrunwaysduringwinterweatherevents,asthisprovidesvaluablefeedbacktoflightcrewastothetypeofcontaminationthatcanbeexpectedonarunway.

5. RequirePOIsofalloperatorsofMD-80seriesaircraftstoreviewanddeterminethattheseoperators’flightmanualsandtrainingprogramscontaininformationonthedecreaseinruddereffectivenessduringtheuseofreverse-thrustpowerinexcessofidlereverseandhigher.

6. RequirealloperatorsofMD-80seriesaircrafttorequireacalloutifreverse-thrustpowerexceedstheoperators’specificenginepressureratiosettings.

7. Requireall14CFRPart121operatorsofthrustreverser-equippedaircrafttoincorporateaprocedurerequiringthepilotmonitoringtocheckandconfirmthethrust-reverserstatusimmediatelyaftertouchdownonalllandings.

8. Developandissueformalguidanceregardingstandardsandguidelinesforthedevelopment,delivery,andinterpretationofrunwaysurfaceconditionreports.

9. Requireestablishmentofaminimumstandardfor14CFRPart121operatorstouseincorrelatinganaircraft’sbrakingabilitytobrakingactionreportsandrunwaycontaminanttypeanddepthreportsforrunwaysurfaceconditionsworsethanbareanddry.

10. Requireall14CFRPart139certificatedairportoperatorstoincludeintheirairport’ssnowandicecontrolplanabsolutecriteriafortypeanddepthofcontaminationandrunwayfrictionassessmentsthat,whenmet,wouldtriggerimmediateclosureoftheaffectedrunwaytoaircarrieroperations.Frictionassessmentsshouldbebasedonpilotbrakingactionreports,valuesobtainedfromgroundfrictionmeasuringequipment,andestimatesprovidedbyairportgroundpersonnel.

11. Requirethatinitialandrecurrentairtrafficcontrollertrainingprogramsstresstheimportanceoftransmittingallknowncontaminatedrunwayconditioninformationtodepartingandarrivingflights,thata“medium”or“poor”brakingactionreportfromapilotmayindicateconditions


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thatarehazardousfordifferentaircrafts,andthatdepartingandarrivingpilotsshouldbeinformedwhennorecentlandingbyacomparableaircrafthasbeenmade.

12. Requirethatcontrollersdisseminate“poor”and“nil”brakingactionreportspromptlytoairportmanagementandtoalldepartingandarrivingflightsuntilairportmanagementreportsthatthebrakingactionis“good.”

13. Requiredispatcherstoprovideallupdatedfieldconditionsduringcontaminatedrunwayoperations.

14. Requirethatpriortodispatch,suitablerunwaysshouldbeevaluatedforlandingperformancebasedonforecastedsurfaceconditionsatthetimeofarrival,includingforecastedsnowfallandaccumulationrates.

ToDeltaAirLines:

1. Eliminateconflictingguidanceinthemanualsrelatedtolandingoncontaminatedrunways.

2. Includeallpertinentinformationandoperatingguidanceforslipperyandcontaminatedrunwayoperationinonesectionofamanual.

ToDeltaAirLinesandBoeing:

1. Provideeffectiveandobjectiveguidanceforspecificaircraftoperationsrelatedtolandingoncontaminatedrunways.

ToBoeing:

1. RequiretheuseofidlereverseasthemaximumreversepowerforMD-80seriesaircraftundercontaminatedrunwayconditions,exceptinanemergencyinwhichdirectionalcontrolcanbesacrificedfordecreasedstoppingdistance.

air line pilots association, international national

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