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COMPARATIVEREPORT,Volume2

U.S.JHIMDATDatatoU.S.JHSATData

U.S.JointHelicopterImplementationMeasurementDataAnalysisTeam

To

TheUnitedStatesHelicopterSafetyTeam

August2014

TheU.S.JHSATanalyzed523U.S.registeredhelicopteraccidentsthatoccurredinCY2000,CY2001andCY2006(JHSATdata).TheU.S.JHIMDATanalyzed415U.S.registeredhelicopteraccidentsthatoccurredinCY2009‐2011(JHIMDATdata).ThisreportcontainsthecomparativeJHIMDATtoJHSATdataanalysis.Thepurposewastoidentifydifferencesofstatisticalsignificance.Bynotingareasofimprovement,regression,andstagnation,thisanalysisallowedtheopportunityforastrategicapproachtofuturehelicopteraccidentratereductionefforts.

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TableofContents

U.S.JHIMDATMembers.........................................................................................................................................................3

Description.................................................................................................................................................................................4

Industry.......................................................................................................................................................................................6

Activity.........................................................................................................................................................................................8

IndustryandActivityPairs................................................................................................................................................11

OccurrenceCategory............................................................................................................................................................15

FatalandNon‐FatalAccidentProportionsbyOccurrenceCategory...............................................................17

OccurrenceCategory’sInfluenceonFatal&Non‐FatalAccidents....................................................................19

Sub‐OccurrenceCategory...................................................................................................................................................24

JointAircraftSystem/Component(JASC)Codes......................................................................................................27

InitiatorofSystemComponentFailure(SCF)............................................................................................................29

TypeEngineInstalled..........................................................................................................................................................31

AccidentsbyMonth..............................................................................................................................................................32

WeatherCondition................................................................................................................................................................34

FatalandNon‐FatalAccidentCountsbyWeatherCondition..............................................................................35

WeatherCondition’sInfluenceonFatal&Non‐FatalAccidents........................................................................36

LightCondition.......................................................................................................................................................................37

AccidentsbyPilot’sFlightHours....................................................................................................................................38

InfluenceofMake/ModelFlightHoursonFatal&Non‐FatalAccidents........................................................45

SummaryandConclusions................................................................................................................................................46

References................................................................................................................................................................................48

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ListofTables

Table1.IndustryComparison...........................................................................................................................................7Table2.ActivityComparison...........................................................................................................................................10Table3.IndustryandActivityPairsComparison...................................................................................................12Table4.OccurrenceCategoryComparison...............................................................................................................16Table5.Fatal/Non‐FatalLossofControl(LOC)......................................................................................................17Table6.Fatal/Non‐FatalAutorotation(AUTO).......................................................................................................17Table7.Fatal/Non‐FatalSystemComponentFailure(SCF)...............................................................................17Table8.Fatal/Non‐FatalStrike......................................................................................................................................17Table9.Fatal/Non‐FatalFuelIssue..............................................................................................................................18Table10.Fatal/Non‐FatalVisibility(VIS)Issue......................................................................................................18Table11.Fatal/Non‐FatalFire........................................................................................................................................18Table12.Fatal/Non‐FatalControlledFlightIntoTerrain(CFIT)....................................................................18Table13.LossofControl(LOC)OccurredComparedtoNoLOCOccurred.................................................20Table14.Autorotation(AUTO)OccurredComparedtoNoAUTOOccurred..............................................20Table15.SystemComponentFailure(SCF)OccurredComparedtoNoSCFOccurred..........................21Table16.StrikeOccurredComparedtoNoStrikeOccurred.............................................................................21Table17.FuelIssueOccurredComparedtoNoFuelIssueOccurred.............................................................21Table18.Visibility(VIS)IssueOccurredComparedtoNoVISIssueOccurred..........................................22Table19.FireOccurredComparedtoNoFireOccurred.....................................................................................22Table20.CFITOccurredComparedtoNoCFITOccurred...................................................................................23Table21.Sub‐OccurrenceCategoryComparison...................................................................................................25Table22.ComparisonofConsolidatedJASCCodes................................................................................................27Table23.JASCCodesbyMajorSystemIdentifier(First2Digits)....................................................................28Table24.InitiatorofSystemComponentFailures(SCFs)...................................................................................30Table25.TypeEngineInstalledComparison...........................................................................................................31Table26.AccidentsbyMonthComparison...............................................................................................................33Table27.WeatherComparison......................................................................................................................................34Table28.VMCOnlyAccidents.........................................................................................................................................35Table29.IMCOnlyAccidents..........................................................................................................................................35Table30.VMCandIMCRelatedtoInjuryOutcome...............................................................................................36Table31.LightConditionComparison........................................................................................................................37Table32.AccidentsbyRotorcraftFlightHoursforPilotswith<or=7,500Hours..................................39Table33.AccidentsbyRotorcraftFlightHoursforPilotswith<or=600Hours......................................41Table34.AccidentsbyMake/ModelHoursforPilotswith<or=4,500Hours..........................................42Table35.AccidentsbyMake/ModelFlightHoursforPilotswith<or=1,000Hours.............................43

ListofFigures

Figure1.DistributionofAccidentsbyPilots’RotorcraftFlightHours............................................................40Figure2.DistributionofAccidentsby‐Pilots'Make/ModelFlightHours.....................................................42Figure3.AccidentsbyMake/ModelFlightHoursforPilotswith<or=1,000Hours..............................44

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U.S.JHIMDATMembersThefollowingJHIMDATMemberorganizedthedata,conductedthecomparativeanalysis,andwrotethecomparativereportbetweentheJHIMDATandJHSATdata.

Name Company/OrganizationLeeRoskop FAARotorcraftStandardsStaff

ThefollowingJHIMDATMemberscontributedtooneorallofthefollowingactivities:analysisoftheJHIMDATdata,reviewofthecomparativereport,anddevelopmentofsummaryandconclusions.

Name Company/Organization PositionSteveGleason SikorskyAircraftCorporation JHIMDATCo‐Chair(Industry)ScottTyrrell FAARotorcraftStandardsStaff JHIMDATCo‐Chair(Government)EricBarnett FAARotorcraftStandardsStaff MemberScottBurgess Embry‐RiddleAeronauticalUniversity MemberTomCaramancio BoeingMilitaryAircraft MemberMarkColborn DallasPoliceDepartment MemberMunroDearing NASA MemberRoyFox BellHelicopterTextron‐Retired MemberGaryHowe BellHelicopterTextron MemberLeeRoskop FAARotorcraftStandardsStaff MemberBillWallace BillWallace&Associates Member

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DescriptionIn2006,theU.S.JointHelicopterSafetyAnalysisTeam(JHSAT)begananalysisworkonU.S.accidentsthatoccurredincalendaryear2000.Afterpublishingareportwiththeresultsoftheirwork,theJHSATproceededtocompletecomparableanalysisontheU.S.accidentsthatoccurredin2001andfollowedcompletionofthatprojectwithanalysisof2006.In2011,theJHSATconsolidatedtheresultsofallthreerespectiveyearsintoacompendiumreport(hereafterknowninthisreportas“JHSATdata”).TheJHSATdataestablishedabaselineforfutureU.S.helicopteraccidentanalysis.

Asafollowuptothecompendiumreport,theU.S.JointHelicopterImplementationMeasurementandDataAnalysisTeam(JHIMDAT)attemptedtomeasureprogressbycomparingtheJHSATdatatoanalysisperformedonthethreecalendaryears2009‐2011(hereafterknowninthisreportas“JHIMDATdata”).AnalysisoftheJHIMDATdataremainedconsistentwiththeJHSAT’smethodology.However,theextensivedepthofanalysisperformedontheJHSATdatarequiredmonthlymeetingsofoneweekdurationthatwerenolongerfeasibleforanalysisoftheJHIMDATdata.TheJHIMDATtransitionedtoquarterlymeetingsconsistingofamuchsmallerteamcompositionthantheoriginalJHSAT.Toaccountfortherealitiesofasmallerteamthatmetlessfrequently,theJHIMDATreducedthescopeoftheanalysiseffort.Theteamaccomplisheda“highlevel”analysisofthethreeyearsfrom2009‐2011throughquarterlymeetingsconductedovera9monthperiod.

TheJHIMDAT’spreferencewouldhavebeentouseratebasedcomparisonsintheiranalysis.Theratewouldhavebeencalculatedusingaccidentcountsasthenumeratorandflighthoursasthedenominator.However,whileitwaspossibletomakesomereasonableestimatesforthetotalU.S.rotorcraftflighthours,itwasnotpossibletoaccuratelyrefinethatflighthourestimateacrossthenumerousdifferentanalysisareasusedbytheJHIMDAT.Withthislimitation,theJHIMDATmadecomparisonsintheirresearchbasedonaccidentcountsthatwereconvertedtopercentagestoexpressfrequency.

TheJHIMDAT’sintentwastofindwheremeaningfuldifferencesexistedbetweentheJHIMDATdataandtheJHSATdata.Areaswhereimprovementoccurredwerecandidatesforexploringsuccessfulimplementationmeasuresforuseinotherareaswhereprogresswaslesssubstantial.Areaswhereregressionoccurredorstagnationwasevidentwerecandidatesforadaptingdifferentinterventionstrategiestoencourageimprovement.Ineithercase,adjustmentscouldbemadetofurthertheprogresstowardthe80%accidentratedecreasesoughtbytheIHST.InitialcomparisonoftheJHIMDATdataandJHSATdatashoweddifferencesdidexist.However,theJHIMDATsoughttofurtheridentifyareaswherestatisticallysignificantdifferencesexisted.Theteamoptedforachisquaredanalysistosupportthispurpose,basedontheJHSAT’sandJHIMDAT’smethodoforganizingtheaccidentanalysisdataaccordingtoanominalscale.“Nominalscale”describesagroupingofdataintovariouscategoriesbasedonsomecommoncharacteristic.Apartiallistofexampleswouldincludethefollowing:1)“Industry”,suchasPersonal/Private,Instructional/Training,orAerialApplication;2)“Activity”descriptions,suchasPositioning/RTB,Instructional/Training(Dual),orMaintenance/Testflight;and3)“OccurrenceCategories”,suchasLossofControl,Autorotation,orSystemComponentFailure.

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Thechisquaredanalysisconsistedofeithera“goodnessoffit”test(mostcases)ora“testofhomogeneity”(afewcases).ThegoodnessoffittestallowedtheteamtodirectlycompareonegroupofJHIMDATdatatothecorrespondinggroupofJHSATdatatoassessstatisticaldifferences.Thetestofhomogeneitywasaslightlymorecomplexapproachthattheteamusedforafewlimitedcaseswherethegoalwastoexaminetwocategories(e.g.,VMCorIMC)againsttwoothercategories(e.g.,fatalaccidentornon‐fatalaccident).ThetestofhomogeneitydidnotallowthesamedirectcomparisonofJHIMDATdatatoJHSATdataaswaspossiblewiththegoodnessoffittest.However,aviablecomparisonwasstillpossibleinthesecasesaccordingtothefollowingmethod.TheteamfirstappliedthetestofhomogeneitytoidentifywhetherastatisticaldifferenceexistedwithintheJHSATdata,thenappliedthesametestofhomogeneitytothecorrespondingcategorieswithintheJHIMDATdata,andconcludedbyassessingiftheresultsbetweenthetwodatasetsweresimilarordifferent.Alsoaspartofthechisquaredanalysis(forbothgoodnessoffittestandtestofhomogeneity),theteamoftenusedthestandardizedresidualtodeterminewhatspecificnominaldatawasamajorcontributortodrivingthestatisticaldifference.Forexample,ifastatisticaldifferencewasfoundintheareaofindustrysectors,thestandardizedresidualwouldidentifythespecificindustrysectorsmostresponsibleforthestatisticaldifference.

Foreachanalysisscenariointhisreport,theJHIMDATusedthechisquaredcriticalvaluesassociatedwithp=.01.The“pvalue”isassociatedwiththeprobabilityofrejectinganullhypothesisthatisactuallytrue.Thepvaluesassociatedwithmeasurementsofstatisticalsignificancearetypically.05orless,sotheJHIMDAT’suseofp=.01wasconsistentwithusingarigorousstandardtoassessstatisticalsignificance.InthecaseoftheJHIMDATandJHSATdatacomparison,thenullhypothesisineachcasewasthattherewasnotadifferencebetweenthenominaldatafromtheJHIMDATascomparedtothenominaldatafromtheJHSAT.Inordertorejectthenullhypothesisforanyoftheareasstudiedinthisreport,thecalculatedchisquaredvaluehadtoexceedthechisquaredcriticalvalueforp=.01.AnytimetheteamfoundastatisticaldifferenceintheJHIMDATandJHSATdata,useofp=.01meantthattherewasa1%(orless)probabilitythatourconclusionwasincorrectandastatisticaldifferencebetweenthedatadidnotexist.

AgoaloftheJHIMDATwastoproduceareportthatwassuccinctandeasilyreadsothatresultsfromthereportcouldbequicklytranslatedbythereadersintoimplementation.Wesoughttoavoidacumbersomeandoverlydetaileddocumentthatwouldneverberead.Consistentwiththisapproach,theteamseparatedthecomparativeanalysisintotwovolumes.TheintentwastoensureVolume1emphasizedthemostimportantaspectsofthecomparativeanalysis.TheteamintentionallytruncatedmostofthetablesinVolume1suchthatonlythemostfrequentlycitedareasintheanalysiswerelisted.Thedatasuggestedtheseareascouldhavethemostsignificantimpactonfutureaccidentreductionefforts.Volume2ofthecomparativeanalysishasthecompletedatatablesforthereaderwhowouldliketoexploretheanalysisatanadditionallevelofdetail.Volume2alsoincludessomedatatablesthatwerelimitedtoatextualsummaryinVolume1.

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IndustryIndustrydescribedthetypeofworkoroperationwherethehelicopteristypicallyused.TheteamcategorizedeachaccidentfromboththeJHSATdataandJHIMDATdatabyIndustryintooneoffifteenpossibleoptions.Table1liststheIndustrycategoriesfromtheJHIMDATdataalongsidetherespectivepercentagesfromtheJHSATdata.TheIndustrycategoriesarelistedindescendingorderoffrequencybasedontheJHIMDATcolumn.

ThereweretwoseparatechisquaredanalysesaccomplishedasrelatedtoIndustry.

1) TheteamanalyzedtheaggregategroupofJHIMDATaccidentsascategorizedbyIndustryagainsttheaggregategroupofJHSATaccidentscategorizedbyIndustry.Theconclusionwasthetwodatasetswerestatisticallydifferent.MajorcontributorstothestatisticaldifferenceweretheincreaseintheproportionofAerialApplicationaccidentsandthedecreasesintheproportionsofFirefighting,Logging,andElectronicNewsGatheringaccidents.

2) Theteamconductedaseparate,individualanalysisofeachspecificIndustrysegment(1degreeoffreedom).AsshowninTable1,statisticallysignificantdifferencesexistedforthefollowingindustries:AerialApplication(increased),Firefighting(decreased),andLogging(decreased).

a. Thefollowingisanexampleofhowtheteamstructuredtheindividualchi

squaredanalysis.

%ofAccidentsCY00‐01,06

IndustryAccidentsObservedCY09‐11

AccidentsExpectedCY09‐11

ChiSquaredValue

Conclusion

18.5% Personal/Private 86 7781.5% AllOtherIndustries 329 338

0.256 >0.01,NotSignificant

b. Theteamcouldnotperformanindividualchisquaredanalysisforthefollowingtwoindustrysectors:UtilitiesPatrol/ConstructionandElectronicNewsGathering.Inbothofthesecases,the“expected”numberofeventsfromthechisquaredanalysiswasbelow10.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthan10“expected”eventsforcasesof1degreeoffreedom.

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Table1.IndustryComparison

20.7% (86) 18.5% (97)20.5% (85) 17.6% (92)15.7% (65) 10.3% (54)8.0% (33) 7.6% (40)7.5% (31) 7.5% (39)5.5% (23) 6.5% (34)5.1% (21) 5.0% (26)4.1% (17) 4.0% (21)3.6% (15) 5.9% (31)2.9% (12) 4.2% (22)2.4% (10) 2.7% (14)2.4% (10) 2.1% (11) X1.0% (4) 3.6% (19)0.5% (2) 2.7% (14)0.2% (1) 1.7% (9) X

DenotesstatisticallysignificantincreaseinproportionofaccidentsfromJHSATtoJHIMDAT

DenotesstatisticallysignificantdecreaseinproportionofaccidentsfromJHSATtoJHIMDAT

DenotesnostatisticallysignificantchangeinproportionofaccidentsfromJHSATtoJHIMDAT

X Excludedfromindividualchisquaredanalysis

JHSAT(CY00‐01,06):523Accidents

LawEnforcementBusinessAerialObservationAirTour/Sightseeing

Industry

Personal/PrivateInstructional/TrainingAerialApplicationEmergencyMedicalServicesCommercial

UtilitiesPatrol/ConstructionFirefightingLoggingElectronicNewsGathering

JHIMDAT(CY09‐11):415Accidents

OffshoreExternalLoad

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ActivityActivityisdifferentfromIndustryinthatitdescribedthespecificfunctionthehelicopterwasengagedinatthetimetheaccidentactuallyoccurred.TheteamcategorizedeachaccidentfromboththeJHSATdataandJHIMDATdatabyActivityintooneoftwenty‐sevenpossibleoptions.Table2liststheActivitycategoriesfromtheJHIMDATdataalongsidetherespectivepercentagesfromtheJHSATdata.TheActivitycategoriesarelistedindescendingorderoffrequencybasedontheJHIMDATcolumn.

ThereweretwoseparatechisquaredanalysesaccomplishedasrelatedtoActivity.

1) TheteamanalyzedtheaggregategroupofJHIMDATaccidentsascategorizedbyActivityagainsttheaggregategroupofJHSATaccidentscategorizedbyActivity.Theconclusionwasthetwodatasetswerestatisticallydifferent.AmongsomeofthemajorcontributorstothestatisticaldifferencewastheincreaseintheproportionofaccidentsinthefollowingActivities:Instructional/Training(Dual),Personal/Private,andInstructional/Training(Solo).a. Alimitationexistedincomparingtheaggregategroups.Forcaseswheredegreesof

freedomaregreaterthan1,bestpracticefromstatisticalreferencesourcessuggestedthatnomorethan20%oftheoveralldatasetshouldhave“expected”numberofeventslessthanfive.Nineoutoftwenty‐seven(33%)oftheActivitycategorychoiceshad“expected”numbersofeventslessthanfiveinthechisquaredanalysis.Tocorrectforexceedingtherecommended20%,theteamconsideredtwodifferentapproaches.i. Inthefirstapproach,theteamconsolidatedthenineActivitycategorieswith

“expected”numberofeventsbelowfiveeventsintoasingle“lowevent”Activitycategoryforpurposesoftheaggregatechisquaredanalysis.Afterorganizingthedatainthismannerandconductingthestatisticalanalysis,theteamobservedthetwodatasetswerestatisticallydifferent.

ii. Inconsideringasecondapproach,theteamobservedthattheninecategorieswith“expected”numberofeventslessthanfiveaccountedforlessthan10%oftheaccidentsineithertheJHSATdataortheJHIMDATdata.Forpurposesofthechisquaredanalysis,theteamexcludedtheninecategoriesandcomparedonlytheremainingeighteencategorieswith“expected”numberofeventsgreaterthanfive.Afterorganizingthedatainthismannerandconductingthestatisticalanalysis,theconclusionwasconsistentwiththefirstapproachinfindingthetwodatasetswerestatisticallydifferent.

2) Theteamconductedaseparate,individualanalysisofeachspecificActivitycomparing

theJHIMDATdatatotheJHSATdata.TheresultsareinTable2.

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a. Thefollowingisanexampleofhowtheteamstructuredtheindividualchisquaredanalysis.

%ofAccidentsCY00‐01,06

IndustryAccidentsObservedCY09‐11

AccidentsExpectedCY09‐11

ChiSquaredValue

Conclusion

14.0% Instructional/Training(Dual) 80 5886.0% AllOtherActivities 335 357

0.002 <0.01,Significant

b. Theteamcouldnotperformanindividualchisquaredanalysisforthirteenofthetwenty‐sevenActivitycategories.Ineachofthethirteencases,the“expected”numberofeventsfromthechisquaredanalysiswasbelowten.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthanten“expected”eventsforcasesof1degreeoffreedom.

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Table2.ActivityComparison

19.3% (80) 14.0% (73)17.8% (74) 12.4% (65)13.7% (57) 13.2% (69)8.9% (37) 8.0% (42)5.3% (22) 3.3% (17)5.1% (21) 6.1% (32)3.6% (15) 6.7% (35)2.9% (12) 1.0% (5) X2.7% (11) 2.5% (13)2.2% (9) 3.6% (19)2.2% (9) 3.3% (17)2.2% (9) 1.5% (8) X1.9% (8) 1.7% (9) X1.9% (8) 1.1% (6) X1.7% (7) 2.9% (15)1.7% (7) 0.2% (1) X1.2% (5) 1.5% (8) X1.2% (5) 1.0% (5) X1.0% (4) 4.0% (21)0.7% (3) 4.0% (21)0.7% (3) 2.5% (13)0.7% (3) 2.1% (11) X0.7% (3) 1.0% (5) X0.7% (3) 0.4% (2) X0.0% (0) 1.0% (5) X0.0% (0) 1.0% (5) X0.0% (0) 0.2% (1) X





AerialApplication‐OtherMaintenance/TestflightPassenger/Cargo(Non‐Commercial)AerialObservation‐Photography/Filming

Positioning/RTBAerialApplication‐Spraying/DisbursingInstructional/Training(Solo)Passenger/Cargo(Commercial)ExternalLoad‐Line


JHIMDAT(CY09‐11):415AccidentsActivity

Instructional/Training(Dual)Personal/Private

AerialObservation‐Fish/GameSpottingAnimalControl/HuntingEmergencyMedicalServicesAirTourAerialObservation‐OtherInstructional/Training(Evaluation)ExternalLoad‐OtherFerryInstructional/TrainingAerialObservation‐LawEnforcement

AerialObservation‐Traffic

SightseeingUtilitiesPatrolSARAerialObservation‐PropertyElectronicNewsGathering

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IndustryandActivityPairsThecombinationoftheIndustrycategoryforeachaccidentandtheActivitycategoryforeachaccidentcanbepairedtogethertorefinetheunderstandingoftheaccidentsthathappened.Thispairingresultedinninety‐sevenIndustryandActivitycombinationsthatwereusedintheJHIMDATandJHSATanalysis.Table3liststheIndustryandActivitypairsfromtheJHIMDATdataalongsidetherespectivepercentagesfromtheJHSATdata.TheIndustryandActivitypairsarelistedindescendingorderoffrequencybasedontheJHIMDATcolumn.

TheteamaccomplishedtwoseparatechisquaredanalysesasrelatedtoIndustryandActivitypairs.

1) WeanalyzedtheaggregategroupofJHIMDATaccidentsascategorizedbyIndustryandActivitypairsagainsttheaggregategroupofJHSATaccidentscategorizedbyIndustryandActivitypairs.Theconclusionwasthetwodatasetswerestatisticallydifferent.AmongsomeofthemajorcontributorstothestatisticaldifferencewastheincreaseintheproportionofaccidentsinthefollowingIndustryandActivitypairs:Personal/Private–Personal/Private,Instructional/Training‐Instructional/Training(Solo),andAerialApplication–Positioning/RTB.

a. Alimitationexistedincomparingtheaggregategroups.Forcaseswheredegreesoffreedomaregreaterthan1,bestpracticefromstatisticalreferencesourcessuggestedthatnomorethan20%oftheoveralldatasetshouldhave“expected”numberofeventslessthanfive.Seventy‐fouroutofninety‐seven(76%)oftheIndustryandActivitypairshad“expected”numbersofeventslessthanfiveinthechisquaredanalysis.Tocorrectforexceedingtherecommended20%,theteamconsideredtwodifferentapproaches.

i. Inthefirstapproach,theteamconsolidatedtheseventy‐fourIndustry

andActivitypairswith“expected”numberofeventsbelowfiveeventsintoasingle“lowevent”IndustryandActivitypairforpurposesoftheaggregatechisquaredanalysis.Afterorganizingthedatainthismannerandconductingthestatisticalanalysis,theteamobservedthetwodatasetswerestatisticallydifferent.

ii. Inconsideringasecondapproach,theteamobservedthattheseventy‐

fourcategorieswith“expected”numberofeventslessthanfiveaccountedforabout24%oftheaccidentsintheJHSATdataandabout26%intheJHIMDATdata.Forpurposesofthechisquaredanalysis,theteamexcludedtheseventy‐fourcategoriesandcomparedonlytheremainingtwenty‐threecategorieswith“expected”numberofeventsgreaterthan5.Afterorganizingthedatainthismannerandconductingthestatisticalanalysis,theconclusionwasconsistentwiththefirstapproachinfindingthetwodatasetswerestatisticallydifferent.

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2) Theteamattemptedaseparate,individualanalysistocomparethedatasetsforeachof

theninety‐sevenIndustryandActivitypairs.However,anaccurateindividualanalysiswasonlypossiblefortenoftheninety‐sevenpairs.Fortheremainingeighty‐sevenpairs,the“expected”numberofeventsfromthechisquaredanalysiswasbelowten.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableifthereislessthanten“expected”eventsforcasesof1degreeoffreedom.

Table3.IndustryandActivityPairsComparison

Activity

Personal/Private 17.8% (74) 12.0% (63)Instructional/Training(Dual) 15.2% (63) 13.6% (71)AerialApplication‐Spraying/Disbursing 8.9% (37) 8.0% (42)Instructional/Training(Solo) 4.3% (18) 2.7% (14)Positioning/RTB 4.1% (17) 5.5% (29)Positioning/RTB 3.4% (14) 1.1% (6) X

Passenger/Cargo(Commercial) 2.7% (11) 3.3% (17)Instructional/Training(Dual) 2.7% (11) 0.4% (2) XExternalLoad‐Line 2.4% (10) 2.5% (13)AerialApplication‐Other 2.4% (10) 1.0% (5) X

Passenger/Cargo(Commercial) 2.2% (9) 2.1% (11) XEmergencyMedicalServices 1.9% (8) 1.1% (6) XAerialObservation‐Fish/GameSpotting 1.9% (8) 1.0% (5) XAirTour 1.7% (7) 2.9% (15)Positioning/RTB 1.7% (7) 0.6% (3) XPassenger/Cargo(Non‐Commercial) 1.4% (6) 1.9% (10) XAerialObservation‐Photography/Filming 1.2% (5) 1.9% (10) XPositioning/RTB 1.2% (5) 1.3% (7) XAnimalControl/Hunting 1.0% (4) 1.3% (7) XInstructional/Training(Evaluation) 1.0% (4) 1.1% (6) XPositioning/RTB 1.0% (4) 0.6% (3) XInstructional/Training(Solo) 1.0% (4) 0.6% (3) XMaintenance/Testflight 1.0% (4) 0.6% (3) XPositioning/RTB 1.0% (4) 0.4% (2) XMaintenance/Testflight 1.0% (4) 0.4% (2) XAerialObservation‐Other 1.0% (4) 0.2% (1) XAnimalControl/Hunting 1.0% (4) 0.2% (1) X



Industry

Personal/PrivateInstructional/Training

Instructional/TrainingEmergencyMedicalServicesAerialApplication

Commercial

Business

LawEnforcement

Business

ExternalLoad

AerialApplication

Business

AerialObservationCommercialCommercial

Instructional/Training

Personal/Private

LawEnforcement

AerialApplication

OffshoreEmergencyMedicalServices

AerialObservationAirTour/Sightseeing

Personal/PrivateAirTour/SightseeingEmergencyMedicalServicesAerialObservation

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Activity

AerialObservation‐LawEnforcement 0.7% (3) 2.3% (12)Sightseeing 0.7% (3) 2.1% (11) XPositioning/RTB 0.7% (3) 1.7% (9) XMaintenance/Testflight 0.7% (3) 0.8% (4) XExternalLoad‐Other 0.7% (3) 0.6% (3) XAerialObservation‐Photography/Filming 0.7% (3) 0.2% (1) XAerialObservation‐Other 0.7% (3) 0.0% (0) XInstructional/Training(Dual) 0.7% (3) 0.0% (0) XExternalLoad‐Line 0.5% (2) 2.5% (13)Ferry 0.5% (2) 2.1% (11) XUtilitiesPatrol 0.5% (2) 1.0% (5) XExternalLoad‐Other 0.5% (2) 0.4% (2) XPositioning/RTB 0.5% (2) 0.2% (1) XAerialApplication‐Other 0.5% (2) 0.0% (0) XExternalLoad‐Line 0.5% (2) 0.0% (0) XSAR 0.5% (2) 0.0% (0) XInstructional/Training(Dual) 0.5% (2) 0.0% (0) XInstructional/Training 0.2% (1) 1.7% (9) XInstructional/Training 0.2% (1) 1.0% (5) XPassenger/Cargo(Non‐Commercial) 0.2% (1) 0.6% (3) XPositioning/RTB 0.2% (1) 0.6% (3) XInstructional/Training 0.2% (1) 0.6% (3) XPassenger/Cargo(Non‐Commercial) 0.2% (1) 0.4% (2) XFerry 0.2% (1) 0.4% (2) X

Passenger/Cargo(Commercial) 0.2% (1) 0.2% (1) XAerialObservation‐Photography/Filming 0.2% (1) 0.2% (1) XAerialObservation‐Fish/GameSpotting 0.2% (1) 0.2% (1) XSAR 0.2% (1) 0.2% (1) XExternalLoad‐Line 0.2% (1) 0.2% (1) XPassenger/Cargo(Non‐Commercial) 0.2% (1) 0.2% (1) XFerry 0.2% (1) 0.0% (0) XInstructional/Training(Dual) 0.2% (1) 0.0% (0) XInstructional/Training(Evaluation) 0.2% (1) 0.0% (0) XUtilitiesPatrol 0.2% (1) 0.0% (0) XExternalLoad‐Line 0.0% (0) 1.5% (8) XElectronicNewsGathering 0.0% (0) 1.0% (5) XAerialObservation‐Photography/Filming 0.0% (0) 1.0% (5) XFerry 0.0% (0) 0.8% (4) X

ElectronicNewsGathering

EmergencyMedicalServices

Commercial

LawEnforcement

Firefighting

Commercial

OffshoreBusinessUtilitiesPatrol/Construction

AerialApplicationEmergencyMedicalServices

LawEnforcementAirTour/Sightseeing

LawEnforcementCommercial

Personal/Private

FirefightingElectronicNewsGatheringCommercial

LoggingPersonal/PrivateUtilitiesPatrol/Construction

UtilitiesPatrol/ConstructionCommercialUtilitiesPatrol/Construction

AerialApplicationPersonal/Private

AirTour/SightseeingCommercialFirefighting

Personal/Private

LawEnforcement

UtilitiesPatrol/Construction

Business

LawEnforcementFirefightingCommercial

Business

IndustryJHIMDAT(CY09‐11):

415AccidentsJHSAT(CY00‐01,06):

523Accidents

14

Activity

Passenger/Cargo(Non‐Commercial) 0.0% (0) 0.4% (2) XInstructional/Training 0.0% (0) 0.4% (2) XPositioning/RTB 0.0% (0) 0.4% (2) XFerry 0.0% (0) 0.4% (2) XAerialObservation‐Property 0.0% (0) 0.4% (2) XAerialObservation‐Property 0.0% (0) 0.4% (2) XPositioning/RTB 0.0% (0) 0.4% (2) XPersonal/Private 0.0% (0) 0.2% (1) X

Passenger/Cargo(Commercial) 0.0% (0) 0.2% (1) XAerialObservation‐Traffic 0.0% (0) 0.2% (1) XPositioning/RTB 0.0% (0) 0.2% (1) XMaintenance/Testflight 0.0% (0) 0.2% (1) XInstructional/Training 0.0% (0) 0.2% (1) XAerialObservation‐Property 0.0% (0) 0.2% (1) XAerialObservation‐Fish/GameSpotting 0.0% (0) 0.2% (1) XFerry 0.0% (0) 0.2% (1) XPassenger/Cargo(Non‐Commercial) 0.0% (0) 0.2% (1) XInstructional/Training 0.0% (0) 0.2% (1) XAerialObservation‐Fish/GameSpotting 0.0% (0) 0.2% (1) XAerialObservation‐LawEnforcement 0.0% (0) 0.2% (1) XPersonal/Private 0.0% (0) 0.2% (1) XAnimalControl/Hunting 0.0% (0) 0.2% (1) X

Passenger/Cargo(Commercial) 0.0% (0) 0.2% (1) XMaintenance/Testflight 0.0% (0) 0.2% (1) XInstructional/Training(Evaluation) 0.0% (0) 0.2% (1) XMaintenance/Testflight 0.0% (0) 0.2% (1) X

Passenger/Cargo(Commercial) 0.0% (0) 0.2% (1) XPositioning/RTB 0.0% (0) 0.2% (1) XInstructional/Training(Evaluation) 0.0% (0) 0.2% (1) XMaintenance/Testflight 0.0% (0) 0.2% (1) XSAR 0.0% (0) 0.2% (1) XFerry 0.0% (0) 0.2% (1) X





ExternalLoad

Personal/Private

UtilitiesPatrol/Construction

AerialObservation

LawEnforcement

AerialObservationAirTour/SightseeingAirTour/Sightseeing

OffshoreEmergencyMedicalServicesPersonal/Private

AerialObservationPersonal/Private

IndustryJHIMDAT(CY09‐11):

415AccidentsJHSAT(CY00‐01,06):

523Accidents

CommercialElectronicNewsGatheringBusinessFirefighting

Instructional/Training

FirefightingFirefighting

LawEnforcementLawEnforcement

LawEnforcement

Business

Business

LoggingAerialApplication

Personal/Private

Personal/Private

FirefightingAerialObservation

AirTour/Sightseeing

15

OccurrenceCategoryOccurrenceCategoriesprovidedaconcisedescriptionof“whathappened”inanaccident.Table4liststheOccurrenceCategoriesfromtheJHIMDATdataalongsidetherespectivepercentagesfromJHSATdata.ThetablelistseighteenOccurrenceCategoriesindescendingorderoffrequencybasedontheJHIMDATcolumn.

AchisquaredanalysisthatcomparedtheaggregategroupofJHIMDATtoJHSATaccidentsbyOccurrenceCategorieswasnotpossibleusingthesameformatastheIndustryandActivitydata.ThisisbecauseeachaccidentwasnotlimitedtoassignmentinasingleOccurrenceCategory.BoththeJHSATandJHIMDATmethodologyallowedeachindividualaccidenttobecodedwithuptofourdifferentOccurrenceCategories.ThisaspectofthemethodologyexplainswhythepercentagesofOccurrenceCategoriesfromeachdatasetshouldnotbesummedwiththeexpectationoftheresulttotaling100%.MultipleOccurrenceCategoriesperaccidentensuredthesummedtotalwillfarexceed100%.

However,theteamdidattemptaseparate,individualanalysistocomparethedatasetsforeachoftheeighteenOccurrenceCategories.ThiswaspossiblebygroupingallaccidentswhereanOccurrenceCategoryhadbeenusedatleastonceintoonesetofdata(e.g.,allLossofControlaccidents),whilegroupingallaccidentswherethatsameOccurrenceCategorywasneverusedintoanothersetofdata(e.g.,allaccidentswhereLossofControlwasnotcited).AsshowninTable4,LossofControlandControlledFlightIntoTerrain(CFIT)showedstatisticallysignificantincreaseswhileSystemsComponentFailure(SCF),LandingZone(LZ),andExternalLoad(EXTL)showedstatisticallysignificantdecreases.

AnaccurateindividualanalysiswasonlypossibleforfourteenoftheeighteenOccurrenceCategories.Fortheremainingfourcategories,the“expected”numberofeventsfromthechisquaredanalysiswasbelowten.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthanten“expected”eventsforcasesof1degreeoffreedom.

TheteamdecidedfurtherexplanationwasneededfortheAbnormalRunwayContact(ARC)OccurrenceCategoryshowninTable4.Although(ARC)hadsufficient“expected”eventsforanaccuratechisquaredanalysis,theJHIMDATexcludeditalongwiththefourpreviouslymentionedcategories.ThedecisionmayappearpuzzlinginthattheteamassignedARCto24.6%oftheaccidentsintheJHIMDATdataascomparedto7.6%oftheaccidentsintheJHSATdata.ItwouldappeartheOccurrenceCategoryisaclearcandidateforassessingwhetherasignificantstatisticaldifferenceexisted.However,theJHIMDATexcludedthiscategorybecauseweattributedtherelativelylargedifferenceinproportionstoadifferentunderstandingandassignmentoftheARCcategoryintheJHIMDATanalysisasopposedtohowitwaspreviouslyusedintheJHSATanalysis.TheJHIMDATdidnotthinktherewasanactualincreaseinthecasesofARC;rather,therewasadifferentapplicationoftheOccurrenceCategorybytheJHIMDAT.ThisledtoinconsistencyinhowitwasassignedintheJHIMDATdatawhencomparedtotheearlierJHSATwork.

16

Table4.OccurrenceCategoryComparison

47.5% (197) 41.5% (217)32.8% (136) 31.7% (166)24.6% (102) 7.6% (40) X21.4% (89) 27.5% (144)19.8% (82) 16.4% (86)8.2% (34) 7.6% (40)8.0% (33) 10.7% (56)7.0% (29) 6.1% (32)6.7% (28) 3.1% (16)3.9% (16) 2.3% (12) X3.9% (16) 1.3% (7) X3.6% (15) 4.0% (21)3.1% (13) 7.5% (39)3.1% (13) 6.5% (34)2.7% (11) 2.3% (12) X2.7% (11) 0.4% (2)1.4% (6) 4.8% (25)0.2% (1) 1.3% (7) X





CFIT‐ControlledFlightintoTerrain



OccurrenceCategory

LOC‐LossofControlAUTO‐AutorotationARC‐AbnormalRunwayContactSCF‐SystemComponentFailureSTRIKEFUELVIS‐VisibilityFIRE

DITCH‐DitchingWSTRW‐Windshear/ThunderstormEXTL‐ExternalLoadICE‐Icing

ADRM‐AirportRAMPAMAN‐AbruptManueverLZ‐LandingZoneUNK‐Unknown/Other

17

FatalandNon‐FatalAccidentProportionsbyOccurrenceCategoryTables5through12comparetheproportionoffatalandnon‐fatalaccidentsbetweentheJHIMDATandJHSATdataforaselectedlistofOccurrenceCategories.TheteamselectedtheeightmostfrequentlycitedOccurrenceCategoriesfromtheJHIMDATdata(seeTable4).Forreasonsnotedearlierinthereport,theteamdidnotincludeAbnormalRunwayContactasoneoftheeightselectedOccurrenceCategories.Foreachselectedoccurrencecategory,theJHIMDATusedachisquaredanalysistodeterminewhethertherewasastatisticaldifferencebetweenthenumberoffatalandnon‐fatalaccidentsintheJHIMDATdataascomparedtothenumberoffatalandnon‐fatalaccidentsintheJHSATdata.AnaccuratechisquaredanalysiswasnotpossiblefortwooftheselectedOccurrenceCategories:AutorotationandFuel.Inthesetwocases,the“expected”numberofeventsfromthechisquaredanalysiswasbelowten.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthanten“expected”eventsforcasesof1degreeoffreedom.

Foreachofthesixoccurrencecategorieswhereareliablechisquaredanalysiswaspossible,therewasnotastatisticaldifferencebetweentheJHIMDATdataandtheJHSATdata.

Table5.Fatal/Non‐FatalLossofControl(LOC)

InjuryOutcome

Non‐Fatal 88.8% (175) 87.1% (189)Fatal 11.2% (22) 12.9% (28)

JHIMDAT(CY09‐11):197LOCAccidents

JHSAT(CY00‐01,06):217LOCAccidents

Table6.Fatal/Non‐FatalAutorotation(AUTO)

InjuryOutcome

Non‐Fatal 95.6% (130) 94.6% (157)Fatal 4.4% (6) 5.4% (9)

JHIMDAT(CY09‐11):136AUTOAccidents

JHSAT(CY00‐01,06):166AUTOAccidents

Table7.Fatal/Non‐FatalSystemComponentFailure(SCF)

InjuryOutcome

Non‐Fatal 93.3% (83) 88.2% (127)Fatal 6.7% (6) 11.8% (17)

JHIMDAT(CY09‐11):89SCFAccidents

JHSAT(CY00‐01,06):144SCFAccidents

Table8.Fatal/Non‐FatalStrike

InjuryOutcome

Non‐Fatal 82.9% (68) 76.7% (66)Fatal 17.1% (14) 23.3% (20)

JHIMDAT(CY09‐11):82StrikeAccidents

JHSAT(CY00‐01,06):86StrikeAccidents

18

Table9.Fatal/Non‐FatalFuelIssue

InjuryOutcome

Non‐Fatal 85.3% (29) 90.0% (36)Fatal 14.7% (5) 10.0% (4)

JHIMDAT(CY09‐11):34FuelAccidents

JHSAT(CY00‐01,06):40FuelAccidents

Table10.Fatal/Non‐FatalVisibility(VIS)Issue

InjuryOutcome

Non‐Fatal 45.5% (15) 60.7% (34)Fatal 54.5% (18) 39.3% (22)

JHIMDAT(CY09‐11):33VISAccidents

JHSAT(CY00‐01,06):56VISAccidents

Table11.Fatal/Non‐FatalFire

InjuryOutcome

Non‐Fatal 41.4% (12) 37.5% (12)Fatal 58.6% (17) 62.5% (20)

JHIMDAT(CY09‐11):29FireAccidents

JHSAT(CY00‐01,06):32FireAccidents

Table12.Fatal/Non‐FatalControlledFlightIntoTerrain(CFIT)

InjuryOutcome

Non‐Fatal 42.9% (12) 56.3% (9)Fatal 57.1% (16) 43.8% (7)

JHIMDAT(CY09‐11):28CFITAccidents

JHSAT(CY00‐01,06):16CFITAccidents

19

OccurrenceCategory’sInfluenceonFatal&Non‐FatalAccidentsTheJHIMDATanalyzedwhetherthepresenceorabsenceofaselectedOccurrenceCategoryresultedinanystatisticaldifferenceregardingtheproportionoffatalandnon‐fatalaccidents.TheteamusedthesameeightOccurrenceCategoriesshowninTables5through12.However,thechisquaredanalysiswasdifferentfromprevioussectionsinthatitconsistedoftwodimensions.TheOccurrenceCategory(eitherpresentorabsent)wasonedimensionandtheinjuryoutcome(eitherfatalornon‐fatal)wastheseconddimension.Becauseofthetwodimensions,theteamusedachisquaredtestofhomogeneity(ratherthanachisquaredgoodnessoffit)forthecomparison.Thetestofhomogeneityhadtobeconductedindependentlyoneachdataset,meaningthattheJHIMDATdataandJHSATdatawerenotcomparedtoeachotherwithinthesametest.However,oncethetestwasseparatelycompletedoneachrespectivedataset,theteamcouldthendetermineiftheresultsofthetestofhomogeneityhadchangedfromtheJHSATdatatotheJHIMDATdata.Toinitiatetheanalysis,theJHIMDATfirstcategorizedeachaccidentintheJHSATdataintotwogroups.ThefirstgroupwasallaccidentswheretheOccurrenceCategoryunderstudywaspresent,whilethesecondgroupwasallaccidentswhereitwasnot.Afterthisinitialgrouping,theteamfurtherdividedtheJHSATdataintofatalaccidentsandnon‐fatalaccidents.OncetheteamcompletedthisdivisionofdataforeachoftheOccurrenceCategoriesunderstudyintheJHSATdata,wealsousedthesamemethodofcategorizationfortheJHIMDATdata.ForallbutoneOccurrenceCategory,thestatisticalconclusionreachedfromthechisquaredtestofhomogeneitywasthesamewhenresultsfromtheJHIMDATdatawerecomparedtoresultsfromtheJHSATdata.Theproportionsoffatalandnon‐fatalaccidentsforeachOccurrenceCategorystudiedfromtheJHIMDATandJHSATdataareshowninTables13through20.TheoneOccurrenceCategorywheretheteamnoteddifferentresultsbetweentheJHIMDATdataandtheJHSATdatawasSystemComponentFailure(SCF).FortheJHIMDATdata,theteamnotedastatisticallysignificantdifferencebetweenSCFandNoSCFaccidentsregardingtheproportionoffatalandnon‐fatalaccidents.ThisstatisticaldifferencewasnotevidentintheJHSATdata.Tobeclear,intheJHSATdatathesametrendswerenotedintheSCFproportionsoffatalandnon‐fatalaccidentsaswereevidentintheJHIMDATdata;however,intheJHSATdatathedifferencesdidnotrisetoalevelthatconstitutedstatisticalsignificanceusingp=.01.

20

Table13.LossofControl(LOC)OccurredComparedtoNoLOCOccurredJHIMDAT(CY09‐11)Data* NotFatal FatalLOCOccurred 88.8% (175/197) 11.2% (22/197)NoLOCOccurred 79.8% (174/218) 20.2% (44/218) JHSAT(CY00‐01,06)Data NotFatal FatalLOCOccurred 87.1% (189/217) 12.9% (28/217)NoLOCOccurred 81.0% (248/306) 19.0% (58/306)Conclusion:TherewasnostatisticaldifferencebetweenLOCandnon‐LOCaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).*Note:FortheJHIMDATdata,theconclusionthattherewasalackofstatisticaldifferencewasbasedonacalculatedpvalue(0.012)thatwasgreaterthanthepvalueusedasthestandardfordeterminingstatisticalsignificancethroughoutthisreport(0.01).Asevident,however,thedifferencebetweenthetwopvalueswasrelativelysmall(.002).Theteamthoughtitworthsharingthisobservationandnotingthathadalarger(butstillacceptable)pvalue(suchas0.02or0.05)beenused,therewouldbeastatisticaldifferencebetweentheLOCandnon‐LOCaccidentsregardingtheproportionoffatalandnon‐fatalaccidentsintheJHIMDATdata.Table14.Autorotation(AUTO)OccurredComparedtoNoAUTOOccurredJHIMDAT(CY09‐11)Data NotFatal FatalAUTOOccurred 95.6% (130/136) 4.4% (6/136)NoAUTOOccurred 78.5% (219/279) 21.5% (60/279) JHSAT(CY00‐01,06)Data NotFatal FatalAUTOOccurred 94.6% (157/166) 5.4% (9/166)NoAUTOOccurred 78.4% (280/357) 21.6% (77/357)Conclusion:TherewasastatisticaldifferencebetweenAUTOandnon‐AUTOaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).

Majorstatisticalcontributor(s)todifference:1)AccidentswhereanAUTOoccurredhadfewerfataloutcomesthanstatisticallyexpected.2)AccidentswherenoAUTOoccurredhadmorefataloutcomesthanstatisticallyexpected.

21

Table15.SystemComponentFailure(SCF)OccurredComparedtoNoSCFOccurredJHIMDAT(CY09‐11)Data NotFatal FatalSCFOccurred 93.3% (83/89) 6.7% (6/89)NoSCFOccurred 81.6% (266/326) 18.4% (60/326) JHSAT(CY00‐01,06)Data NotFatal FatalSCFOccurred 88.2% (127/144) 11.8% (17/144)NoSCFOccurred 81.8% (310/379) 18.2% (69/379)Conclusion:TherewasastatisticaldifferencebetweenSCFandnon‐SCFaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliesonlytoJHIMDATdataasnostatisticaldifferencewasfoundinJHSATdata).

Majorstatisticalcontributor(s)todifference:AccidentswhereaSCFoccurredhadfewerfataloutcomesthanstatisticallyexpected(appliesonlytoJHIMDATdata).Table16.StrikeOccurredComparedtoNoStrikeOccurredJHIMDAT(CY09‐11)Data NotFatal FatalStrikeOccurred 82.9% (68/82) 17.1% (14/82)NoStrikeOccurred 84.4% (281/333) 15.6% (52/333) JHSAT(CY00‐01,06)Data NotFatal FatalStrikeOccurred 76.7% (66/86) 23.3% (20/86)NoStrikeOccurred 84.9% (371/437) 15.1% (66/437)Conclusion:TherewasnostatisticaldifferencebetweenStrikeandnon‐Strikeaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).Table17.FuelIssueOccurredComparedtoNoFuelIssueOccurredJHIMDAT(CY09‐11)Data NotFatal FatalFuelIssueOccurred 85.3% (29/34) 14.7% (5/34)NoFuelIssueOccurred 84.0% (320/381) 16.0% (61/381) JHSAT(CY00‐01,06)Data NotFatal FatalFuelIssueOccurred 90.0% (36/40) 10.0% (4/40)NoFuelIssueOccurred 83.0% (401/483) 17.0% (82/483)Conclusion:TherewasnostatisticaldifferencebetweenFuelissueandnon‐Fuelissueaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).

22

Table18.Visibility(VIS)IssueOccurredComparedtoNoVISIssueOccurredJHIMDAT(CY09‐11)Data NotFatal FatalVISIssueOccurred 45.5% (15/33) 54.5% (18/33)NoVISIssueOccurred 87.4% (334/382) 12.6% (48/382) JHSAT(CY00‐01,06)Data NotFatal FatalVISIssueOccurred 60.7% (34/56) 39.3% (22/56)NoVISIssueOccurred 88.9% (415/467) 11.1% (52/467)Conclusion:TherewasastatisticaldifferencebetweenVISIssueandnon‐VISIssueaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).

Majorstatisticalcontributor(s)todifference:AccidentswhereaVISIssueoccurredhadmorefataloutcomesandfewernon‐fataloutcomesthanstatisticallyexpected(JHIMDATdataandJHSATdata).AccidentswhereaVISIssueoccurredhadfewernon‐fataloutcomesthanstatisticallyexpected(JHIMDATdataonly).

Table19.FireOccurredComparedtoNoFireOccurredJHIMDAT(CY09‐11)Data NotFatal FatalFireOccurred 41.4% (12/29) 58.6% (17/29)NoFireOccurred 87.3% (337/386) 12.7% (49/386) JHSAT(CY00‐01,06)Data NotFatal FatalFireOccurred 37.5% (12/32) 62.5% (20/32)NoFireOccurred 86.6% (425/491) 13.4% (66/491)Conclusion:TherewasastatisticaldifferencebetweenFireandnon‐Fireaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).

Majorstatisticalcontributor(s)todifference:AccidentswhereaFireoccurredhadmorefataloutcomesandfewernon‐fataloutcomesthanstatisticallyexpected(JHIMDATdataandJHSATdata).

23

Table20.CFITOccurredComparedtoNoCFITOccurredJHIMDAT(CY09‐11)Data NotFatal FatalCFITOccurred 42.9% (12/28) 57.1% (16/28)NoCFITOccurred 87.1% (337/387) 12.9% (50/387) JHSAT(CY00‐01,06)Data NotFatal FatalCFITOccurred 56.3% (9/16) 43.8% (7/16)NoCFITOccurred 84.4% (428/507) 15.6% (79/507)Conclusion:TherewasastatisticaldifferencebetweenCFITandnon‐CFITaccidentsregardingtheproportionoffatalandnon‐fatalaccidents(appliestoindependentanalysisofbothJHIMDATdataandJHSATdata).

Majorstatisticalcontributor(s)todifference:AccidentswhereCFIToccurredhadmorefataloutcomesthanstatisticallyexpected(JHIMDATdataandJHSATdata).AccidentswhereCFIToccurredhadlessnon‐fatalaccidentsthanstatisticallyexpected(JHIMDATdataonly).

24

Sub‐OccurrenceCategoryTheSub‐OccurrenceCategoryservedthepurposeofprovidingamoredetaileddescriptionwithineachOccurrenceCategory.Table21liststhe50OccurrenceCategory/Sub‐OccurrenceCategorypairsfromtheJHIMDATdataalongsidetherespectivepercentagesfromJHSATdata.ThetableliststhepairsindescendingorderoffrequencybasedontheJHIMDATcolumn.

ForthesamereasonsnotedintheOccurrenceCategoryportionofthereport,achisquaredanalysisthatcomparedtheaggregategroupofJHIMDATtoJHSATaccidentsbyOccurrenceCategory/Sub‐Occurrencepairswasnotpossible.

However,theteamdidattemptaseparate,individualanalysistocomparethedatasetsforeachofthe50OccurrenceCategory/Sub‐OccurrenceCategorypairs.Thiswaspossiblebygroupingallaccidentswhereapairinghadbeenusedatleastonceintoonesetofdata(e.g.,allLossofControl–PerformanceManagement),whilegroupingallaccidentswherethatsamepairingwasneverusedintoanothersetofdata(e.g.,allaccidentswhereLossofControl–PerformanceManagementwasnotcited).TheresultsareshowninTable21.

Anaccurateindividualanalysiswasonlypossiblefor23ofthe50OccurrenceCategory/Sub‐OccurrenceCategorypairs.Fortheremaining27pairs,the“expected”numberofeventsfromthechisquaredanalysiswasbelowten.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthanten“expected”eventsforcasesof1degreeoffreedom.

TherewerestatisticaldifferencesfoundbetweentheJHIMDATandJHSATdatafortheninepairs:

AccidentsIncreased: 1)LossofControl–PerformanceManagement2)Strike‐LowAltitudeMission3)Strike‐TakeoffandLanding4)CFIT‐CFIT

AccidentsDecreased:1)SystemComponentFailure–Helicopter

2)LandingZone–Unprepared3)Strike–ObjectStrike4)Unknown/Other–Regulatory5)ExternalLoad–ExternalLoad

Therewerenotstatisticaldifferencesfoundfortheother14pairswhereachisquaredanalysiswaspossible.Forthesecases,anydifferencesbetweentheJHIMDATdataandtheJHSATdatawereattributedtorandomfluctuations.AsalsonotedintheOccurrenceCategorysectionofthereport,theteamdidnotanalyzetheOccurrenceCategory/Sub‐OccurrenceCategorypairofAbnormalRunwayContact(ARC)forastatisticaldifference.Theexplanationisthesameaspreviouslynoted.TheteamdidnotthinktherewasanactualincreaseinthecasesofARC;rather,therewasadifferentapplicationoftheOccurrenceCategorybytheJHIMDATandthisledtoinconsistencyinhowitwasassignedbytheJHIMDATwhencomparedtotheearlierJHSATwork.

25

Table21.Sub‐OccurrenceCategoryComparison

24.6% (102) 7.6% (40) X22.9% (95) 21.8% (114)21.7% (90) 15.1% (79)11.8% (49) 10.9% (57)8.7% (36) 5.5% (29)8.7% (36) 4.0% (21)8.4% (35) 5.9% (31)8.0% (33) 10.1% (53)7.5% (31) 14.3% (75)6.7% (28) 3.1% (16)6.0% (25) 5.2% (27)5.8% (24) 2.5% (13) X4.3% (18) 5.2% (27)3.9% (16) 1.3% (7) X3.6% (15) 5.0% (26)3.6% (15) 4.0% (21)3.4% (14) 3.4% (18)3.4% (14) 2.9% (15)3.1% (13) 3.3% (17)2.9% (12) 4.4% (23)2.9% (12) 2.1% (11) X2.7% (11) 6.9% (36)2.7% (11) 4.4% (23)2.7% (11) 2.3% (12) X2.4% (10) 7.3% (38)2.2% (9) 0.6% (3) X1.9% (8) 4.2% (22)1.7% (7) 0.8% (4) X1.7% (7) 0.2% (1) X1.4% (6) 5.7% (30)1.4% (6) 4.8% (25)1.4% (6) 1.1% (6) X1.4% (6) 1.1% (6) X1.4% (6) 0.4% (2) X1.4% (6) 0.2% (1) X1.2% (5) 0.0% (0) X1.0% (4) 1.0% (5) X



OccurrenceCategory/Sub‐OccurrenceCategory

AbnormalRwyContact‐AbnormalRwyContact

Autorotation‐Practice

Autorotation‐EmergencyLossofControl‐PerformanceManagement

Strike‐LowAltitudeMissionStrike‐TakeofforLanding

LossofControl‐Unknown

LossofControl‐DynamicRolloverSystemComponentFailure‐EngineSystemComponentFailure‐HelicopterCFIT‐CFITFire‐PostImpactSystemComponentFailure‐Unconfirmed/PerceivedLossofControl‐ExceedingOperatingLimitsRamp‐RampVisibility‐InadvertentIMCAbruptManeuver‐AbruptManeuverFuel‐Exhaustion

Unknown/Other‐Regulatory

LossofControl‐InterferencewithControlsLossofControl‐LossofT/RAuthorityFuel‐StarvationLandingZone‐UnpreparedLossofControl‐EmergencyProceduresDitching‐DitchingStrike‐ObjectStrikeLossofControl‐Settlingw/powerVisibility‐Night/DarknessUnknown/Other‐OtherWindshear/Thunderstorm‐Windshear

ExternalLoad‐ExternalLoadAirport‐MobileHelipadFuel‐CarbIceVisibility‐Sun/GlareAirport‐PlatformLossofControl‐UnattendedAircraftFire‐NonImpact

26

Table21.Sub‐OccurrenceCategoryComparison(continued)1.0% (4) 0.2% (1) X0.7% (3) 1.0% (5) X0.7% (3) 0.8% (4) X0.5% (2) 1.5% (8) X0.5% (2) 1.3% (7) X0.5% (2) 1.0% (5) X0.5% (2) 1.0% (5) X0.5% (2) 0.6% (3) X0.5% (2) 0.6% (3) X0.5% (2) 0.4% (2) X0.2% (1) 1.3% (7) X0.2% (1) 1.1% (6) X0.0% (0) 0.2% (1) X





Visibility‐FlatLight

Windshear/Thunderstorm‐ThunderstormLossofControl‐GroundResonanceLossofControl‐Tie‐downs/hosesVisibility‐White‐out/Brown‐out

Visibility‐Fog/GlareVisibility‐GlassyWater

Fuel‐ContaminationSystemComponentFailure‐MissionEquipmentAirport‐Heliport/AirportLandingZone‐PreparedAirport‐FixedHelipadIcing‐Icing

27

JointAircraftSystem/Component(JASC)CodesTheoriginalJHSATdatadelineatedSystemComponentFailure(SCF)accidentsintooneoffourcategories:1)Engine,2)Helicopter,3)MissionEquipment,or4)Unconfirmed/Perceived.TheJHIMDATsoughttoexpandonthespecificityassociatedwithSCFaccidentanalysisthroughuseofJASCcodes.TheteamincludedaJASCCodeanalysisforthe89SCFaccidentsfromtheJHIMDATdata(comprising21.4%ofthe415totalaccidents)andthenreturnedtotheoriginalJHSATdataanddidlikewiseforthe144SCFaccidents(comprising27.5%ofthe523totalaccidents).Theteamusedthirty‐ninedifferentfourdigitJASCCodesintheJHIMDATdataandfifty‐sixdifferentfourdigitJASCCodesintheJHSATdata.

BecauseofthemanydifferentJASCCodesusedbetweenthetwodatasets,theteamhadtoconsolidatethemtoallowforanaccuratestatisticalcomparisonbetweentheJHIMDATandtheJHSATdata.Forthispurpose,wesortedthevarietyofJASCCodesintothreegeneralcategories.Table22liststheconsolidatedJASCCodecategoriesfromtheJHIMDATdataalongsidetherespectivepercentagesfromtheJHSATdata.TheJASCCodesarelistedindescendingorderoffrequencybasedontheJHIMDATcolumn.

ThereweretwoseparatechisquaredanalysesaccomplishedasrelatedtoJASCCode.

1) TheteamanalyzedtheaggregategroupofJHIMDATaccidentsascategorizedbyJASCCodeagainsttheaggregategroupofJHSATaccidentscategorizedbyJASCCode.Theconclusionwasthetwodatasetswerenotstatisticallydifferent.

2) Theteamconductedaseparate,individualanalysisforeachoftheJASCCodecategoriesinTable22.EachoftheconsolidatedcategorieswascomparedtoallaccidentswherethatconsolidatedcategoryofJASCCodeswasnotused.AsshowninTable22,therewasnotastatisticallysignificantdifferencebetweentheJHSATdataandtheJHIMDATdataforanyofthethreecategories.

Table22.ComparisonofConsolidatedJASCCodes

55.1% (49) 45.8% (66)29.2% (26) 38.2% (55)15.7% (14) 16.0% (23)

DenotesnostatisticallysignificantchangeinproportionofaccidentsfromJHSATdatatoJHIMDATdata

PowerplantSystems(7000,8000series)

RotorSystems(6000series)

AirframeSystems(2000,3000,4000,5000series)

JHIMDAT(CY09‐11):89SCFAccidents


JASCDescription

DenotesstatisticallysignificantincreaseinproportionofaccidentsfromJHSATdatatoJHIMDATdata

DenotesstatisticallysignificantdecreaseinproportionofaccidentsfromJHSATdatatoJHIMDATdata

28

Table23hasamoredetailedlistoftheJASCcodesusingthefirsttwodigitsoftheJASCcodetogroupthedata.ThetableisorganizedindescendingorderoffrequencybasedontheJHIMDATcolumn.AfterorganizingthedataintotwodigitJASCcodes,theteamattemptedanaggregatechisquaredanalysisbutfoundanaccuratestatisticalanalysiswasnotpossible.Wefoundthat70%ofthecategoriesinthedatasethad“expected”eventslessthanfive.Forcaseswheredegreesoffreedomaregreaterthan1,bestpracticefromstatisticalreferencesourcessuggestedthatnomorethan20%oftheoveralldatasetshouldhave“expected”numberofeventslessthanfive.Likewise,anindividualchisquaredanalysiswasattemptedforeachindividualtwodigitJASCcategorybutalsocouldnotbeperformedaccurately.Theindividualanalysisfoundthatonlyoneofthetwenty‐threecategorieshadgreaterthanten“expected”events.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthanten“expected”eventsforcasesof1degreeoffreedom.

Despitethelimitationsnoted,Table23canstillbeusedtoassessthefrequencythatvarioustwodigitJASCcodesoccurinrelationtoeachother.

Table23. JASCCodesbyMajorSystemIdentifier(First2Digits)JASC Description7200 Turbine/TurbopropEngine 24.7% (22) 18.1% (26)8500 ReciprocatingEngine 13.5% (12) 8.3% (12)7300 EngineFuelandControl 12.4% (11) 9.7% (14)6300 MainRotorDrive 10.1% (9) 9.7% (14)6200 MainRotor 7.9% (7) 4.2% (6)6700 RotorsFlightControl 6.7% (6) 7.6% (11)2800 Fuel 5.6% (5) 2.1% (3)2900 HydraulicPower 3.4% (3) 2.8% (4)5300 Fuselage 3.4% (3) 2.8% (4)6500 TailRotorDrive 3.4% (3) 9.7% (14)3200 LandingGear 2.2% (2) 0.7% (1)7400 Ignition 2.2% (2) 0.7% (1)2500 Equipment/Furnishings 1.1% (1) 4.2% (6)6400 TailRotor 1.1% (1) 6.9% (10)7100 Powerplant 1.1% (1) 4.9% (7)7600 EngineControls 1.1% (1) 1.4% (2)2100 AirConditioning 0.0% (0) 0.7% (1)2400 ElectricalPower 0.0% (0) 0.7% (1)2700 FlightControls 0.0% (0) 1.4% (2)5200 Doors 0.0% (0) 0.7% (1)7700 EngineIndicating 0.0% (0) 0.7% (1)7900 EngineOil 0.0% (0) 0.7% (1)8100 Turbocharging 0.0% (0) 1.4% (2)

JHIMDAT:89SCFAccidents JHSAT:144SCFAccidents

29

InitiatorofSystemComponentFailure(SCF)TheJHIMDATobservedthateachSystemComponentFailure(SCF)hadaninitiatingevent.TheteamdesignatedthiseventastheInitiatorofSCFandfoundthatfourmajorcategoriesexisted:MaintenanceError,ManufacturingError,PilotError,orUnknown.Table25hasthefourcategoriesorganizedindescendingorderoffrequencybasedontheJHIMDATcolumn.IdenticaltotheJASCCodeanalysis,notethatthepercentagesshowninthetablearebasedonlyonthesubsetofSCFaccidents.Thisconsistedof89accidentsfromtheJHIMDATdata(21.4%ofthe415totalaccidents)and144accidentsfromtheJHSATdata(27.5%ofthe523totalaccidents).

ThereweretwoseparatechisquaredanalysesaccomplishedasrelatedtotheInitiatorofSCF.

1)TheteamanalyzedtheaggregategroupofJHIMDATaccidentscategorizedbytheInitiatorofSCFagainsttheaggregategroupofJHSATaccidentscategorizedbytheInitiatorofSCF.Theconclusionwasthetwodatasetswerestatisticallydifferent.MajorcontributorstothestatisticaldifferenceweretheincreaseintheproportionofaccidentswheretheInitiatorofSCFwasUnknownandthedecreaseintheproportionofaccidentswheretheInitiatorofSCFwasManufacturingError.

2)Theteamattemptedaseparate,individualanalysisforeachspecificInitiatorofSCFcomparingtheJHIMDATdatatotheJHSATdata.TheresultsareinTable24.Ofnote,however,isthattheteamcouldnotperformanindividualchisquaredanalysisforthePilotErrorcategory.Forthiscategory,the“expected”numberofeventsfromthechisquaredanalysiswasbelow10.Accordingtobestpracticefromstatisticalreferencesources,thechisquaredanalysisisnotconsideredreliableiftherearelessthan10“expected”eventsforcasesof1degreeoffreedom.

ThestatisticallysignificantincreaseintheUnknowncategoryoftheJHIMDATdatainhibitedtheabilitytodrawmoremeaningfulconclusionsfromtheanalysis.TheUnknowncategoryeffectivelymasksthetrueproportionsofaccidentsinthemoredescriptivecategoriesassociatedwithInitiatorofSCF.Forexample,notethattheInitiatorofSCFsattributabletoManufacturingErrorshowedastatisticallysignificantdecreasebetweendatasets.However,itispossiblethedecreasewasartificial.WedidnotknowhowmanyoftheaccidentswithintheUnknowncategorymayhaveactuallybeenattributabletoManufacturingErrorifmoreinvestigativeinformationhadbeenavailable.So,ManufacturingErrormayhaveshownatruestatisticallysignificantdecrease,orthedecreasemayhavebeenartificialifmoreManufacturingErrorcaseswerehiddenintheUnknowncategory.ThissameconditioncouldhaveaffectedtheresultsoftheMaintenanceErrorandPilotErrorcategories.

30

Table24.InitiatorofSystemComponentFailures(SCFs)

44.9% (40) 18.1% (26)40.4% (36) 50.7% (73)7.9% (7) 21.5% (31)6.7% (6) 9.8% (14) X


PilotError




ManufacturingError

IniatorofSCF JHIMDAT(CY09‐11):89SCFAccidents


UnknownMaintenanceError

31

TypeEngineInstalledTheteamgroupedaccidentsfromboththeJHIMDATdataandtheJHSATdataintooneofthreecategoriesofinstalledengineorengines:turbinetwin,turbinesingle,orreciprocating.

ThereweretwoseparatechisquaredanalysesaccomplishedasrelatedtotheInitiatorofSCF.

1) TheteamanalyzedtheaggregategroupofJHIMDATaccidentscategorizedbytheTypeEngineInstalledagainsttheaggregategroupofJHSATaccidentscategorizedbytheTypeEngineInstalled.Theconclusionwasthetwodatasetswerestatisticallydifferent.Majorcontributorstothestatisticaldifferenceweretheincreaseintheproportionofaccidentswhererotorcrafthadareciprocatingengineinstalledandthedecreaseintheproportionofaccidentswhererotorcrafthadtwinturbineenginesinstalled.

2) Theteamconductedaseparate,individualanalysisforeachcategoryofTypeEngineInstalledcomparingtheJHIMDATdatatotheJHSATdata.TheresultsareinTable25.

Table25.TypeEngineInstalledComparison

6.0% (25) 9.4% (49)

43.4% (180) 48.2% (252)50.6% (210) 42.4% (222)


EngineInstallation

TurbineTwinTurbineSingleReciprocating






32

AccidentsbyMonthTheteamgroupedaccidentsfrombothdatasetsbasedonthemonthofoccurrence.Thereweretwoseparatechisquaredanalysesaccomplishedasrelatedtotheaccidentsbymonth.

1) TheteamanalyzedtheaggregategroupofJHIMDATaccidentscategorizedbythemonthofoccurrenceagainsttheaggregategroupofJHSATaccidentscategorizedbythemonthofoccurrence.Therewasnotastatisticaldifferencebetweenthetwodatasets.

2) Theteamconductedaseparate,individualanalysisforeachmonthcomparingtheJHIMDATdatatotheJHSATdata.TheresultsareinTable26.

Theteamalsoattemptedaseparate,individualanalysisofaccidentsbymonthforeachofthefivemostfrequentlycitedIndustrycategories:1)Personal/Private,2)Instructional/Training,3)AerialApplication,4)EMS,and5)Commercial.However,anaccurateindividualanalysiswasonlypossibleforInstructional/Training.FortheremainingfourIndustrycategoriesmentioned,morethan20%ofthemonthsineachdatasethadan“expected”numberofeventslessthanfive.Forcaseswheredegreesoffreedomaregreaterthan1,bestpracticefromstatisticalreferencesourcessuggestedthatnomorethan20%oftheoveralldatasetshouldhave“expected”numberofeventslessthanfive.Instructional/TrainingshowedastatisticallysignificantdifferencefromtheJHSATdatatotheJHIMDATdata.ThemajorcontributorstothestatisticaldifferenceinInstructional/TrainingaccidentsbymonthwereanincreaseintheproportionofaccidentsinOctoberandadecreaseintheproportionofaccidentsinDecember.

33

Table26.AccidentsbyMonthComparison

5.3% (22) 6.5% (34)February 6.0% (25) 7.3% (38)March 9.2% (38) 8.6% (45)April 5.3% (22) 8.2% (43)May 9.6% (40) 12.2% (64)June 9.9% (41) 9.0% (47)July 14.9% (62) 10.5% (55)August 8.9% (37) 10.1% (53)September 11.1% (46) 8.6% (45)October 8.2% (34) 6.7% (35)November 6.7% (28) 6.3% (33)December 4.8% (20) 5.9% (31)


Month

January






34

WeatherConditionTheteamgroupedaccidentsfromboththeJHIMDATandtheJHSATaccordingtowhethertheaccidentoccurredinVisualMeteorologicalConditions(VMC)orInstrumentMeteorologicalConditions(IMC).TherewasnotastatisticallysignificantdifferenceintheproportionofVMCandIMCaccidentsbetweenthetwodatasets.Table27liststhepercentagesofaccidentscategorizedbyweatherconditionsofVMCorIMCforboththeJHIMDATandJHSATanalyses.Table27.WeatherComparison

95.9% (398) 94.5% (494)4.1% (17) 5.5% (29)





Weather JHIMDAT(CY09‐11):415Accidents JHSAT(CY00‐01,06):523Accidents

VMCIMC

35

FatalandNon‐FatalAccidentCountsbyWeatherConditionTable28showsthefrequencyoffatalandnon‐fatalaccidentsforVMCOnlyaccidentsintheJHIMDATdataascomparedtothefrequencyoffatalandnon‐fatalaccidentsforVMCOnlyaccidentsintheJHSATdata.Table29issimilarlyarranged,butprovidesanalysisforIMConlyaccidents.AccordingtothechisquaredanalysisofVMCOnlyaccidents,theproportionoffatalandnon‐fatalaccidentsintheJHIMDATdatawasnotstatisticallydifferentfromtheJHSATdata.ThesameconclusionwastrueforIMCOnlyaccidents.

Table28.VMCOnlyAccidents

85.9% (342) 86.2% (426)14.1% (56) 13.8% (68)




InjuryOutcome JHIMDAT(CY09‐11):398VMCAccidents


Non‐FatalFatal


Table29.IMCOnlyAccidents

41.2% (7) 37.9% (11)58.8% (10) 62.1% (18)


Fatal




InjuryOutcomeJHIMDAT(CY09‐11):17IMCAccidents

JHSAT(CY00‐01,06):29IMCAccidents

Non‐Fatal

36

WeatherCondition’sInfluenceonFatal&Non‐FatalAccidentsTheJHIMDATanalyzedwhetheradifferenceintheweatherconditions(eitherVMCorIMC)resultedinanystatisticaldifferenceregardingtheproportionoffatalandnon‐fatalaccidents.ThisisdifferentfromtheprecedingsectionwheretheJHIMDATseparatelyanalyzedtheVMCOnlyaccidentsandtheIMCOnlyaccidents.Inthiscase,thechisquaredanalysisusedthesametwodimensionalapproachastheearliersectionofthereporttitled“OccurrenceCategoryasRelatedtoFatal&Non‐FatalAccidents”.Theweathercondition(eitherVMCorIMC)wasonedimension.Theinjuryoutcome(eitherfatalornon‐fatal)wastheseconddimension.Becauseofthetwodimensions,theteamusedachisquaredtestofhomogeneity(ratherthanachisquaredgoodnessoffit)forthecomparison.Thetestofhomogeneityhadtobeconductedindependentlyoneachdataset,meaningthattheJHIMDATdataandJHSATdatawerenotcomparedtoeachotherwithinthesametest.However,oncethetestwasseparatelycompletedoneachrespectivedataset,theJHIMDATcouldthendetermineiftheresultsofthetestofhomogeneityhadchangedfromtheJHSATdatatotheJHIMDATdata.Toinitiatetheanalysis,theJHIMDATfirstcategorizedeachaccidentintheJHSATdataintotwogroups.ThefirstgroupwasallaccidentsthatoccurredduringVMC,whilethesecondgroupwasallaccidentsthatoccurredduringIMC.Afterthisinitialgrouping,theteamfurtherdividedtheJHSATdataintofatalaccidentsandnon‐fatalaccidents.OncetheteamcompletedthisdivisionofdataforeachaccidentintheJHSATdata,wealsousedthesamemethodofcategorizationfortheJHIMDATdata.ThestatisticalconclusionreachedfromthechisquaredtestofhomogeneitywasthesamewhenresultsfromtheJHIMDATdatawerecomparedtoresultsfromtheJHSATdata.TherewasastatisticaldifferencebetweenVMCandIMCaccidentsregardingtheproportionoffatalandnon‐fatalaccidentsforeachdataset.ThestandardizedresidualidentifiedthemajorstatisticalcontributorstothedifferencewerethatIMCaccidentshadfewernon‐fataloutcomesandmorefataloutcomesthanstatisticallyexpected.Theproportionsoffatalandnon‐fatalaccidentsfromtheJHIMDATandJHSATdataareshowninTable30.Table30.VMCandIMCRelatedtoInjuryOutcomeJHIMDAT(CY09‐11)Data NotFatal Fatal

VMC 85.9% (342/398) 14.1% (56/398)IMC 41.2% (7/17) 58.8% (10/17)

JHSAT(CY00‐01,06)Data NotFatal FatalVMC 86.2% (426/494) 13.8% (68/494)IMC 37.9% (11/29) 62.1% (18/29)

37

LightConditionTheteamgroupedaccidentsfrombothdatasetsaccordingtowhethertheaccidentoccurredduringthedayorduringthenight.Wecategorizedthefollowinglightconditionsas“night”forpurposesoftheanalysis:dawn,dusk,twilight,nightbright,andnightdark.NotethattherewasnotlightconditiondataavailableforoneoftheaccidentsintheJHSATdataandeightoftheaccidentsintheJHIMDATdata.Absenceofthisdata,however,didnotaffectthestatisticaloutcome.Therewasnotastatisticallysignificantdifferenceintheproportionofdayandnightaccidentsbetweenthetwodatasets.Table31liststhepercentagesofaccidentscategorizedbylightconditionforboththeJHIMDATandJHSATanalyses.Table31.LightConditionComparison

87.7% (357) 87.2% (455)12.3% (50) 12.8% (67)


* Lightconditionnotreportedfor8JHIMDATaccidentsand1JHSATaccident



Weather JHIMDAT(CY09‐11):407*Accidents JHSAT(CY00‐01,06):522*Accidents

DayNight


38

AccidentsbyPilot’sFlightHoursTheteamanalyzedaccidentsfromtheJHIMDATdataandtheJHSATdatausingtwodifferenttypesofpilot’sflighthours:rotorcraftflighthoursandmake/modelflighthours.Amajorlimitationwasassociatedwithdrawingconclusionsrelatedtotheproportionofaccidentsascategorizedbypilot’sflighthoursinaspecificflighthourincrement.Thelimitationwasthattheactualflighthourswereunknownforthenon‐accidentU.S.helicopterpilots.Historicalstudiesthatpre‐dateIHSTsuggestedthepercentageofhelicopteraccidentsassociatedwithaspecificincrementofpilot’sflighthourshaveahighpositivecorrelationtothepercentageofthetotalpopulationofhelicopterpilots(accidentpilotsandnon‐accidentpilots)withineachcorrespondingpilot’sflighthourincrement.Ifthesepasthistoricalstudiescontinuetobereliable,thefollowingexampleillustratestheimplications.Itwouldbepossiblethatifthepercentageofaccidentsistwiceashighforpilotswith0‐500hoursrotorcrafthoursascomparedtopilotswith501‐1,000rotorcrafthours,thereasonmaybeattributabletothetotalpopulationofpilotswith0‐500rotorcrafthoursbeingtwiceaslargeasthepopulationofpilotswith501‐1,000rotorcrafthours.Thisconclusionisquitedifferentthanconcludinglowerflighthoursalone(lessflyingexperience)isthecauseofwhypilotswith0‐500rotorcrafthourshavetwiceasmanyaccidentsasthoseinthe501‐1,000hourincrement.Inthecontextofacomparativeanalysissuchasthisreport,thesamelimitationapplies.Theunderlyingreasonaspecificpilot’sflighthourincrementmayshowastatisticaldifferenceinproportionofaccidentsbetweentheJHIMDATdataandtheJHSATdatamaybebecausetheflighthourincrementsforthetotalpopulationofpilotsmayhavechanged.Insummary,anyconclusionsrelatedtoanincreaseordecreaseinthepercentageofrotorcraftaccidentsassociatedwithaspecificpilotflighthourincrementmustincludedeliberationoftheincreasesordecreasesassociatedwiththetotalpopulationofpilotsinthatsameflighthourincrement.RotorcraftFlightHoursTheteamanalyzedtheaggregategroupofaccidentsfromtheJHIMDATdatabyrotorcraftflighthourincrementsagainsttheaggregategroupofJHSATdatabyrotorcraftflighthourincrements.Weusedflighthourincrementsof500flighthoursfrom0upto7,500flighthours(e.g.0‐500hours,501‐1,000hours,1,001‐1,500hours,etc.).Therewereaccidentswherethepilothadgreaterthan7,500rotorcraftflighthours.However,thenumberofpilotspereach500hourincrementabove7,500rotorcraftflighthourswaslow.Whentheteamorganizedthedataandincludedcasesabove7,500rotorcraftflighthoursinthechisquaredanalysis,wefoundthatmostofthe500hourincrementsabove7,500rotorcrafthourshadlessthanfiveexpectedevents.Forcaseswheredegreesoffreedomaregreaterthan1,bestpracticefromstatisticalreferencesourcessuggestedthatnomorethan20%oftheoveralldatasetshouldhave“expected”numberofeventslessthanfive.Ifthe500hourincrementsabove7,500rotorcrafthourshadbeenincluded,thedatasetwouldexceedthe20%threshold.Intheinterestofensuringanaccuratestatisticalanalysis,theteamelectedtoexcludeaccidentswherethepilothadmorethan7,500hours.

39

Accordingtothechisquaredanalysis,therewasnotastatisticallysignificantdifferencebetweenthetwodatasetswhencomparingaccidentsbyrotorcraftflighthoursforpilotswithupto7,500rotorcrafthours.Ofnote,however,isthatthedifferencewouldhavebeenstatisticallysignificantatpvaluesgreaterthanorequalto.03(rememberp=.01wasusedforstatisticalanalysisthroughouttheComparativeReport).Largemagnitudedifferenceswereevidentfortheincrementsof0‐500hoursand501‐1,000hours(proportionsofaccidentsincreasedforbothcases)aswellastheincrementsof2,001‐2,500hoursand3,501‐4,000hours(proportionofaccidentsdecreasedinbothcases).ForboththeJHIMDATandJHSATdata,Table32liststhepercentagesofaccidentscategorizedbyrotorcraftflighthoursforcaseswherethepilothadupto7,500hours.Notethatpercentagesinthetablearebasedonlyonthenumberofpilotswithupto7,500hours.Table32.AccidentsbyRotorcraftFlightHoursforPilotswith<or=7,500Hours

33.7% (87) 25.9% (97)15.9% (41) 11.7% (44)9.3% (24) 10.9% (41)9.7% (25) 8.3% (31)4.7% (12) 8.3% (31)5.4% (14) 5.3% (20)5.0% (13) 4.8% (18)1.6% (4) 4.0% (15)3.9% (10) 4.5% (17)2.3% (6) 2.7% (10)1.9% (5) 4.3% (16)1.6% (4) 1.9% (7)1.2% (3) 3.2% (12)2.3% (6) 2.1% (8)1.6% (4) 2.1% (8)

1001‐1500

PilotRotorcraftHoursJHIMDAT(CY09‐11):

258Pilots<or=7,500HoursJHSAT(CY00‐01,06):

375Pilots<or=7,500hours0‐500

501‐1000

7001‐7500

1501‐20002001‐25002501‐30003001‐35003501‐40004001‐45004501‐50005001‐55005501‐60006001‐65006501‐7000

Figure1illustratesthedistributionofpilots’rotorcrafthourswithoutlimitingthedatasettocasesatorbelow7,500hours.Forpurposesofconsolidatingthedatainthefigure,allcaseswherethepilot’smake/modelflighthoursexceeded10,000flighthourswereincludedinonecategory,showninthetableas“10,001+”.Thefigureincludesdatafrom306accidentsintheJHIMDATdataand459accidentsintheJHSATdata.Asnotedinthefigure,therewasnotpilotrotorcraftflighthourdataavailablefor109JHIMDATaccidentsand64JHSATaccidents.Thecomparativelylargemagnitudeoftheaccidentsinthe“10,001+”categoryofFigure1maybemisinterpreted.Intheinterestofavoidingpotentialconfusion,itisimportanttonotethatthiscategoryisnotorganizedbya500hourincrementlikeallothercategoriesinthefigure.Therefore,therecannotbeameaningfulcomparisonbetweenthe“10,001+”categoryandallothersinthefigure.Theintentwastokeepthecontentofthefiguretoareasonablesizewhilestillaccounting

40

fortherealitythatevenpilotswiththehighestrotorcraftflighthourexperience(over10,000rotorcrafthours)arestillvulnerabletoaccidents.Figure1.DistributionofAccidentsbyPilots’RotorcraftFlightHours.

*64JHSATaccidentsand109JHIMDATaccidentsdidnothavepilotrotorcrafttime AccidentswithPilot’sRotorcraftFlightHours<or=600HoursTheteamanalyzedtheaggregategroupofaccidentsintheJHIMDATdatatotheaggregategroupofaccidentsintheJHSATdataforcaseswherethepilot’srotorcraftflighthourswerelessthanorequalto600hours.Theteamorganizedtheaccidentsthatmetthiscriterionintoincrementsof50flighthours(e.g.0‐50hours,51‐100hours,101‐150hours,etc).Theteaminitiallyorganizedthedatabasedoncasesoflessthanorequalto1,000hoursratherthan600hours.However,whenattemptingachisquaredanalysis,wefoundthatmostofthe50hourincrementsbetween600and1,000rotorcrafthourshadlessthanfiveexpectedevents.Forcaseswheredegreesoffreedomaregreaterthan1,bestpracticefromstatisticalreferencesourcessuggestedthatnomorethan20%oftheoveralldatasetshouldhave“expected”numberofeventslessthanfive.Ifthe50hourincrementsbetween600and1,000rotorcrafthourshadbeenincluded,thedatasetwouldexceedthe20%threshold.Intheinterestofensuringanaccuratestatisticalanalysis,theteamelectedtoexcludethe600to1,000hourincrements.Accordingtothechisquaredanalysis,therewasnotastatisticallysignificantdifferencebetweenthetwodatasetswhencomparingaccidentsbyrotorcraftflighthoursforpilotswith600orlessrotorcrafthours.

41

ForboththeJHIMDATandJHSATdata,Table33liststhepercentagesofaccidentscategorizedbyrotorcraftflighthoursforcaseswherethepilothadlessthanorequalto600hours.Notethatpercentagesintablearebasedonlyonthenumberofpilotswithlessthanorequalto600hours.Table33.AccidentsbyRotorcraftFlightHoursforPilotswith<or=600Hours

9.2% (9) 11.0% (12)14.3% (14) 9.2% (10)10.2% (10) 8.3% (9)6.1% (6) 11.0% (12)7.1% (7) 11.0% (12)10.2% (10) 10.1% (11)8.2% (8) 5.5% (6)10.2% (10) 11.9% (13)8.2% (8) 4.6% (5)5.1% (5) 6.4% (7)6.1% (6) 4.6% (5)5.1% (5) 6.4% (7)

101‐150


98Pilots<or=600HoursJHSAT(CY00‐01,06):

109Pilots<or=600Hours0‐5051‐100

451‐500501‐550551‐600

151‐200201‐250251‐300301‐350351‐400401‐450

AccidentsbyPilot’sMake/ModelFlightHoursTheteamanalyzedtheproportionofaccidentscategorizedbypilot’smake/modelflighthoursforboththeJHIMDATandJHSATanalyses.Theanalysisconsistedoforganizingthemake/modelflighthoursbyincrementsof500flighthoursfrom0upto4,500flighthours.Therewereaccidentswherethepilotshadgreaterthan4,500make/modelflighthours.However,thenumberofpilotspereach500hourincrementabove4,500make/modelflighthourswaslow.Forthesamereasonspreviouslycitedinthesectionsthatdescribedouranalysisofaccidentsbyrotorcraftflighthours,thecasesabove4,500make/modelflighthourscouldnotbeincludedinthechisquaredwithoutsacrificingtheaccuracyofthestatisticaltest.Accordingtothechisquaredanalysis,therewasnotastatisticallysignificantdifferencebetweenthetwodatasetswhencomparingtheaccidentsbymake/modelflighthourincrements.ForboththeJHIMDATandJHSATdata,Table34liststhepercentagesofaccidentscategorizedbymake/modelflighthoursforcaseswherethepilothadlessthanorequalto4,500hours.Notethatpercentagesinthetablearebasedonlyonthenumberofpilotswithlessthanorequalto4,500hours.

42

Table34.AccidentsbyMake/ModelFlightHoursforPilotswith<or=4,500Hours

56.6% (192) 25.9% (237)18.0% (61) 11.7% (70)10.6% (36) 10.9% (37)4.7% (16) 8.3% (30)2.7% (9) 8.3% (19)2.4% (8) 5.3% (14)2.9% (10) 4.8% (10)1.5% (5) 4.0% (7)0.6% (2) 4.5% (10)4001‐4500

PilotMake/ModelHoursJHIMDAT(CY09‐11):


434Pilots<or=4,500hours0‐500

501‐10001001‐15001501‐20002001‐25002501‐30003001‐35003501‐4000

Figure2illustratesthedistributionofpilots’make/modelflighthourswithoutlimitingthedatasettocasesatorbelow4,500hours.Forpurposesofconsolidatingthedatainthefigure,allcaseswherethepilot’smake/modelflighthoursexceeded10,000flighthourswereincludedinonecategory,showninthetableas“10,001+”.Thefigureincludesdatafrom370accidentsintheJHIMDATdataand472accidentsintheJHSATdata.Asnotedinthefigure,therewasnotpilotmake/modelflighthourdataavailablefor45JHIMDATaccidentsand51JHSATaccidents.Figure2.DistributionofAccidentsby‐Pilots'Make/ModelFlightHours

*51JHSATaccidentsand45JHIMDATaccidentsdidnothavepilotmake/modeltime

43

AccidentswithPilot’sMake/ModelFlightHours<or=1,000HoursTheteamanalyzedtheproportionofaccidentsfromboththeJHIMDATandJHSATanalysesforcaseswherethepilotintheaccidenthadlessthanorequalto1,000make/modelflighthours.Theanalysisconsistedoforganizingthemake/modelflighthoursbyincrementsof50flighthoursfrom0upto1,000flighthours.Accordingtothechisquaredanalysis,theJHIMDATdatawasstatisticallydifferentfromtheJHSATdata.Theflighthourincrementswherethenumberofaccidentschangedenoughtobeamajorcontributortothestatisticaldifferencewere:

FlightHourIncrement Change451‐500hours Increasedfrom2.0%to4.3%ofaccidents651‐700hours Increasedfrom1.6%to3.6%ofaccidents801‐850hours Increasedfrom0.7%to2.4%ofaccidents

Table35.AccidentsbyMake/ModelFlightHoursforPilotswith<or=1,000Hours

12.6% (32) 16.0% (49)14.2% (36) 12.1% (37)9.9% (25) 7.8% (24)5.9% (15) 6.8% (21)5.5% (14) 7.8% (24)6.7% (17) 9.4% (29)7.5% (19) 5.2% (16)5.9% (15) 7.5% (23)3.2% (8) 2.6% (8)4.3% (11) 2.0% (6)2.8% (7) 1.6% (5)2.0% (5) 4.2% (13)1.2% (3) 1.6% (5)3.6% (9) 1.6% (5)3.6% (9) 2.6% (8)2.0% (5) 3.3% (10)2.4% (6) 0.7% (2)2.0% (5) 2.3% (7)1.6% (4) 2.6% (8)3.2% (8) 2.3% (7)

101‐150



307Pilots<or=1,000Hours0‐5051‐100

701‐750

151‐200201‐250251‐300301‐350351‐400401‐450451‐500501‐550551‐600601‐650651‐700

751‐800801‐850851‐900901‐950951‐1,000

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Figure3illustratesthedistributionofpilots’make/modelflighthoursforpilotswithlessthanorequalto1,000hours.Figure3.AccidentsbyMake/ModelFlightHoursforPilotswith<or=1,000Hours

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InfluenceofMake/ModelFlightHoursonFatal&Non‐FatalAccidents TheJHIMDATanalyzedwhetherthequantityofpilot’smake/modelflighthoursresultedinanystatisticaldifferenceregardingtheproportionoffatalandnon‐fatalaccidents.Inthiscase,thechisquaredanalysisusedthesametwodimensionalapproachastheearliersectionsofthereporttitled“OccurrenceCategoryasRelatedtoFatal&Non‐FatalAccidents”and“WeatherConditionasRelatedtoFatal&Non‐FatalAccidents”.Thepilot’smake/modelhourswereonedimension.Theinjuryoutcome(eitherfatalornon‐fatal)wastheseconddimension.Becauseofthetwodimensions,theteamusedachisquaredtestofhomogeneity(ratherthanachisquaredgoodnessoffit)forthecomparison.Thetestofhomogeneityhadtobeconductedindependentlyoneachdataset,meaningthattheJHIMDATdataandJHSATdatawerenotcomparedtoeachotherwithinthesametest.However,oncethetestwasseparatelycompletedoneachrespectivedataset,theJHIMDATcouldthendetermineiftheresultsofthetestofhomogeneityhadchangedfromtheJHSATdatatotheJHIMDATdata.Toinitiatetheanalysis,theJHIMDATfirstcategorizedeachaccidentintheJHSATdataintotwogroups.Thefirstgroupwasallaccidentsthatoccurredwherepilotshadatorbelowaspecificmake/modeltime(e.g.,<or=100hours),whilethesecondgroupwasallaccidentsthatoccurredwherepilotshadaboveaspecificmake/modeltime(e.g.>100hours).Afterthisinitialgrouping,theteamfurtherdividedtheJHSATdataintofatalaccidentsandnon‐fatalaccidents.OncetheteamcompletedthisdivisionofdataforeachaccidentintheJHSATdata,wealsousedthesamemethodofcategorizationfortheJHIMDATdata.Theteamperformedthetestofhomogeneity10timesforeachdataset,correspondingtomake/modelflighthoursdivisionsevery100hoursstartingwith100hoursandconcludingwith1,000hours.ThestatisticalconclusionreachedfromthechisquaredtestofhomogeneitywasthesamewhenresultsfromtheJHIMDATdatawerecomparedtoresultsfromtheJHSATdata.Consistentlyforeachofthe10differentmake/modelflighthourintervalsanalyzed,therewasnotastatisticaldifferenceforanycaseforeithertheJHSATortheJHIMDATdatasetregardingtheproportionoffatalandnon‐fatalaccidents.

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SummaryandConclusionsInthecomparativeanalysisofU.S.helicopteraccidentsfromtheJHIMDATdata(2009‐2011)againsttheJHSATdata(2000,2001,and2006),theteamobservedthateitherstagnancyorregressionwasthemostevidentcharacteristic.Themostfrequentlyciteditemswereconsistentbetweenthedatasetsinmanyofthedifferentanalysisareas.IntheIndustryanalysis,thetopfiveindustriesfromTable1werethesameandappearedinthesamerankorderfromtheJHSATdatatotheJHIMDATdata:1)Personal/Private,2)Instructional/Training,3)AerialApplication,4)EmergencyMedicalServices,and5)Commercial.Thesefiveindustriesaccountedforabout70%ofallU.S.accidentsintheJHIMDATdata,soimplementationmeasuresmusttargetmoreimprovementintheseindustriestostimulatemoresignificantaccidentreductions.Regrettably,thestatisticalanalysisshowednosignificantdifferencebetweentheproportionsofaccidentsinfourofthetopfiveindustries,anindicationofstagnancy.TheonlyIndustrywheretheteamnotedastatisticallysignificantdifferencewasinAerialApplication,whereregressionoccurredasevidentbythesignificantlyhigherproportionofaccidents.TheIndustry/ActivitypairsfromTable3reinforcedtheobservationsabouthowalargevolumeoftheaccidentsaredisproportionatelyrepresentedbyasmallnumberofindustries.ThethreemostfrequentlycitedIndustry/ActivitypairsfromtheJHIMDATanalysisaccountedforover40%oftheaccidentsfrom2009‐2011.AccidentsfromthePersonal/PrivateIndustryengagedinaPersonal/PrivateActivityaccountedforthehighestpercentageofaccidentsobservedintheJHIMDATdataandshowedastatisticallysignificantincreaseintheproportionofaccidentsfromtheJHSATdata.ThesecondandthirdmostfrequentIndustry/ActivitypairingsintheJHIMDATdataweretiedtotheInstructional/TrainingandAerialApplicationIndustrysectors.BothofthesepairingsshowedstagnancyinthattherewasnostatisticallysignificantchangeintheproportionofaccidentsobservedintheJHIMDATdatawhencomparedtotheJHSATdata.AseparatebutstillperplexingproblemintheIndustryandActivitypairsishowfrequentlythePositioning/RTBActivityresultsinaccidentsforboththeEmergencyMedicalServiceandAerialApplicationindustries.Positioning/RTBinvolvesmovingthehelicopterfromonelocationtoanotherandisnottypicallycharacterizedbythesamelevelofcomplexityaseitheroftheseIndustrysectorswouldexperienceinexecutingtherestoftheirtypicalflightprofile.Yet,Positioning/RTBwaspreciselytheActivitythataccountedforthehighestnumberofaccidentsineachofthesetwoIndustrysectors.IntheOccurrenceCategoryanalysisfromTable4,therankorderforfiveoutofthetopsixOccurrenceCategoriesintheJHIMDATdatamatchedtheJHSATdataandprovidedfurtherevidencethattheareasinneedofthestrongestimplementationmeasureshadnotchanged.LossofControlcontinuedtohavethehighestfrequencyofoccurrenceandalsoshowedastatisticallysignificantregression.OneofthepositiveobservationsintheOccurrenceCategoryanalysiswasthattheSystemComponentFailurecategoryhadastatisticallysignificantimprovement.TheSub‐OccurrenceCategoryanalysisfromTable5revealedthiswasattributabletoastatistically

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significantimprovementinthehelicopterrelatedSystemComponentFailures(versusthosethatwereenginerelated).Unfortunately,therestofthemostfrequentlycitedSub‐OccurrenceCategoriesshowedeitherstagnationorregression.The21%reductioninthenumberofaccidentsthatoccurredinthethreeyearscoveredbytheJHIMDATdata(415accidents)ascomparedtothethreeyearsintheJHSATdata(523accidents)isprogressandshouldnotbedisregardednorminimized.However,thecomparativeanalysisbetweenthetwodatasetsclearlyshowedthattheareasresponsibleforthemajorityofU.S.helicopteraccidentsrequiremoreattentioninordertoachieveamoresignificantreductionintheoverallnumberofaccidents.Akeyelementmissingfromthecomparativeanalysisbetweenthedatasetswasclearanswerstocritical“Why”questions.Forexample,“Whyisstagnancyandregressionsoprevalentintheanalysis?”or“Whyhaveimplementationmeasuresbeenlesseffectiveintheseareas?”TheoriginofthesequestionsisthatwewereuncertainastowhatextentanyofthetoolsandresourcesdevelopedbytheIHSThadeverreachedactualimplementationwithhelicopteroperators.Theambiguityleftopenseveralpossibilities.Perhaps,somedegreeofimplementationoccurredyetdidnotproduceanyimprovement.Unfortunately,thereisalsothepossibilitythatimplementationmayneverhaveoccurredatall.Therewasnoclearevidenceforeitherofthesetwoscenariosoranyothers,sothisreportchosenottospeculatefurther.However,theprevalenceofstagnancyandregressioninthecomparativeanalysismadeitclearthattheimplementationmeasuresforthehighestaccidentproducingIndustrysegmentsshouldbereevaluated.TheUSHSTmusteitherdevelopmorerigorousimplementationmeasuresorformulateamoreeffectiveplanforensuringthatoperatorsareactivelyusingtheimplementationresourcesalreadyavailable.

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ReferencesU.S.JointHelicopterSafetyAnalysisTeam.(2011,August).TheCompendiumReport:TheU.S.

JHSATBaselineofHelicopterAccidentAnalysis,VolumeI.Retrievedfromhttp://www.ihst.org/portals/54/US_JSHAT_Compendium_Report1.pdf

U.S.JointHelicopterSafetyAnalysisTeam.(2011,July).TheCompendiumReport:TheU.S.JHSATBaselineofHelicopterAccidentAnalysis,VolumeII.Retrievedfromhttp://www.ihst.org/portals/54/US_JSHAT_Compendium_Report2.pdf