wolfgang loppitsch stamp modeling of the accident n4252g

VehicleSafetyInstitute

WolfgangLoppitsch

STAMPModelingoftheAccident

N4252G

MASTER’STHESIStoachievetheuniversitydegreeof

MasterofEngineering

Master’sDegreeProgram:TrafficAccidentResearch-AviationSafety

Submittedto

GrazUniversityofTechnology

Supervisors: Priv.-Doz.Dr.IoanaKoglbauer

Ao.Univ.-Prof.Dr.techn.ReinhardBraunstingl

VehicleSafetyInstitute

Graz,March,2019

TUGrazIMasterthesis

AFFIDATIV

IdeclarethatIhaveauthoredthisthesisindependently,thatIhavenotusedotherthanthedeclared

sources/ resources, and that I have explicitly marked all material which has been quoted either

literally or by content from the used sources. The text document uploaded to TUGRAZonline is

identicaltothepresentmaster‘sthesis.

Graz,March29,2019 _________________________________

Signature

TUGrazIMasterthesis

Preface

I

PREFACE

Followingalonginterest inaviationsafety, IhaveattendedtheMaster’sDegreeProgramofTraffic

AccidentResearch-AviationSafetyattheUniversityofTechnology,Graz,Austria.

Myexperienceasaprofessionalpilot ranges fromsingle-enginepistonaircraft via theBombardier

Global Express long-range corporate aircraft to the Airbus A320 type. Besides, I have gained

experienceasaflightoperationsofficer,aflightinstructor/examinerforsingle-enginepistonaircraft,

a type-rating instructor/ examiner and flight operations inspector for the Austrian Civil Aviation

Authority.

Reoccurringcasesofrathersimilaraircrasheswithsingle-enginepistonaircrafthaveinitiatedvarious

discussions about the model-based improvement of accident investigation processes used for

modernGeneralAviationaircraft,whichhaveledtothedevelopmentofthisthesis.

Atthisfinalstageofmystudies,Iwouldliketotaketheopportunitytothankmyfamilyandfriends

forsupportingandencouragingmetocontinuetowardsmyacademicgoals.Finally, Iwould liketo

thankmyacademicsupervisorsfortheirkindhelpandsupportduringthedevelopmentofthisthesis.

TUGrazIMasterthesis

Abstract

II

ABSTRACT

Thepresentmaster'sthesisaimstocomparetheresultsofatraditionalaccidentinvestigationreport

publishedby the investigatingparty (NTSB)anda system-theoreticalmodelingbasedonLeveson’s

STAMPmodelandCASTmethodology(Leveson,2011).

Today’s accident analyses reports are often based on linear accident models that allow the

identification of only a limited number of causes, and safety recommendations for avoiding such

accidents in the future. The accident ofN4252Gwas published in great detail via socialmedia by

meansofphotosandvideorecordings.Theassociatedcausesresultingfromtheaccidentreport,and

thesafetyrecommendationsdidnot includeallthelessonsthatcouldbelearntfromthisaccident.

Thus,themotivationwasgiventosystemicallymodelthisaccidenttoprovideasystemicviewofits

causes.

OnJune9,2016,aCirrusSR20registeredaircraftcrashedatWilliamPHobbyAirport(HOU),Texas,

USA,andallthreepersonsonboardlosttheirlives.ThepilottriedseveraltimestolandinHOU.The

firstapproachwascancelledbyATCforsubsequentcommercialairtraffic.Theaircraftremainedon

towerfrequencyunderhigh-trafficsituations.ThesecondlineupforapproachwascancelledbyATC.

Twomoreapproacheswereexecuted,whichallendeduptoohighanddidnotallowasafelanding.

During the lastgo-aroundprocedure, theATCcontrollerwas relieved.Thepilot lost controlof the

aircraft at about 500ft above ground level, causing a spin. The aircraft impacted in anempty car,

whichwas parked near a hardware store. The accident site was located about half amile of the

approached runway. The weather was characterized by good visibility and strong and gusty

crosswindsupto20kts.

Considering a list of relevant definitions, the most important facts referring to the accident and

technicalaspectsoftheaircraftweresummarizedintheappendicesofthisthesis.Thetimelimitof

theanalysiswasdefinedfromthefirstcontactwithHOUATCuntiltheaccident.Theanalysisofpost-

crasheventswasexcluded.Fordetailedillustration,relevantstoredflightdataoftheon-boarddata

module and position logs from radar data were presented graphically together with the time-

referenced ATC transmissions. Using the Systems-Theoretic Accident Model and Process STAMP

(Leveson,2011),thisthesisproposesanSTPA-basedmodeloftheaccidentthatincludesthecontrol

structures of ten individual system components, unsafe control actions, dysfunctional interactions

and contextual factors. The STAMP-based model of the accident allowed to generate 55 safety

recommendationsand64raisedquestions.TheresultsillustratetheexistingpotentialofSTAMPand

CAST (Leveson,2011) for improvingtheaviationaccident investigationandshowsthat thepresent

aviationaccidentcouldbeinvestigatedandunderstoodinmoredetailbyapplyingSTAMPandCAST.

TUGrazIMasterthesis

TableofContents

III

TABLEOFCONTENTS

1 INTRODUCTION 2

1.1 Motivation 2

1.2 Objectives 2

2 STAMPANALYSISOFTHEN4252GACCIDENT 3

2.1 DefinitionofRestrictingConditionsandTimeLine 3

2.2 RadarDataandGraphicalPresentationofFlightData 4

2.3 GeneralDefinitionsforthePresentCASTAnalysis 42

2.4 GeneralModelofHierarchicalControlStructure 44

2.5 ProcessModelforeachSystemComponent 45

2.5.1 HigherControlLevel(HCL)-ControlStructure 46

2.5.2 TrainingOrganisation-ControlStructure 49

2.5.3 ATC-ControlStructure 51

2.5.4 AircraftManufacturer(Cirrus)-ControlStructure 56

2.5.5 COPA-ControlStructure 58

2.5.6 HOUAirport-ControlStructure 59

2.5.7 Operator/AircraftOwner-ControlStructure 60

2.5.8 Pilot-ControlStructure 61

2.5.9 Passengers-ControlStructure 66

2.5.10 Aircraft-ControlStructure 67

3 RESULTS 69

4 DISCUSSION 78

5 CONCLUSIONS 79

6 REFERENCES 80

APPENDIX A-1A

TUGrazIMasterthesis

TableofContents

IV

DefinitionofRelevantTerms A-1

APPENDIX B-1B

LossofControlinGeneralAviation B-1

APPENDIX C-1C

GeneralInformationaboutSTAMP C-1

HierarchicalControlStructure(HCS)inSTAMP C-2

APPENDIX D-1D

HistoryofFlightN4252G D-1

SummaryofBasicEventsofFlightN4252G D-2

Pilot-Information D-4

Pilot-ExperienceLevel D-5

APPENDIX E-1E

RelevantAspects-SR20PilotOperatingHandbook(POH) E-1

RelevantAspects-SR20FlightOperationsManual(FOM) E-6

APPENDIX F-1F

ResultsRaisedbytheNTSBFinalReport F-1

APPENDIX G-1G

ChainofEvents G-1

APPENDIX H-1H

InterviewswithATCControllersheldbyNTSB H-1

TUGrazIMasterthesis

TableofContents

V

APPENDIX I-1I

SummaryofCFIStatements I-1

APPENDIX J-1J

RecordedFlightData J-1

APPENDIX(SYSTEMCOMPONENTS) K-1K

APPENDIX(ILLUSTRATIONS) L-1L

APPENDIX(ATCTRANSCRIPT) M-1M

TUGrazIMasterthesis

ListofFigures

VI

LISTOFFIGURES

Figure2-1OverviewofN4252G’sgroundtrackinthevicinityofHOU...................................................4

Figure2-2Initialapproachtorunway4andATC-directedgo-around....................................................9

Figure2-3Maneuversfollowingtheinitialgo-around..........................................................................12

Figure2-4Continuedpatternmaneuvers.............................................................................................15

Figure2-5Continuedpatternmaneuvers.............................................................................................18

Figure2-6Changingapproachfromrunway4torunway35................................................................21

Figure2-7Settingupforinitialstraight-inapproachtorunway35......................................................24

Figure2-8Runway35firstapproachandgo-around............................................................................27

Figure2-9Preparingforsecondapproachtorunway35.....................................................................30

Figure2-10Downwindtofinalturn,secondapproachtorunway35..................................................33

Figure2-11Secondapproachtorunway35.........................................................................................36

Figure2-12Go-aroundfollowingsecondapproachtorunway35andlossofcontact........................39

Figure2-13Generalmodelofhierarchicalcontrolstructure...............................................................44

Figure2-14HCL-simplifiedcontrolstructure......................................................................................46

Figure2-15Trainingorganisation-simplifiedcontrolstructure..........................................................49

Figure2-16ATC-simplifiedcontrolstructure......................................................................................51

Figure2-17Aircraftmanufacturer-simplifiedcontrolstructure.........................................................56

Figure2-18COPA-simplifiedcontrolstructure...................................................................................58

Figure2-19HOUairport-simplifiedcontrolstructure.........................................................................59

Figure2-20Operator/Aircraftowner-simplifiedcontrolstructure....................................................60

Figure2-21Pilot-simplifiedcontrolstructure.....................................................................................61

Figure2-22Passengers-simplifiedcontrolstructure...........................................................................66

Figure2-23Aircraft-simplifiedcontrolstructure................................................................................67

Figure3-1Generalmodelofhierarchicalcontrolstructureincludingresults......................................77

Figure6-1HOUairportdiagram...........................................................................................................L-1

Figure6-2GuidanceforestablishingPersonalWeatherMinimums...................................................L-2

Figure6-3EnvelopeofSafety..............................................................................................................L-3

Figure6-4Windcomponentdiagram..................................................................................................L-4

TUGrazIMasterthesis

ListofTables

VII

LISTOFTABLES

Table2-1SummaryofATCtransmissions,12:52:47-12:57:02CDT......................................................6

Table2-2HCL-CASTanalysis................................................................................................................48

Table2-3Trainingorganisation-CASTanalysis....................................................................................50

Table2-4ATC-CASTanalysis................................................................................................................55

Table2-5Aircraftmanufacturer-CASTanalysis...................................................................................57

Table2-6COPA-CASTanalysis.............................................................................................................58

Table2-7HOUairport-CASTanalysis..................................................................................................59

Table2-8Operator/Aircraftowner-CASTanalysis.............................................................................60

Table2-9Pilot-CASTanalysis...............................................................................................................65

Table2-10Passengers-CASTanalysis..................................................................................................66

Table2-11Aircraft-CASTanalysis........................................................................................................68

Table3-1Safetyrecommendations......................................................................................................74

Table3-2Questionsraised....................................................................................................................77

Table6-1SummaryofATCtransmissions,12:57:02-13:08:45CDT.................................................M-2

TUGrazIMasterthesis

ListofDiagrams

VIII

LISTOFDIAGRAMS

Diagram2-1Visualdescentangledirecttotheaimingpoint,12:27:56-12:56:30CDT........................6

Diagram2-2Graphicaldepictionofbasicflightdata,12:27:48-12:56:32CDT.....................................7

Diagram2-3Visualdescentangledirecttotheaimingpoint,12:56:54-12:58:07CDT........................9

Diagram2-4Graphicaldepictionofbasicflightdata,12:57:02-12:58:06CDT...................................10

Diagram2-5Visualdescentangledirecttotheaimingpoint,12:57:55-12:59:07CDT......................12





Diagram2-10Graphicaldepictionofbasicflightdata,12:59:59-13:00:47CDT.................................19

Diagram2-11Visualdescentangledirecttotheaimingpoint,13:00:42-13:01:42CDT....................21














TUGrazIMasterthesis

ListofAbbreviationsandCodings

IX

LISTOFABBREVIATIONSANDCODINGS

AC AdvisoryCircular(FAA)

AFM AirplaneFlightManual

AGL abovegroundlevel

AIM AeronauticalInformationManual

AltB BarometriccorrectedAltitudein[feet]aboveMSL

AME AeronauticalMedicalExaminer

APS AircraftParachuteSystem

ATC AirTrafficControl

ATCT AirTrafficControlTower

ATIS AutomatedTerminalInformationService

ATM AirTrafficManagement

ATSAP AirTrafficSafetyActionProgram

Avgas AviationGasoline(forspark-ignitedpistonengines)

CAPS CirrusAirframeParachuteSystem

CASTCausalAnalysisbasedonSTAMP

(Leveson,2011)

CD ClearanceDelivery(ATC)

CDM CriticalDecisionMakingseminar(byCOPA)

CDTCentralDaylightTime(UTCminus5)

in[hours]:[minutes]:[seconds]

CFI CertifiedFlightInstructor

CG CenterofGravity

CFR CodeofFederalRegulations(USA)

CHT CylinderHeadTemperature

COM ATCCommunicator(52G,LCI,LCTorLCC)

COPA CirrusOperatorPilotsAssociation

CPPP CirrusPilotProficiencyProgram(byCOPA)

CSIP CirrusStandardizedInstructorPilot

CTC CirrusTrainingCenter

TUGrazIMasterthesis


X

Dist Distancein[NM]

DMS DocketManagementSystem

EGT ExhaustGasTemperature

FAA FederalAviationAdministration

FOM FlightOperationsManual

ft feet(1ftequals0.3048meters)

FD FlightData(ATC)

FITS FAAIndustryTrainingStandards

FLM FrontLineManager(ATC)

fpm feetperminute

GAJSC GeneralAviationJointSteeringCommittee

GA GeneralAviation

GC GroundControl

GGG GreggCountyAirport,Longview,Texas

GS GroundSpeedin[kts]

H Hazard

HCL HigherControlLevel

HLSC High-LevelSafetyConstraints

Hobby shortformforHOUairport

IFR InstrumentFlightRules

HCS HierarchicalControlStructure

HDG MagneticHeadingin[°]

HOU WilliamP.HobbyAirport,Houston,Texas

I90 HoustonTerminalRadarApproachControl

IAS IndicatedAirspeedin[kts]

ICAO InternationalCivilAviationOrganisation

ISA InternationalStandardAtmosphere

kgs kilograms

KIAS IndicatedAirspeedin[kts]

kts knots[1ktisequalto1NMperhour]

L Loss

TUGrazIMasterthesis


XI

lbs pounds[1lbisequalto2.2kgs]

LC LocalControl(ATC)

LCC LocalControl–Controller(ATC)

LCT LocalControl–Trainee(ATC)

LCI LocalControl–Instructor(ATC)

LDA LandingDistanceAvailable

LOC LossofControl

mile equaltonauticalmile[NM]

MSL meansealevel

NM NauticalMile[1NMequals1852metersequals6076ft]

NATCA NationalAirTrafficControllersAssociation

NTSBNationalTransportationSafetyBoard

(investigatingparty)

OJT on-the-jobtraining

OJTI on-the-jobTrainingInstructor(ATC)

OUN UniversityofOklahomaWestheimerAirport

PAPI PrecisionApproachPathIndicator

Paxe Passengers

PD Policedepartment

PIC Pilotincommand

POH Pilot’sOperatingHandbook

PRC PerformanceRecordsofConference

QR Questionsraised

RadarAltitude AltitudeindicatedonATCradarmonitorin[ft]

RDM RecoverableDataModule

REC Recommendation

RPM revolutionsperminute

RY Runway

SA SituationalAwareness

SC SafetyRequirementsandConstraints

SRM Single-PilotResourceManagement

TUGrazIMasterthesis


XII

SSR SecondarySurveillanceRadar

STAMP SystemsTheoreticAccidentModelingandProcesses(Leveson,2011)

STARS StandardTerminalAutomationReplacementSystem

STPA System-TheoreticProcessAnalysis(Leveson,2011)

SWA SouthwestAirlines

TAA Technologically-AdvancedAircraft

TCI TrainingCenterInstructor

TrOrg TrainingOrganisation

UCA UnsafeControlAction

US UnitedStates

US-gal USgallon[1US-galequals3.785liters]

UTC UniversalTimeCoordinated(generalmeantime)

Vfe maximumflapsextendedspeedin[kts]

Vno maximumnormaloperatingspeedin[kts]

Vs Stallspeedin[kts]

Vs0

“minimumsteadyflightspeedinthelandingconfiguration”(USDepartmentofTransportation,Pilot’sHandbookofAeronauticalKnowledge,2016,p.8-9)in[kts]

Vy“bestrateofclimbspeed”(USDepartmentofTransportation,Pilot’sHandbookofAeronauticalKnowledge,2016,p.G-34)in[kts]

VFR VisualFlightRules

VMC VisualMeteorologicalConditions

WINGS FAAPilotProficiencyProgram

x-wind cross-wind

52G ATCshortformforN4252G

Aspects that theauthorof this thesisconsidersassafetyrelevant for themodelingof theaccident

N4252GusingSTAMP(Leveson,2011)areunderlinedthroughouttheprevailingdocument.

TUGrazIMasterthesis

Introduction

1

“Thereisalmostnohumanactionordecisionthatcannotbemadetolookflawedinthemisleading

lightofhindsight.Itisessentialthatthecriticshouldkeephimselfconstantlyawareofthatfact.”

SirAnthonyHiddenQC(March7,1936–February19,2016)

TUGrazIMasterthesis

Introduction

2

1 INTRODUCTION

1.1 Motivation

After an aircraft accident, questions concerning what caused it are soon raised. The aeronautical

regulativesprovideaframeworkfortheinvestigation,althoughinmanycasesfinalaircraftaccident

reports endafter identifying causal humanerrors. Thus, opportunities aremissed to identify why

humans behaved in the way that they did and what preventive measures could prevent people

repeating the same errors in the future. The official investigation report of the N4252G accident

clearlydescribestheeventsandsomerelatedrootcauses.Theanalysisofwhythesehumanerrors

occurred could be enlarged using STAMP.Understanding that a human error is a symptom rather

thanacauseholdsutmostimportance,ashumansgenerallytendtobelievethateventsassuchare

moreobviousandpredictablethanbefore.Thisiscalled“hindsightbias”,whichmightultimatelyalso

influencetheobjectivityininvestigation.InthepresentaccidentreportofN4252G,theNTSBasthe

investigationboarddeterminedtheprobablecausessolelyashuman-affectederrors.Ashumansdo

not intentionallymakemistakes, the entiremental process inwhich context decisionsweremade

must be considered, as gaps in the safety control structure ultimately allow accidents to occur.

Consideringthathumanshaveacertaincapacityforperformingprocedures,itshallbenotedthatif

taskdemandsexceedapilot’scapability, theymayeitherbenotperformedproperlyorsomemay

notbeperformedatall.Thisunderstandingistheinitialstepofadetailedsystem-theoreticprocess

analysisandwasasignificantmotivationfactorforthedevelopmentofthisthesis.

1.2 Objectives

Theaimof this thesis is toconductadetailedanalysisof theN4252GaccidentbyapplyingSTAMP

(Leveson,2011).Incomparisontoconventionalstate-of-the-artinvestigationmethodsusedbymany

accidentinvestigationparties,thisthesisinvestigatestheapplicabilityofSTAMPforinvestigatingan

aircraft accident in systemic approach rather than on the analytical reduction approach that

considers the individual components. The focus of thismaster thesis is to systemicallymodel and

analyse complex control structures. The results shall highlight the potential of applying STAMP in

accidentresearchandshownewperspectivesoftheaccidentcauses,describeunsafecontrolactions

ofindividualcomponents,definegapsandopenquestionsfromtheofficial investigationandfinally

specify safety recommendations to address critical safety issues to avoid re-occurrences of similar

accidents.Theselectionofthisrelativeunknownaccidentasabaseforthethesisisdeliberate,asit

illustratestherequirementofmoderninvestigationmethodsforthewholeaviationsafetyspectrum.

TUGrazIMasterthesis

STAMPAnalysisoftheN4252GAccident

3

2 STAMPANALYSISOFTHEN4252GACCIDENT

2.1 DefinitionofRestrictingConditionsandTimeLine

AsaninitialstepintheprevailingSTAMP(Leveson,2011)modeling,therestrictingconditionsofthe

aircraftaccidentofN4252GfromJune9,2016weredefinedbytheauthor.Thesystem-theoretictop-

down analysis starts at 12:27:48 CDT (when the pilot first contacted Houston Approach ATC) and

lasts until the impact. The post-crash events (e.g. rescue coordination) are excluded from the

analysis.Thedifficulty in theanalysisof thisaccidentwas thatpartiallycrucial informationneeded

forthefullunderstandingwasnotincludedinthefinalreportbytheinvestigatingparty.Itmustbe

noted,thatthisinformationappearsascrucialonlywhenSTAMPisbeingused.Thesequestionsare

listedinChapter3.

Themodeling of an accident according STAMP (Leveson, 2011) requires the specification of basic

eventsreferencedtothetime(“timeline”).This ispresentedinGAppendix inthesectionChainof

Events.

TUGrazIMasterthesis


4

2.2 RadarDataandGraphicalPresentationofFlightData

Asmentioned in theoriginal accident report, “Radardata for this accidentwasobtained from the

Standard Terminal Automation Replacement System (STARS) and from the Harris Opsvue radar

replay system licensed to the NTSB” (NTSB, Air Traffic Control, Group Chairman's Factual Report,

CEN16FA211,2016,p.7).Figure2-1showsanoverviewoftheaircraft’sgroundtrackinthevicinityof

HOU.

(NTSB,AirTrafficControl,GroupChairman'sFactualReport,CEN16FA211,2016,p.8)

Figure2-1OverviewofN4252G’sgroundtrackinthevicinityofHOU

Thegraphicalpresentationsof the flight trackwiththeassociatedATCtranscriptwereanalysedby

theauthortomodelthecomplexmaneuversoftheaircraftN4252Gbeforetheaccident.Itisbased

ontheplottedradarpositionsoftheN4252GRadarTargetFile1.

Figure 2-2 to Figure 2-12 illustrate the aircraft maneuvers in the vicinity of the airport with

annotationsfromtheATCtranscript(rf.(NTSB,AirTrafficControl,GroupChairman'sFactualReport,

CEN16FA211,2016,p.7)).

1TheN4252GRadarTargetFile-HOUASRGoogleEarthKMLTargetFilewasretrievedfromNTSBDMSWebsite:https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB

TUGrazIMasterthesis


5

When the ATC transcript in the ATC Factual Report (NTSB, Air Traffic Control, Group Chairman's

Factual Report, CEN16FA211, 2016) was compared with the HOU Tower Accident Package (HOU-

ATCT-0064,2018),theauthornoticedslighttimedeviations(inseconds),althoughitwasrecognized

thattheinfluenceforthefurtheranalysiswasneglectable.

Asmentioned in J Appendix, a selection of relevant flight data recordswas analysed at a physical

systemlevelbytheauthor.ThisdatawasimplementedintodiagramsfortheapplicationofSTAMP

(Leveson, 2011), seeDiagram2-1 toDiagram2-24. The engineparameters CHT and EGThavenot

been analysed, as the official NTSB investigation excluded any abnormal engine operation until

impact.Onlythepowerassetbythepilotwasconsidered.

Thefollowingabbreviationswereappliedforthegraphicalpresentation:

CDT Localtimereferencein[hours]:[minutes]:[seconds]

COM CommunicatorforATC-relatedtransmissions(52G,LCI,LCTorLCC)

Heading HeadingreferencedtoMagneticNorthin[°]

RY Anticipatedlandingrunwayforthepilot,asadvisedbyATC

___T Radaraltitudein[ft]

Ry4-Path Visual descent angle in [°] from aircraft position (based on actual radar altitude)

directtotheaimingpointofrunway4referencedtoAltB

Ry35-Path Visual descent angle in [°] from aircraft position (based on actual radar altitude)

directtotheaimingpointofrunway35referencedtoAltB

Pitch Aircraftpitchin[°],apositivepitchnumbermeansanose-upattitude

Roll Aircraftrollin[°],apositiverollnumbermeansaright-bankattitude

Power Powersettingin[%],rangingfrom0-100%

Flaps Flap setting [0, 1, 2], available flap settings correspond to numbers [0%=0, 50%=1,

100%=2]

AltB Barometriccorrectedaltitudein[ft]aboveMSL

HOUelevation 43ftaboveMSL

IAS Indicatedairspeedin[kts]

Vs Calculated2 stall speed (static) of SR20 in [kts] for the respective configuration

consideringloadfactor

Vfe/Vno IndicatesVfedependingonactualflapsconfigurationorVno 2ReferencestallspeedappliedforDiagram2-1toDiagram2-24(for0°bank)acc.POH-SR20(2015):69KIAS(forflaps0),65KIAS(forflaps50%),60KIAS(forflaps100%)(rf.(POH-SR202015,p.5-12)).

TUGrazIMasterthesis


6

ThefollowingTable2-1summarizestheATCtransmissionsfrominitialATCcontactuntilthefirstgo-

aroundasretrievedfromtheHOUTowerAccidentPackageN4252G(2018).

CDT COM ATCTransmission/Note RY12:52:47 52G ThepilotcontactedtheHOUtowerLCpositionat1252:47andreportedat1600ft. 4

12:53:04 LCT Thetrainee(LCT)missedthesourceofthecallandthoughtitwasaSouthwestAirlines(SWA)flight.HerespondedasiftheSWApilothadcalled,thenrealizedthatithadactuallybeenthepilotofN4252G.

4

12:53:12 LCT Afterresolvingtheconfusion,theLCTtransmitted,“…you’renumber2followinga737ona3milefinal,cautionwaketurbulence,runway4clearedtoland”.

4

12:53:20 52G “WewillberunwayuhnumbertwofollowingtheBoeingrunway4clearedtoland…” 4

12:53:25 LCT “yesma'amandsayparking” 4

12:53:28 52G “We'llbeparkingMillionAir4252G” 4

12:53:51 LCI “Cirrus4252Gproceeddirecttothenumbers,you’regoingtobeinsidea737interceptinga10milefinal”

4

12:54:00 52G “OKyouwouldlikemetoproceedtothenumbers4252G” 4

12:54:04 LCI “November52G,whatdidapproachtellyoubefore?” 4

12:54:09 52G “Uh,tolandleftbaserunway4andfollowtheBoeing,4252G” 4

12:54:16 LCI “...proceeddirectthenumbersforrunway4,directtoHobby” 4

12:54:21 52G “DirecttoHobby,4252G” 4

12:54:24 I90 TheHobbyFinalcontrollercalledtheLCcontrollerstoaskthattheyhavetheCirrusproceeddirecttothenumbers,andtheLCIcontrollerrespondedthatthepilothadbeendirectedtodoso.

4

12:54:39 LCT TheLCTcontrolleraskedthepilottomaintainmaximumforwardspeedandproceeddirecttothenumbers,advisingherthattherewasa737on9milefinalfollowingtheCirrusthatwasovertakingitby80kts.Thepilotrespondedthatshewouldproceeddirecttothenumbersandkeepherspeedup.

4

12:55:49 LCT ThecontrollerbroadcastedtoallaircraftthatHOUATISinformationIndiawascurrent,altimeter29.94.ThepilotwasnotrequiredtoacknowledgetheupdatedATISannouncementanddidnotdoso.

4

12:55:59 LCT SWA235contactedHOU,reportingthattheywereon5milefinalforrunway4.TheLCTcontrollerrespondedthattheywerenumber2followingaCirruson2milefinal,clearedthepilottoland,andinstructedhimtoslowtofinalapproachspeed.

4

12:56:19 LCT windcheckof“080degreesat13ktsgustingto18kts”wasbroadcasted 4

12:57:02 LCI “justgo-aroundandflyrunwayheadingfornow,maintainVFR,andI’mgoingtoputyoubackonthedownwindforrunway35.Thewindsare090at13gusts18[kt].Canyouacceptrunway35?”

4

(rf.(HOU-ATCT-0064,2018,p.42,43,44)).

Table2-1SummaryofATCtransmissions,12:52:47-12:57:02CDT

Diagram2-1Visualdescentangledirecttotheaimingpoint,12:27:56-12:56:30CDT

0,00

2,00

4,00

6,00

8,00

10,00

12:27:56

12:30:08

12:30:56

12:31:44

12:32:32

12:33:20

12:34:08

12:34:56

12:35:56

12:36:56

12:37:44

12:38:32

12:39:32

12:40:20

12:42:07

12:43:19

12:44:19

12:45:31

12:46:19

12:47:07

12:47:55

12:48:43

12:49:31

12:50:42

12:51:30

12:52:18

12:53:18

12:54:06

12:54:54

12:55:42

12:56:30

Ry4-Path Ry35-Path

TUGrazIMasterthesis


7

Diagram2-2Graphicaldepictionofbasicflightdata,12:27:48-12:56:32CDT

-45-30-150153045

12:27:48

12:28:32

12:29:17

12:30:03

12:30:46

12:31:30

12:32:13

12:32:55

12:33:41

12:34:24

12:35:10

12:35:58

12:36:43

12:37:33

12:38:21

12:39:05

12:39:54

12:40:48

12:41:46

12:42:31

12:43:16

12:44:06

12:44:52

12:45:36

12:46:19

12:47:05

12:47:47

12:48:30

12:49:13

12:49:57

12:50:41

12:51:24

12:52:07

12:52:51

12:53:34

12:54:17

12:55:02

12:55:45

12:56:32

Pitch

-45-30-150153045

12:27:48

12:28:32

12:29:17

12:30:03

12:30:46

12:31:30

12:32:13

12:32:55

12:33:41

12:34:24

12:35:10

12:35:58

12:36:43

12:37:33

12:38:21

12:39:05

12:39:54

12:40:48

12:41:46

12:42:31

12:43:16

12:44:06

12:44:52

12:45:36

12:46:19

12:47:05

12:47:47

12:48:30

12:49:13

12:49:57

12:50:41

12:51:24

12:52:07

12:52:51

12:53:34

12:54:17

12:55:02

12:55:45

12:56:32

Roll

0

50

100

12:27:48

12:28:32

12:29:17

12:30:03

12:30:46

12:31:30

12:32:13

12:32:55

12:33:41

12:34:24

12:35:10

12:35:58

12:36:43

12:37:33

12:38:21

12:39:05

12:39:54

12:40:48

12:41:46

12:42:31

12:43:16

12:44:06

12:44:52

12:45:36

12:46:19

12:47:05

12:47:47

12:48:30

12:49:13

12:49:57

12:50:41

12:51:24

12:52:07

12:52:51

12:53:34

12:54:17

12:55:02

12:55:45

12:56:32

Power

0

1

2

12:27:48

12:28:32

12:29:17

12:30:03

12:30:46

12:31:30

12:32:13

12:32:55

12:33:41

12:34:24

12:35:10

12:35:58

12:36:43

12:37:33

12:38:21

12:39:05

12:39:54

12:40:48

12:41:46

12:42:31

12:43:16

12:44:06

12:44:52

12:45:36

12:46:19

12:47:05

12:47:47

12:48:30

12:49:13

12:49:57

12:50:41

12:51:24

12:52:07

12:52:51

12:53:34

12:54:17

12:55:02

12:55:45

12:56:32

Flaps

0

2000

4000

6000

12:27:48

12:28:32

12:29:17

12:30:03

12:30:46

12:31:30

12:32:13

12:32:55

12:33:41

12:34:24

12:35:10

12:35:58

12:36:43

12:37:33

12:38:21

12:39:05

12:39:54

12:40:48

12:41:46

12:42:31

12:43:16

12:44:06

12:44:52

12:45:36

12:46:19

12:47:05

12:47:47

12:48:30

12:49:13

12:49:57

12:50:41

12:51:24

12:52:07

12:52:51

12:53:34

12:54:17

12:55:02

12:55:45

12:56:32

AltB HOUelevauon

40,0

60,0

80,0

100,0

120,0

140,0

160,0

180,0

12:27:48

12:28:32

12:29:17

12:30:03

12:30:46

12:31:30

12:32:13

12:32:55

12:33:41

12:34:24

12:35:10

12:35:58

12:36:43

12:37:33

12:38:21

12:39:05

12:39:54

12:40:48

12:41:46

12:42:31

12:43:16

12:44:06

12:44:52

12:45:36

12:46:19

12:47:05

12:47:47

12:48:30

12:49:13

12:49:57

12:50:41

12:51:24

12:52:07

12:52:51

12:53:34

12:54:17

12:55:02

12:55:45

12:56:32

IAS Vs Vfe/Vno

TUGrazIMasterthesis


8

The detailed analysis of the flight data and the graphical presentation of the aircraft’s flight

parametersinDiagrams2-1(12:27:56-12:56:30CDT)and2-2(12:27:48-12:56:32CDT)inrelation

totheATCtranscript inTable2-1(12:52:47-12:57:02CDT)forthefirstapproachofN4252Gwere

analysedindetail.

Itrevealsthatbetween12:35:34CDTand12:36:27CDTtheVnowasexceededbyupto3.7kts.This

is permitted in smooth flight conditions. As the conditions of turbulence could not be extracted,

exceeding the Vno cannot be considered as an unsafe control action. At 12:55:23 CDT, the pilot

selected the flaps to50%ataspeedof129.5KIAS, therebyexceedingVfeof119KIASby10.5kts.

Until12:55:28CDT, theVfe limitwasexceeded (considering theATC request to “keepspeedup”).

When selecting the flaps to 100% at 12:55:47 CDT, Vfe was exceeded by 2kts for 1 second. The

aircraft’s final approach speed was gradually decreasing but not deceeding the normal approach

speeds (83KIAS for flaps50%,78KIAS for flaps100%, forproceduraldetails refer toEAppendix),

which - togetherwith theminor flight path corrections and the visual descent angle of around 3

degreestotheaimingpointofrunway4-concludedthatstabilizedapproachcriteriawerefulfilled.

AccordingtotheCirrusEnvelopeofSafety(refertoLAppendix,Figure6-3EnvelopeofSafety),the

reportedwind (“080 degrees at 13kts gusting to 18kts”) exceeded3 the personalized x-wind limit

(windlimit15kts,x-windlimit5kts,maximumgust5kts)accordingtothePilot’sCapabilityCategory

(fordetails,refertoDAppendix).

3TheauthorofthisthesisrecalculatedthewindcomponentsconsideringFigure6-4Windcomponentdiagramasfollows:080°/13ktssteady(gustsupto18kts)equals10kts(gustsupto14kts)headwindand8kts(gustsupto11kt)crosswindforrunway4(041°runwaytrack).

TUGrazIMasterthesis


9


Figure2-2Initialapproachtorunway4andATC-directedgo-around


0,00

5,00

10,00

15,00

20,00

25,00

12:56:54 12:57:06 12:57:18 12:57:31 12:57:43 12:57:55 12:58:07

Ry4-Path Ry35-Path

TUGrazIMasterthesis


10


-45

-30

-15

0

15

30

4512:57:02

12:57:04

12:57:06

12:57:09

12:57:11

12:57:13

12:57:16

12:57:18

12:57:20

12:57:23

12:57:25

12:57:27

12:57:30

12:57:32

12:57:35

12:57:38

12:57:40

12:57:43

12:57:45

12:57:47

12:57:50

12:57:52

12:57:55

12:57:57

12:57:59

12:58:02

12:58:04

12:58:06

Pitch Roll

0

20

40

60

80

100

12:57:02

12:57:04

12:57:06

12:57:09

12:57:11

12:57:13

12:57:16

12:57:18

12:57:20

12:57:23

12:57:25

12:57:27

12:57:30

12:57:32

12:57:35

12:57:38

12:57:40

12:57:43

12:57:45

12:57:47

12:57:50

12:57:52

12:57:55

12:57:57

12:57:59

12:58:02

12:58:04

12:58:06

Power

0

1

2

12:57:02

12:57:04

12:57:06

12:57:09

12:57:11

12:57:13

12:57:16

12:57:18

12:57:20

12:57:23

12:57:25

12:57:27

12:57:30

12:57:32

12:57:35

12:57:38

12:57:40

12:57:43

12:57:45

12:57:47

12:57:50

12:57:52

12:57:55

12:57:57

12:57:59

12:58:02

12:58:04

12:58:06

Flaps

0

500

1000

1500

12:57:02

12:57:04

12:57:06

12:57:09

12:57:11

12:57:13

12:57:16

12:57:18

12:57:20

12:57:23

12:57:25

12:57:27

12:57:30

12:57:32

12:57:35

12:57:38

12:57:40

12:57:43

12:57:45

12:57:47

12:57:50

12:57:52

12:57:55

12:57:57

12:57:59

12:58:02

12:58:04

12:58:06

AltB HOUelevauon

40,0

90,0

140,0

12:57:02

12:57:04

12:57:06

12:57:09

12:57:11

12:57:13

12:57:16

12:57:18

12:57:20

12:57:23

12:57:25

12:57:27

12:57:30

12:57:32

12:57:35

12:57:38

12:57:40

12:57:43

12:57:45

12:57:47

12:57:50

12:57:52

12:57:55

12:57:57

12:57:59

12:58:02

12:58:04

12:58:06

IAS Vs Vfe/Vno

TUGrazIMasterthesis


11

Thedetailedanalysisof the flightdataand thegraphicalpresentationsof the flight trackwith the

associated ATC transcript in Figure 2-2 and the graphical presentation of the aircraft’s flight

parametersinDiagrams2-3(12:56:54-12:58:07CDT)and2-4(12:57:02-12:58:06CDT)inrelation

totheATCtranscriptfortheinitialapproachofN4252Gtorunway4wereanalysedindetail.

ItrevealsthattheapproachwascancelledbyATCat12:57:01byrequestingN4252Gtogo-around.

Uptothen,theaircrafthadbeenfulfillingstabilizedapproachcriteriaforlandingonrunway4.When

initiatingthego-around,maximumpowerforthego-aroundprocedurewasnotset(forprocedural

details, refer to E Appendix), which the author assumes as the pilot’s intention to maintain the

presentaltitude(AltB)ofapproximately500ftandavoidoverspeedconditionswithexcessivepower.

The flapswere retracted to 50% at 75 KIAS and to 0% at 83 KIAS,which iswithin safe limits and

accordingtothePOHprocedures(forproceduraldetails,refertoEAppendix).Questioningtheright

downwind for runway 35 at 12:57:48 CDT by the pilot shows that uncertainty about the ATC

intentionswaspresent.

TUGrazIMasterthesis


12


Figure2-3Maneuversfollowingtheinitialgo-around


0,00

5,00

10,00

15,00

20,00

12:57:55 12:58:07 12:58:19 12:58:31 12:58:43 12:58:55 12:59:07

Ry4-Path Ry35-Path

TUGrazIMasterthesis


13


-45

-30

-15

0

15

30

4512:58:04

12:58:06

12:58:09

12:58:11

12:58:13

12:58:16

12:58:18

12:58:21

12:58:23

12:58:25

12:58:28

12:58:30

12:58:32

12:58:35

12:58:37

12:58:39

12:58:42

12:58:44

12:58:47

12:58:49

12:58:51

12:58:54

12:58:56

12:59:00

12:59:02

12:59:04

Pitch Roll

0

20

40

60

80

100

12:58:04

12:58:06

12:58:09

12:58:11

12:58:13

12:58:16

12:58:18

12:58:21

12:58:23

12:58:25

12:58:28

12:58:30

12:58:32

12:58:35

12:58:37

12:58:39

12:58:42

12:58:44

12:58:47

12:58:49

12:58:51

12:58:54

12:58:56

12:59:00

12:59:02

12:59:04

Power

0

1

2

12:58:04

12:58:06

12:58:09

12:58:11

12:58:13

12:58:16

12:58:18

12:58:21

12:58:23

12:58:25

12:58:28

12:58:30

12:58:32

12:58:35

12:58:37

12:58:39

12:58:42

12:58:44

12:58:47

12:58:49

12:58:51

12:58:54

12:58:56

12:59:00

12:59:02

12:59:04

Flaps

0

500

1000

1500

12:58:04

12:58:06

12:58:09

12:58:11

12:58:13

12:58:16

12:58:18

12:58:21

12:58:23

12:58:25

12:58:28

12:58:30

12:58:32

12:58:35

12:58:37

12:58:39

12:58:42

12:58:44

12:58:47

12:58:49

12:58:51

12:58:54

12:58:56

12:59:00

12:59:02

12:59:04

AltB HOUelevauon

40,0

90,0

140,0

12:58:04

12:58:06

12:58:09

12:58:11

12:58:13

12:58:16

12:58:18

12:58:21

12:58:23

12:58:25

12:58:28

12:58:30

12:58:32

12:58:35

12:58:37

12:58:39

12:58:42

12:58:44

12:58:47

12:58:49

12:58:51

12:58:54

12:58:56

12:59:00

12:59:02

12:59:04

IAS Vs Vfe/Vno

TUGrazIMasterthesis


14



parameters in Diagrams 2-5 (12:57:55 - 12:59:07 CDT) and 2-6 (12:58:04 - 12:59:04 CDT) for the

maneuversfollowingtheinitialgo-aroundofN4252Grevealsthatnounsafecontrolactionshadbeen

performedbythepilot.

TUGrazIMasterthesis


15


Figure2-4Continuedpatternmaneuvers


0,00

5,00

10,00

15,00

12:58:55 12:59:07 12:59:18 12:59:30 12:59:42 12:59:54 13:00:06

Ry4-Path Ry35-Path

TUGrazIMasterthesis


16


-45

-30

-15

0

15

30

4512:59:05

12:59:08

12:59:10

12:59:13

12:59:15

12:59:17

12:59:20

12:59:22

12:59:24

12:59:27

12:59:29

12:59:32

12:59:34

12:59:36

12:59:39

12:59:41

12:59:43

12:59:46

12:59:48

12:59:51

12:59:53

12:59:55

12:59:58

13:00:00

Pitch Roll

0

20

40

60

80

100

12:59:05

12:59:08

12:59:10

12:59:13

12:59:15

12:59:17

12:59:20

12:59:22

12:59:24

12:59:27

12:59:29

12:59:32

12:59:34

12:59:36

12:59:39

12:59:41

12:59:43

12:59:46

12:59:48

12:59:51

12:59:53

12:59:55

12:59:58

13:00:00

Power

0

1

2

12:59:05

12:59:08

12:59:10

12:59:13

12:59:15

12:59:17

12:59:20

12:59:22

12:59:24

12:59:27

12:59:29

12:59:32

12:59:34

12:59:36

12:59:39

12:59:41

12:59:43

12:59:46

12:59:48

12:59:51

12:59:53

12:59:55

12:59:58

13:00:00

Flaps

0

500

1000

1500

12:59:05

12:59:08

12:59:10

12:59:13

12:59:15

12:59:17

12:59:20

12:59:22

12:59:24

12:59:27

12:59:29

12:59:32

12:59:34

12:59:36

12:59:39

12:59:41

12:59:43

12:59:46

12:59:48

12:59:51

12:59:53

12:59:55

12:59:58

13:00:00

AltB HOUelevauon

40,0

90,0

140,0

12:59:05

12:59:08

12:59:10

12:59:13

12:59:15

12:59:17

12:59:20

12:59:22

12:59:24

12:59:27

12:59:29

12:59:32

12:59:34

12:59:36

12:59:39

12:59:41

12:59:43

12:59:46

12:59:48

12:59:51

12:59:53

12:59:55

12:59:58

13:00:00

IAS Vs Vfe/Vno

TUGrazIMasterthesis


17



parameters in Diagrams 2-7 (12:58:55 - 13:00:06 CDT) and 2-8 (12:59:05 - 13:00:00 CDT) for the

continuedpatternmaneuversofN4252Gwereanalysedindetail.

It reveals that between 12:59:22 and 12:59:56 CDT the bank angle was rapidly changing from a

wings-levelflightviaaleftrollof34degreesuptoarightsteepturn4of46degrees.

TheAOPAwebsite (2019) states that flyinga visual pattern shouldbe limited toamaximumbank

angle of 30 degrees (rf. (AOPA.org retrieved from https://www.aopa.org/training-and-

safety/Students/presolo/skills/entering-the-traffic-pattern,2019)).

Thenon-standardphraseology5(“leftheading30degrees”insteadof“turnleftheading030degrees”

or “turn left by 30degrees”) at 12:59:20CDTand runway assignment changes throughATC (from

runway35torunway4andbacktorunway35)withinlessthan1minute(12:58:57CDT–12:59:47

CDT).

4In visual flight turns exceeding 45 degrees of bank are defined as “steep turns” (rf. (US Department ofTransportation,Pilot’sHandbookofAeronauticalKnowledge,2016,G29)).5StandardATCPhraseologiesforVectorstoFinalApproacharedefinedinICAODocument9432(2007),ManualofRadiotelephony,Chapter7.5

TUGrazIMasterthesis


18


Figure2-5Continuedpatternmaneuvers


0,00

1,00

2,00

3,00

4,00

12:59:54 13:00:06 13:00:18 13:00:30 13:00:42 13:00:54

Ry4-Path Ry35-Path

TUGrazIMasterthesis


19


-45

-30

-15

0

15

30

4512:59:59

13:00:00

13:00:01

13:00:02

13:00:04

13:00:05

13:00:06

13:00:07

13:00:08

13:00:10

13:00:11

13:00:12

13:00:13

13:00:14

13:00:16

13:00:17

13:00:18

13:00:19

13:00:20

13:00:22

13:00:23

13:00:24

13:00:25

13:00:26

13:00:29

13:00:30

13:00:31

13:00:32

13:00:33

13:00:35

13:00:36

13:00:37

13:00:38

13:00:39

13:00:41

13:00:42

13:00:43

13:00:45

13:00:47

Pitch Roll

0

20

40

60

80

100

12:59:59

13:00:00

13:00:01

13:00:02

13:00:04

13:00:05

13:00:06

13:00:07

13:00:08

13:00:10

13:00:11

13:00:12

13:00:13

13:00:14

13:00:16

13:00:17

13:00:18

13:00:19

13:00:20

13:00:22

13:00:23

13:00:24

13:00:25

13:00:26

13:00:29

13:00:30

13:00:31

13:00:32

13:00:33

13:00:35

13:00:36

13:00:37

13:00:38

13:00:39

13:00:41

13:00:42

13:00:43

13:00:45

13:00:47

Power

0

1

2

12:59:59

13:00:00

13:00:01

13:00:02

13:00:04

13:00:05

13:00:06

13:00:07

13:00:08

13:00:10

13:00:11

13:00:12

13:00:13

13:00:14

13:00:16

13:00:17

13:00:18

13:00:19

13:00:20

13:00:22

13:00:23

13:00:24

13:00:25

13:00:26

13:00:29

13:00:30

13:00:31

13:00:32

13:00:33

13:00:35

13:00:36

13:00:37

13:00:38

13:00:39

13:00:41

13:00:42

13:00:43

13:00:45

13:00:47

Flaps

0

500

1000

1500

12:59:59

13:00:00

13:00:01

13:00:02

13:00:04

13:00:05

13:00:06

13:00:07

13:00:08

13:00:10

13:00:11

13:00:12

13:00:13

13:00:14

13:00:16

13:00:17

13:00:18

13:00:19

13:00:20

13:00:22

13:00:23

13:00:24

13:00:25

13:00:26

13:00:29

13:00:30

13:00:31

13:00:32

13:00:33

13:00:35

13:00:36

13:00:37

13:00:38

13:00:39

13:00:41

13:00:42

13:00:43

13:00:45

13:00:47

AltB HOUelevauon

40,0

90,0

140,0

12:59:59

13:00:00

13:00:01

13:00:02

13:00:04

13:00:05

13:00:06

13:00:07

13:00:08

13:00:10

13:00:11

13:00:12

13:00:13

13:00:14

13:00:16

13:00:17

13:00:18

13:00:19

13:00:20

13:00:22

13:00:23

13:00:24

13:00:25

13:00:26

13:00:29

13:00:30

13:00:31

13:00:32

13:00:33

13:00:35

13:00:36

13:00:37

13:00:38

13:00:39

13:00:41

13:00:42

13:00:43

13:00:45

13:00:47

IAS Vs Vfe/Vno

TUGrazIMasterthesis


20



parameters inDiagrams 2-9 (12:59:54 - 13:00:54 CDT) and 2-10 (12:59:59 - 13:00:47 CDT) for the

continuedpatternmaneuversofN4252Gwereanalysedindetail.

Itrevealsthatat13:00:14CDTtheATCwasuncertaininwhichdirectionN4252Gwasturning.After

clarificationthepilotwasclearedbyATCforatightturn(“keepittight,Ineedyoutomakeittight”),

whichisanon-standardICAOphraseology.Thefollowingbankanglewasincreasedtoamaximumof

50degreesat13:00:30CDT,whichreducedthestallspeedmargin6to15kts.

At13:00:42, theaircraftwasataposition (altitude998 ft,direct visualdescentangle2.92°, speed

107 KIAS, approximately7 15 degrees left of centerline) suitable for landing at runway 35. For an

unknownreason,thepilotadvisedATCaboutheruncertaintyofbeingcorrectlylinedupforrunway

35, most probably due a severe degradation of situational awareness due to the high workload

situation. At 13:00:47 CDT, ATC cleared the pilot to turn right (without any heading assignment,

whichisnotincompliancewithICAOstandardphraseology)andaclimbto1600ft8.

6asdifferencebetweenIASandVsin[kts]7measuredbytheauthorwithGoogleEarthProApplication,consideringtheN4252GRadarTargetFile-HOUASR Google Earth KML Target File as retrieved from NTSB DMS Website:https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB8Author’snote:ATCclearancetoclimbto1600ftaboveMSL(consideringHOUairportelevationof43ftaboveMSL)seemsunusualhighforexpectingtokeepasingleengineaircraftvisuallyinanairport’strafficpattern.

TUGrazIMasterthesis


21


Figure2-6Changingapproachfromrunway4torunway35


0,00

2,00

4,00

6,00

8,00

10,00

12,00

13:00:42 13:00:54 13:01:06 13:01:18 13:01:30 13:01:42

Ry4-Path Ry35-Path

TUGrazIMasterthesis


22


-45

-30

-15

0

15

30

4513:00:47

13:00:49

13:00:51

13:00:54

13:00:56

13:00:59

13:01:01

13:01:05

13:01:07

13:01:11

13:01:13

13:01:16

13:01:19

13:01:21

13:01:24

13:01:26

13:01:28

13:01:31

13:01:33

13:01:36

13:01:38

13:01:40

13:01:43

13:01:45

13:01:48

13:01:50

13:01:52

Pitch Roll

0

20

40

60

80

100

13:00:47

13:00:49

13:00:51

13:00:54

13:00:56

13:00:59

13:01:01

13:01:05

13:01:07

13:01:11

13:01:13

13:01:16

13:01:19

13:01:21

13:01:24

13:01:26

13:01:28

13:01:31

13:01:33

13:01:36

13:01:38

13:01:40

13:01:43

13:01:45

13:01:48

13:01:50

13:01:52

Power

0

1

2

13:00:47

13:00:49

13:00:51

13:00:54

13:00:56

13:00:59

13:01:01

13:01:05

13:01:07

13:01:11

13:01:13

13:01:16

13:01:19

13:01:21

13:01:24

13:01:26

13:01:28

13:01:31

13:01:33

13:01:36

13:01:38

13:01:40

13:01:43

13:01:45

13:01:48

13:01:50

13:01:52

Flaps

0

500

1000

1500

13:00:47

13:00:49

13:00:51

13:00:54

13:00:56

13:00:59

13:01:01

13:01:05

13:01:07

13:01:11

13:01:13

13:01:16

13:01:19

13:01:21

13:01:24

13:01:26

13:01:28

13:01:31

13:01:33

13:01:36

13:01:38

13:01:40

13:01:43

13:01:45

13:01:48

13:01:50

13:01:52

AltB HOUelevauon

40,0

90,0

140,0

13:00:47

13:00:49

13:00:51

13:00:54

13:00:56

13:00:59

13:01:01

13:01:05

13:01:07

13:01:11

13:01:13

13:01:16

13:01:19

13:01:21

13:01:24

13:01:26

13:01:28

13:01:31

13:01:33

13:01:36

13:01:38

13:01:40

13:01:43

13:01:45

13:01:48

13:01:50

13:01:52

IAS Vs Vfe/Vno

TUGrazIMasterthesis


23



parameters inDiagrams2-11 (13:00:42 -13:01:42CDT)and2-12 (13:00:47 -13:01:52CDT) for the

patternmaneuversofN4252Gwhentheapproachwaschangedfromrunway4torunway35were

analysedindetail.

Itrevealsthatforthediscontinuedapproachthepowerwasincreasedfrom53%to82%at13:00:57

CDT. As the flapswere not extended themissed approach procedurewas performedwithout the

requirement to retract the flaps. The airspeed at the time of themissed approachwas 114 KIAS.

From13:01:33CDTtill13:01:37CDTthebankanglewasexceeding40degrees.At13:01:29CDTATC

advisedtomakearightturn“all thewayaround”torunway35,whilethepilotwas increasingthe

bankangleupto42degrees(at13:01:33CDT)inarightturn.At13:01:42CDTtheaircraftwasona

visualdescentangletotheaimingpointofrunway35of10.9degrees(notethatthePAPIforrunway

35wascalibrated for3.0degrees) ina rightbanking turnof32degrees.At13:01:46CDTthepilot

selectedtheflapsto50%withaspeedof117KIAS(2ktsbelowVfe)inarightturnwithabankangle

of25degrees.

TUGrazIMasterthesis


24


Figure2-7Settingupforinitialstraight-inapproachtorunway35


0,00

5,00

10,00

15,00

13:01:42 13:01:54 13:02:06 13:02:18 13:02:30 13:02:42 13:02:54

Ry4-Path Ry35-Path

TUGrazIMasterthesis


25


-45

-30

-15

0

15

30

4513:01:52

13:01:55

13:01:57

13:02:00

13:02:02

13:02:04

13:02:07

13:02:09

13:02:12

13:02:14

13:02:17

13:02:19

13:02:21

13:02:24

13:02:26

13:02:30

13:02:32

13:02:35

13:02:37

13:02:39

13:02:42

13:02:44

13:02:47

13:02:49

13:02:52

Pitch Roll

0

20

40

60

80

100

13:01:52

13:01:55

13:01:57

13:02:00

13:02:02

13:02:04

13:02:07

13:02:09

13:02:12

13:02:14

13:02:17

13:02:19

13:02:21

13:02:24

13:02:26

13:02:30

13:02:32

13:02:35

13:02:37

13:02:39

13:02:42

13:02:44

13:02:47

13:02:49

13:02:52

Power

0

1

2

13:01:52

13:01:55

13:01:57

13:02:00

13:02:02

13:02:04

13:02:07

13:02:09

13:02:12

13:02:14

13:02:17

13:02:19

13:02:21

13:02:24

13:02:26

13:02:30

13:02:32

13:02:35

13:02:37

13:02:39

13:02:42

13:02:44

13:02:47

13:02:49

13:02:52

Flaps

0

500

1000

1500

13:01:52

13:01:55

13:01:57

13:02:00

13:02:02

13:02:04

13:02:07

13:02:09

13:02:12

13:02:14

13:02:17

13:02:19

13:02:21

13:02:24

13:02:26

13:02:30

13:02:32

13:02:35

13:02:37

13:02:39

13:02:42

13:02:44

13:02:47

13:02:49

13:02:52

AltB HOUelevauon

40,0

60,0

80,0

100,0

120,0

13:01:52

13:01:55

13:01:57

13:02:00

13:02:02

13:02:04

13:02:07

13:02:09

13:02:12

13:02:14

13:02:17

13:02:19

13:02:21

13:02:24

13:02:26

13:02:30

13:02:32

13:02:35

13:02:37

13:02:39

13:02:42

13:02:44

13:02:47

13:02:49

13:02:52

IAS Vs Vfe/Vno

TUGrazIMasterthesis


26

TheflightdataandthegraphicalpresentationsoftheflighttrackwiththeassociatedATCtranscript

in Figure 2-7 and the graphical presentation of the aircraft’s flight parameters in Diagrams 2-13

(13:01:42-13:02:54CDT)and2-14(13:01:52-13:02:52CDT)forthesetupofN4252Gfortheinitial

straight-inapproachtorunway35wereanalysedindetail.

At13:02:00CDT, theATCadvised thepilot “lookinggood to start thedescent to runway35”. The

aircraftwasatapositionwith5.7degreesvisualdescentangletorunway35,atanaltitudeAltBof

1117ftwith95KIAS,stillclimbingwitha35degreesbankangle.

At13:02:12CDT,whenthepilotreportedtherunwayinsighttheaircraftwasatapositionwith6.0

degreesvisualdescentangletorunway35(notethatthePAPIforrunway35wascalibratedfor3.0

degrees),withanairspeedof82.4KIAS,turningrightinasteepturnof46degreesofbankangle.The

highbankanglereducedthestallspeedmarginto4kts.Therefore,itcanbeassumedthatthestall

warningwastriggered9.Thepilotsubsequentlyreducedtheangleofpitchandrollandthestallspeed

marginincreased.At13:02:15CDT,theflapswereextendedto100%whilstturningrightwithabank

angleof37degrees.

At13:02:24CDT,thepowerwasreducedtoidlewithin5seconds.Simultaneously,ATCadvisedthe

landingclearanceandtheactualwindof100degreesat15ktswithgusts to20kts forrunway35.

AccordingtotheCirrusEnvelopeofSafety(refertoLAppendix,Figure6-3EnvelopeofSafety),the

reportedwindwas exceeding10 the personalized x-wind limit (wind limit 15kts, x-wind limit 5kts,

maximumgust5kts)accordingtothePilot’sCapabilityCategory(fordetails,refertoDAppendix).

At 13:02:29, the pilot advised to ATC “trying to lose altitude”. The initiated descent rate for a

stabilizedapproachtotheaimingpointofrunway35wasnotsufficientandthevisualdescentangle

further increased.At13:02:54,CDTthevisualdescentangle to theaimingpointof runway35was

12.0degrees,farabovethenominalPAPIangleof3.0degrees.

9“thestallspeedwarninghornsound[s]between5and10ktsbeforethestall”(POH-SR20,2015,p.4-23).FortheprevailinganalysistheauthorhasanticipatedthatstallwarningtriggersifIAS<(Vs+5kts).10TheauthorofthisthesisrecalculatedthewindcomponentsconsideringFigure6-4Windcomponentdiagramasfollows:100°/15ktssteady(gustsupto20kts)equals4kts(gustsupto5kts)tailwindand15kts(gustsupto19kts)crosswindforrunway35(356°runwaytrack).

TUGrazIMasterthesis


27


Figure2-8Runway35firstapproachandgo-around


0,00

5,00

10,00

15,00

20,00

25,00

30,00

13:02:54 13:03:07 13:03:19 13:03:31 13:03:43 13:03:55 13:04:07

Ry4-Path Ry35-Path

TUGrazIMasterthesis


28


-45

-30

-15

0

15

30

4513:02:53

13:02:55

13:02:58

13:03:00

13:03:02

13:03:05

13:03:07

13:03:10

13:03:12

13:03:15

13:03:17

13:03:19

13:03:22

13:03:24

13:03:27

13:03:29

13:03:32

13:03:34

13:03:36

13:03:39

13:03:41

13:03:44

13:03:46

13:03:50

13:03:52

13:03:55

13:03:57

Pitch Roll

0

20

40

60

80

100

13:02:53

13:02:55

13:02:58

13:03:00

13:03:02

13:03:05

13:03:07

13:03:10

13:03:12

13:03:15

13:03:17

13:03:19

13:03:22

13:03:24

13:03:27

13:03:29

13:03:32

13:03:34

13:03:36

13:03:39

13:03:41

13:03:44

13:03:46

13:03:50

13:03:52

13:03:55

13:03:57

Power

0

1

2

13:02:53

13:02:55

13:02:58

13:03:00

13:03:02

13:03:05

13:03:07

13:03:10

13:03:12

13:03:15

13:03:17

13:03:19

13:03:22

13:03:24

13:03:27

13:03:29

13:03:32

13:03:34

13:03:36

13:03:39

13:03:41

13:03:44

13:03:46

13:03:50

13:03:52

13:03:55

13:03:57

Flaps

0

500

1000

1500

13:02:53

13:02:55

13:02:58

13:03:00

13:03:02

13:03:05

13:03:07

13:03:10

13:03:12

13:03:15

13:03:17

13:03:19

13:03:22

13:03:24

13:03:27

13:03:29

13:03:32

13:03:34

13:03:36

13:03:39

13:03:41

13:03:44

13:03:46

13:03:50

13:03:52

13:03:55

13:03:57

AltB HOUelevauon

40,0

60,0

80,0

100,0

13:02:53

13:02:55

13:02:58

13:03:00

13:03:02

13:03:05

13:03:07

13:03:10

13:03:12

13:03:15

13:03:17

13:03:19

13:03:22

13:03:24

13:03:27

13:03:29

13:03:32

13:03:34

13:03:36

13:03:39

13:03:41

13:03:44

13:03:46

13:03:50

13:03:52

13:03:55

13:03:57

IAS Vs Vfe/Vno

TUGrazIMasterthesis


29



(13:02:54-13:04:07CDT)and2-16(13:02:53-13:03:57CDT)forthefirstapproachandgo-aroundof

N4252Gtorunway35wereanalysedindetail.

At 13:03:29 CDT, when the aiming point of runway 35 was already overflown and the pilot still

seemedtointendtolandonrunway35,ATCadvisedthepilotabouttheaircraft’shighposition(“you

might be too high”). The pilot initiated a go-around at 13:03:34 CDT. The power was not set to

maximumpower(forproceduraldetails,refertoEAppendix).Theairspeedwasat64.1KIAS,when

theflapswereretractedto50%at13:03:36CDT.Thestallspeedmargindecreasedto2ktswithan

activestallwarning11.ATCadvisedat13:03:43CDTthatthepilotshouldexpectarighttrafficpattern

forrunway35.

At13:03:46CDT,atanaltitudeof192fttheflapswereretractedto0%at68.7KIAS(wellbelowthe

recommendedspeedof83KIAS)withastallspeedmarginof4ktsandthepowersetto77%instead

ofmaximumpower (forproceduraldetails, refer toEAppendix). Thepitchanglewasnot reduced

and the speed furtherdecreaseduntil reaching the stall speedat13:03:49CDT.Subsequently, the

pitchanglewasslightlyreducedandtheaircraftleftthespeedregimetriggeringastallwarningatan

altitudeof183ftat13:03:56CDTwithapositivespeedtrend.

11“thestallspeedwarninghornsound[s]between5and10ktsbeforethestall”(POH-SR20,2015,p.4-23).FortheprevailinganalysistheauthorhasanticipatedthatstallwarningtriggersifIAS<(Vs+5kts).

TUGrazIMasterthesis


30


Figure2-9Preparingforsecondapproachtorunway35


0,00

5,00

10,00

15,00

20,00

25,00

13:03:55 13:04:07 13:04:19 13:04:31 13:04:43 13:04:55 13:05:07 13:05:19 13:05:31 13:05:43 13:05:55

Ry4-Path Ry35-Path

TUGrazIMasterthesis


31


-45

-30

-15

0

15

30

4513:03:56

13:04:01

13:04:04

13:04:08

13:04:13

13:04:18

13:04:21

13:04:25

13:04:29

13:04:32

13:04:36

13:04:40

13:04:43

13:04:47

13:04:51

13:04:54

13:04:58

13:05:02

13:05:05

13:05:09

13:05:13

13:05:16

13:05:20

13:05:24

13:05:27

13:05:32

13:05:36

13:05:39

13:05:43

13:05:47

13:05:50

Pitch Roll

0

20

40

60

80

100

13:03:56

13:04:01

13:04:04

13:04:08

13:04:13

13:04:18

13:04:21

13:04:25

13:04:29

13:04:32

13:04:36

13:04:40

13:04:43

13:04:47

13:04:51

13:04:54

13:04:58

13:05:02

13:05:05

13:05:09

13:05:13

13:05:16

13:05:20

13:05:24

13:05:27

13:05:32

13:05:36

13:05:39

13:05:43

13:05:47

13:05:50

Power

0

1

2

13:03:56

13:04:01

13:04:04

13:04:08

13:04:13

13:04:18

13:04:21

13:04:25

13:04:29

13:04:32

13:04:36

13:04:40

13:04:43

13:04:47

13:04:51

13:04:54

13:04:58

13:05:02

13:05:05

13:05:09

13:05:13

13:05:16

13:05:20

13:05:24

13:05:27

13:05:32

13:05:36

13:05:39

13:05:43

13:05:47

13:05:50

Flaps

0

500

1000

1500

13:03:56

13:04:01

13:04:04

13:04:08

13:04:13

13:04:18

13:04:21

13:04:25

13:04:29

13:04:32

13:04:36

13:04:40

13:04:43

13:04:47

13:04:51

13:04:54

13:04:58

13:05:02

13:05:05

13:05:09

13:05:13

13:05:16

13:05:20

13:05:24

13:05:27

13:05:32

13:05:36

13:05:39

13:05:43

13:05:47

13:05:50

AltB HOUelevauon

40,0

60,0

80,0

100,0

120,0

13:03:56

13:04:01

13:04:04

13:04:08

13:04:13

13:04:18

13:04:21

13:04:25

13:04:29

13:04:32

13:04:36

13:04:40

13:04:43

13:04:47

13:04:51

13:04:54

13:04:58

13:05:02

13:05:05

13:05:09

13:05:13

13:05:16

13:05:20

13:05:24

13:05:27

13:05:32

13:05:36

13:05:39

13:05:43

13:05:47

13:05:50

IAS Vs Vfe/Vno

TUGrazIMasterthesis


32



(13:03:55 - 13:05:55 CDT) and 2-18 (13:03:56 - 13:05:50 CDT) whilst preparing for the second

approachofN4252Gtorunway35wereanalysedindetail.At13:04:39CDTtheATCadvisedtoenter

the right downwind for runway 35. As there was no other traffic reported for runway 4 by ATC,

properapplicationofriskassessmenthadresultedinrequestingrunway4toimprovetheprevailing

windconditionsforapproachandlanding.

At13:04:27,whilstina29degreebankedrightturnwithaspeedof74KIASthestallspeedmargin

was reduced to 4kts. Therefore, it can be assumed that the stall warning was triggered12 for 4

seconds.


TUGrazIMasterthesis


33


Figure2-10Downwindtofinalturn,secondapproachtorunway35


0,00

5,00

10,00

15,00

20,00

25,00

13:05:43 13:05:55 13:06:06 13:06:18 13:06:30 13:06:42 13:06:54 13:07:06

Ry4-Path Ry35-Path

TUGrazIMasterthesis


34


-45

-30

-15

0

15

30

4513:05:50

13:05:53

13:05:55

13:05:58

13:06:00

13:06:03

13:06:05

13:06:08

13:06:10

13:06:13

13:06:15

13:06:17

13:06:20

13:06:24

13:06:26

13:06:28

13:06:31

13:06:33

13:06:36

13:06:38

13:06:41

13:06:43

13:06:46

13:06:48

13:06:51

13:06:53

13:06:55

13:06:58

13:07:00

Pitch Roll

0

20

40

60

80

100

13:05:50

13:05:53

13:05:55

13:05:58

13:06:00

13:06:03

13:06:05

13:06:08

13:06:10

13:06:13

13:06:15

13:06:17

13:06:20

13:06:24

13:06:26

13:06:28

13:06:31

13:06:33

13:06:36

13:06:38

13:06:41

13:06:43

13:06:46

13:06:48

13:06:51

13:06:53

13:06:55

13:06:58

13:07:00

Power

0

1

2

13:05:50

13:05:53

13:05:55

13:05:58

13:06:00

13:06:03

13:06:05

13:06:08

13:06:10

13:06:13

13:06:15

13:06:17

13:06:20

13:06:24

13:06:26

13:06:28

13:06:31

13:06:33

13:06:36

13:06:38

13:06:41

13:06:43

13:06:46

13:06:48

13:06:51

13:06:53

13:06:55

13:06:58

13:07:00

Flaps

0

500

1000

1500

13:05:50

13:05:53

13:05:55

13:05:58

13:06:00

13:06:03

13:06:05

13:06:08

13:06:10

13:06:13

13:06:15

13:06:17

13:06:20

13:06:24

13:06:26

13:06:28

13:06:31

13:06:33

13:06:36

13:06:38

13:06:41

13:06:43

13:06:46

13:06:48

13:06:51

13:06:53

13:06:55

13:06:58

13:07:00

AltB HOUelevauon

40,0

60,0

80,0

100,0

120,0

13:05:50

13:05:53

13:05:55

13:05:58

13:06:00

13:06:03

13:06:05

13:06:08

13:06:10

13:06:13

13:06:15

13:06:17

13:06:20

13:06:24

13:06:26

13:06:28

13:06:31

13:06:33

13:06:36

13:06:38

13:06:41

13:06:43

13:06:46

13:06:48

13:06:51

13:06:53

13:06:55

13:06:58

13:07:00

IAS Vs Vfe/Vno

TUGrazIMasterthesis


35


in Figure 2-10 and the graphical presentation of the aircraft’s flight parameters in Diagram 2-19

(13:05:43-13:07:06CDT)and2-20(13:05:50-13:07:00CDT)whilstproceedingondownwindandto

the final turn for the secondapproach to runway35ofN4252Gwereanalysed indetail. Between

13:06:42and13:06:53CDT,whenturningonfinalforrunway35thebankanglewasincreasedupto

amaximumof51degrees.At13:06:55CDT,theflapswereextendedto50%andthepowerreduced

to idle,whilst the visual descent anglewas at 5.7 degrees (note that the PAPI for runway 35was

calibratedfor3.0degrees)with101.3KIASina31degreesofbankangleturn.

TUGrazIMasterthesis


36


Figure2-11Secondapproachtorunway35


0,00

5,00

10,00

15,00

20,00

25,00

30,00

13:06:54 13:07:06 13:07:18 13:07:30 13:07:43 13:07:55 13:08:07

Ry4-Path Ry35-Path

TUGrazIMasterthesis


37


-45

-30

-15

0

15

30

4513:06:59

13:07:02

13:07:04

13:07:08

13:07:10

13:07:13

13:07:15

13:07:17

13:07:20

13:07:22

13:07:25

13:07:27

13:07:30

13:07:32

13:07:35

13:07:37

13:07:40

13:07:42

13:07:45

13:07:47

13:07:49

13:07:52

13:07:54

13:07:57

13:07:59

Pitch Roll

0

20

40

60

80

100

13:06:59

13:07:02

13:07:04

13:07:08

13:07:10

13:07:13

13:07:15

13:07:17

13:07:20

13:07:22

13:07:25

13:07:27

13:07:30

13:07:32

13:07:35

13:07:37

13:07:40

13:07:42

13:07:45

13:07:47

13:07:49

13:07:52

13:07:54

13:07:57

13:07:59

Power

0

1

2

13:06:59

13:07:02

13:07:04

13:07:08

13:07:10

13:07:13

13:07:15

13:07:17

13:07:20

13:07:22

13:07:25

13:07:27

13:07:30

13:07:32

13:07:35

13:07:37

13:07:40

13:07:42

13:07:45

13:07:47

13:07:49

13:07:52

13:07:54

13:07:57

13:07:59

Flaps

0

500

1000

1500

13:06:59

13:07:02

13:07:04

13:07:08

13:07:10

13:07:13

13:07:15

13:07:17

13:07:20

13:07:22

13:07:25

13:07:27

13:07:30

13:07:32

13:07:35

13:07:37

13:07:40

13:07:42

13:07:45

13:07:47

13:07:49

13:07:52

13:07:54

13:07:57

13:07:59

AltB HOUelevauon

40,0

60,0

80,0

100,0

120,0

13:06:59

13:07:02

13:07:04

13:07:08

13:07:10

13:07:13

13:07:15

13:07:17

13:07:20

13:07:22

13:07:25

13:07:27

13:07:30

13:07:32

13:07:35

13:07:37

13:07:40

13:07:42

13:07:45

13:07:47

13:07:49

13:07:52

13:07:54

13:07:57

13:07:59

IAS Vs Vfe/Vno

TUGrazIMasterthesis


38



(13:06:54-13:08:07CDT)and2-22(13:06:59-13:07:59CDT)whilstperformingthesecondapproach

torunway35ofN4252Gwereanalysedindetail.

The power was set to idle at 13:07:02 CDT. At 13:07:05 CDT, the pilot of N4252G reported the

runway insight toATC.At13:07:10CDTATCadvised the landingclearanceandtheactualwindof

090degreesat13ktswithguststo18ktsforrunway35.AccordingtotheCirrusEnvelopeofSafety

(refer to L Appendix, Figure 6-3 Envelope of Safety), the reported wind was exceeding13 the

personalizedx-windlimit(windlimit15kts,x-windlimit5kts,maximumgust5kts)accordingtothe

Pilot’sCapabilityCategory(fordetails,refertoDAppendix).

At13:07:18CDT,beforetheflapsweresetto100%thevisualdescentanglewas7.7degreeswithan

increasingtrend(notethatthePAPIforrunway35wascalibratedfor3.0degrees).Whenthepilotof

N4252Greadbackthelandingclearanceforrunway35andadvised“tryingtogetdownagain”,the

flaps were simultaneously extended from 50% to 100%, whilst the speedwas at 94.8 KIAS. From

13:07:32until13:07:42CDTthespeedwasdecreasingbelow78KIAS(downtoaminimumof72KIAS

at 13:07:38 CDT), which is the recommended approach speed (for procedural details refer to E

Appendix)forthe100%flapsconfiguration.

13TheauthorofthisthesisrecalculatedthewindcomponentsconsideringFigure6-4Windcomponentdiagramasfollows:090°/13ktssteady(withgustsupto18kts)equals1kt(nogusts)tailwindand13kts(gustsupto18kts)crosswindforrunway35(356°runwaytrack).

TUGrazIMasterthesis


39


Figure2-12Go-aroundfollowingsecondapproachtorunway35andlossofcontact


0,00

5,00

10,00

15,00

20,00

25,00

13:07:55 13:08:07 13:08:19 13:08:31 13:08:43 13:08:55 13:09:07

Ry4-Path Ry35-Path

TUGrazIMasterthesis


40


-75

-60

-45

-30

-15

0

1513:08:00

13:08:03

13:08:05

13:08:09

13:08:12

13:08:14

13:08:16

13:08:19

13:08:21

13:08:24

13:08:26

13:08:29

13:08:31

13:08:35

13:08:37

13:08:40

13:08:42

13:08:45

13:08:47

13:08:50

13:08:52

13:08:55

13:08:57

13:09:00

13:09:02

Pitch Roll

0

20

40

60

80

100

13:08:00

13:08:03

13:08:05

13:08:09

13:08:12

13:08:14

13:08:16

13:08:19

13:08:21

13:08:24

13:08:26

13:08:29

13:08:31

13:08:35

13:08:37

13:08:40

13:08:42

13:08:45

13:08:47

13:08:50

13:08:52

13:08:55

13:08:57

13:09:00

13:09:02

Power

0

1

2

13:08:00

13:08:03

13:08:05

13:08:09

13:08:12

13:08:14

13:08:16

13:08:19

13:08:21

13:08:24

13:08:26

13:08:29

13:08:31

13:08:35

13:08:37

13:08:40

13:08:42

13:08:45

13:08:47

13:08:50

13:08:52

13:08:55

13:08:57

13:09:00

13:09:02

Flaps

0

500

1000

1500

13:08:00

13:08:03

13:08:05

13:08:09

13:08:12

13:08:14

13:08:16

13:08:19

13:08:21

13:08:24

13:08:26

13:08:29

13:08:31

13:08:35

13:08:37

13:08:40

13:08:42

13:08:45

13:08:47

13:08:50

13:08:52

13:08:55

13:08:57

13:09:00

13:09:02

AltB HOUelevauon

40,0

60,0

80,0

100,0

120,0

13:08:00

13:08:03

13:08:05

13:08:09

13:08:12

13:08:14

13:08:16

13:08:19

13:08:21

13:08:24

13:08:26

13:08:29

13:08:31

13:08:35

13:08:37

13:08:40

13:08:42

13:08:45

13:08:47

13:08:50

13:08:52

13:08:55

13:08:57

13:09:00

13:09:02

IAS Vs Vfe/Vno

TUGrazIMasterthesis


41



(13:07:55-13:09:07CDT)and2-24(13:08:00-13:09:02CDT)whilstperformingthesecondapproach

torunway35ofN4252Gwereanalysedindetail.

Thepilotcontinuedthefinalapproachtorunway35.At13:08:19CDTatapositioninthelastthirdof

runway35(refertoFigure2-12)atanaltitudeof107ft(64ftaboveground)andataspeedof66.7

KIAS(notethattherecommendedapproachspeedwithflaps100%is78KIAS;forproceduraldetails,

refertoEAppendix)thego-aroundwasinitiated.Thepowerwassetto96%.Theairspeedatthetime

ofgo-aroundwas66.4KIAS.Theflapswerenotretractedandleftat100%.

At13:08:45CDT,thealtitudewasat374ftwhilstperformingaslightleftbankedturn.Thestallspeed

marginreached5ktsand itcanbeassumedthatthestallwarningwastriggered14.Thepitchangle

wasnotreduced.At13:08:53CDT,withastallspeedmarginof2ktsthepowerwasreducedto78%.

At13:08:55CDT,atanaltitudeof463ftwith62.4KIASandastallspeedmarginof1kttheflapswere

retractedto50%.Althoughtheindicatedairspeedwasalreadybelowthecalculatedstallspeedand

thepitchanglewasnotreduced,thepilotcontinuedtofly inaslight leftturnwithabankangleof

approximately 20 degrees. The turn increased the tailwind component and further lowered the

energystateoftheaircraft.

At13:09:02CDT,withapitchangleof9degrees,ina26degreesbankedleftturn,thepowersetto

84%,at58.4KIAS(14.6ktsbelowthecalculatedstallspeed),atanaltitudeof496fttheflapswere

retractedto0%.Subsequently,thecontroloftheaircraftwaslost.

Thelastdatareadoutbeforetheimpactat13:09:03CDTindicatedaleftbankangleof71degrees.


TUGrazIMasterthesis


42

2.3 GeneralDefinitionsforthePresentCASTAnalysis

ReferringtoLeveson(2018),distinguishingbetweenhazardsandlossesisrequired,giventhatlosses

may involve aspects of the environment overwhich the system controllers or operators have only

partialcontrolornocontrolatall(rf.(Leveson,STPAHandbook,2018,p.17)).

FortheprevailingSTAMP(Leveson,2011)modelingoftheN4252Gaccidenttheauthorofthisthesis

has specified in the following the Loss [L], the involvedHazards [H] and the associatedHigh-Level

SafetyConstraints[HLSC]:

[L] Thelossoflifeorinjurytopeopleasaresultofapilot’slossofaircraftcontrolinflightwhilst

intendingtolandatechnologically-advancedaircraft(TAA)inabusyairportenvironment.

Thefollowinghazards[H]describesystemstatesorconditionsthatleadtotheabove-definedlossof

aircraftcontrolinaworst-casescenario:

[H-1] Aircraftapprovedenvelopeofflightisexceeded.

[H-2] “Aircraftairframeintegrityislost”(Leveson,STPAHandbook,2018,p.20).

[H-3] Regaininglostaircraftcontrolinflightisnotachievedbeforeasafegroundcontact.

[H-4] Aircraftisuncontrolled.

[H-5] CAPSisnotdeployedinalife-threateningemergency.

[H-6] Biennialflightreviewisexceeded.

[H-7] Pilot’sworkloadexceedssafelymanageablecapabilitiesanddegradesSA.

[H-8] ATCClearancesarecomplexandchangedunpredictablywithinashorttimeframe.

[H-9] Thefinalapproachiscontinuedwithoutmeetingstabilizedapproachcriteria.

ReferringtoNancyLeveson’sdefinitionofhazardinAAppendix,itseemsobviousthatenvironmental

conditionscanaffectacontroller’sprocessmodel, inso far that inaworst-casescenarioallof the

unsafecontrolactionsinitiatedbytheindividualcomponentsinteracttogethersuchthattheresultis

a loss (accident). Therefore, respective safety constraints need to be put in place tomitigate the

encounterofunsafecontrolactionsandtheinteractionsofthecomponentsasawhole.

TUGrazIMasterthesis


43

The high-level safety constraints [HLSC] and requirements associated with each of the afore-

mentionedhazardsaredefinedasfollows:

[HLSC-1] If an aircraft exceeds the approved envelope of flight, then the exceedance must be

detectedandmeasurestakentoavoidapilot’slossofaircraftcontrol(rf.(Leveson,STPA

Handbook,2018,p.20)).

[HLSC-2] “Aircraftairframeintegritymustbemaintainedunderworst-caseconditions”(Leveson,

STPAHandbook,2018,p.20).

[HLSC-3] If regaining lost aircraft control in flight cannot be expected before a safe ground

contact, then measures shall be taken on time to minimize loss-of-life or injury to

people.

[HLSC-4] Aircraftcontrolmustbemaintainedunderallconditions.

[HLSC-5] IfCAPSisnotdeployedinalife-threateningemergency,thenalternativemeasuresmust

beperformed.

[HLSC-6] If thebiennial flight review is exceeded, thenmeasuresmustbeenforced toprohibit

exercisingprivilegesaspilotincommand.

[HLSC-7] If the pilot’s workload exceeds its safely manageable capabilities, then measures to

regainasafelevelofworkloadmustbeperformed.

[HLSC-8] IftrafficsituationsrequirerevisedATCstrategiesonshortnotice,thenmeasuresmust

beenforcedtoenableaclearunderstandingforallinvolvedparties.

[HLSC-9] Ifthestabilizedapproachcriteriaarenotmetanimmediategoaroundshallbeinitiated.

TUGrazIMasterthesis


44

2.4 GeneralModelofHierarchicalControlStructure

FormodelingtheaccidentofN4252G’soperationpriortoitsfinalgroundimpactinSTAMP(Leveson,

2011), a hierarchical control structure was developed by the author, refer to Figure 2-13. It

supported the determination and understanding of the process how higher levels in the control

structure contributed to unsafe control actions by considering available information, feedbacks,

physicalflowsandenvironmentalconditions(rf.(Leveson,EngineeringaSaferWorld,2011,p.351)).

Thefollowingcodingsareapplied:

• rectanglesrepresentindividualcontrollers;

• continuouslinesrepresentcontrolactions;

• dashedlinesindicateinformation,feedbacks,orphysicalflows;

• oversizedarrowsymbolsindicatechangingenvironmentalconditions.

Figure2-13Generalmodelofhierarchicalcontrolstructure

TUGrazIMasterthesis


45

2.5 ProcessModelforeachSystemComponent

Thepotentialforinadequatecontrolforeachsystemcomponent–whichcouldultimatelyleadtothe

hazardsdefinedinChapter2.3–wasanalysedbytheauthor.Forasummarizeddescriptionforeach

systemcomponent,refertoKAppendix.

According toSTAMP (Leveson,2011), accidentsaredescribed in suchaway thateachhigher level

controlstheactivityatthe levelbelowbymeansofcontrolhierarchiesandadaptationoffeedback

mechanisms.Thisadaptationisespeciallyimportanttoavoidfutureaccidents.Theunderstandingof

theprocessandhowhigherlevelsinthecontrolstructurecontributedtounsafecontrolactionswas

emphasized.Therefore,thesafetycontrolstructureofindividualsystemcomponents(Figure2-14to

Figure2-22)wassimplifiedtotherelevantinteractionsandthefollowingsafety-relevantfactswere

modeled.Finally,theresultswerecategorizedaccordingly:

• Unsafecontrolactions(UCA)

• DysfunctionalInteractions

• Contextualfactors

• Identified Safety requirements and constraints (SC)with the link to associated hazards, as

definedinChapter2.3

• Questionsraised(QR)

TUGrazIMasterthesis


46

2.5.1 HigherControlLevel(HCL)-ControlStructure

TheauthorhasdefinedtheHCLasasummarizedtermforthehighestleveloftheHCS.Itdescribesall

higher-level control structures (such components as legislature, government regulatory agencies,

aviationauthorities,pilot’sassociationsandunions).

Figure2-14HCL-simplifiedcontrolstructure

HCL-CASTanalysisUnsafecontrol

actionsDysfunctionalinteractions Contextualfactors Safetyconstraints Questionsraised

Thelegislaturehasthepowertoenforcenewstandards/regulations.Accidentinvestigationprocessesarehardlyinvestigatedconsideringsystem-theoreticprinciples.Aviationauthorities,pilot’sassociationsandunionsmaydisseminatelessonslearnedandprovideexperience/knowledgeinrespectofflightsafety.

[SC-1_HCL]ThecompetentcomponentsoftheHCLshallemphasizetodisseminatelessonslearnedandenforceflightsafetyrecommendations(consideringsystem-theoreticprinciples)intostandards/legallaw[H-1,H-2,H-3,H-4,H-5].

TUGrazIMasterthesis


47



USflighttrainingregulationsforprivatepilotsarerathermaneuver-basedthancoveringreal-worldchallenges,whereasindustrystandardslikeFITSprovidescenariobasedtraining(includingSRM,decisionmaking,riskmanagement,etc.).

[SC-2_HCL]Considerationofindustrystandardsandtechnologicalpossibilitiesshallbepartofthelegalenforcementbasisforgeneralaviationpilots’training[H-1,H-2,H-3,H-4,H-5].

Theinvestigationreportincorporatesnodetailsofknownincidentsofthepilottotheauthority.

[QR-1]Arethereanyincidentsknowntotheauthorityinrespectoftheaccidentpilot?

SRMcoursesarenotobligatory,whichmayresultinalackofSRMknowledge.

[SC-3_HCL]SRMCoursesshallberequiredforsinglepilotsonaregularbase[H-1,H-4].

Pilot’slicenceendorsementshavenoexpirydates,whichmayresultinpilotsexercisingtheirprivilegeswithoutfulfillingtheproficiencyrequirements.

[SC-4_HCL]Expirydatesofpilot’slicenseendorsementsshallbeimplemented[H-1,H-4,H-6].

HCLarenotreceivinginformation/feedbackofUSpilotsexceedingbiennialflightreviews.

[SC-5_HCL]Flightreviewdatashallbetrackedbythecompetentauthority[H-6].

RegularcheckridesforVFRsingle-enginepistonpilotsarenotrequiredbyregulation.

[SC-6_HCL]HCLshallemphasizetoenforceregularcheckridesforVFRsingle-enginepistonpilots[H-1,H-4].

Loss-of-controltrainingisnotobligatoryforsingle-enginepilots.

[SC-7_HCL]Loss-of-controltrainingforsingle-enginepilotsshallberequired[H-3,H-4].

Aircraftparachutesystemtrainingisnotobligatoryforflightcrews,asactualtrainingrequirementsarenotcoveringallmodernsystemstandards.

[SC-8_JCL]HCLshallemphasizetoenforcetrainingrequirementsbasedonmodernindustrystandards(e.g.APStraining)[H-5].

Stressmanagementeducation,especiallyforprivatepilots,isnotenforcedbytheHCL.

[SC-9_HCL]Stressmanagementeducationforpilotsingeneralshallberequiredonaregularbase[H-7].

ATSAPisareportingprogram,butonavoluntarybaseonly.Knownsafetyissuesmightnotberesolved,ifnotreported.

[SC-10_HCL]ReportingprogramsshallbeobligatoryforATCcenters[H-7,H-8].

Auditproceduresraisingnon-compliances(findings)inrespectofcommunicationdeficienciesamongATCCenters(requiringinstantaneouslycorrectiveactions)arenotexistent.

[SC-11_HCL]RegularauditsatATCcentersshallbeaccomplishedaspartoftheoversightthroughHCL.Non-compliancesshallbeanalysedforitsrootcausesandrespectivecorrectiveactionsapplied[H-8].

TUGrazIMasterthesis


48



HCLprovidenopro-activeoversightmeasurestoprohibitflightcrewsperformingtheirdutyundertheinfluenceofmedicationswithoutAMEapproval.

[SC-12_HCL]MeasuresmustbeenforcedtoprohibitpilotsperformingtheirdutiesundertheinfluenceofprescriptionmedicationswithoutAMEapproval[H-1,H-7].

PrimaryaccidentcausalfactorsthatcontinuetoplaguethegeneralaviationcommunityhadnotbeenexplicitlydisseminatedbyHCLaslessonslearned.

[SC-13_HCL]Primaryaccidentcausalfactorsthatcontinuetoplaguethegeneralaviationcommunityshallbeexplicitlydisseminatedtothepilots[H-1,H-3,H-4].

Table2-2HCL-CASTanalysis

TUGrazIMasterthesis


49

2.5.2 TrainingOrganisation15-ControlStructure

Figure2-15Trainingorganisation-simplifiedcontrolstructure

TrainingOrganisation-CASTanalysisUnsafecontrol


Theprevailingdocumentsprovidednoinformationabouttheinitialtrainingoftheaccidentpilotandherprogress.

USpilottrainingisprovidedeitherthroughFAA-certificatedpilotschools(rf.Title14CFRpart141)orthroughothertrainingproviders(rf.Title14CFRpart61).Sometrainingorganisationsprovidescenariobasedtrainingaccordingindustrystandards(e.g.FITS).

[QR-2]Statedetailsabouttheinitialtrainingoftheaccidentpilotandherprogress(type/duration,typesofaircraft,detailsaboutdescentplanning,energymanagement,busyairportoperations,stabilizedapproachcriteria,stall/spinavoidance,CAPS)?

TheCFI-1statedthatduringthefirstflightsoftheaccidentpilot’sinstrumenttrainingeverysituationwashandledcomparabletoanystudenttheCFI-1hadworkedwith.TheCFI-1flewthreeflightswiththeaccidentpilot(September,2015).

[QR-3]Whatwasthestatus/progressoftheaccidentpilot’sinstrumenttraining?

15Author’s note: Given that the accident report does not describe any details, “training organisation” wasdefined as generic term substituting all organisations and flight instructors where the accident pilot hadreceivedflighttraining.

TUGrazIMasterthesis


50

TrainingOrganisation-CASTanalysisUnsafecontrol


TheCFI-2flewwiththeaccidentpilottwice.Bothflightswererecurrenttrainingflights.Hestatedthatthepilothandleditwithinacceptablelevelsandretainedcomposureandtheabilitytoflytheairplane.

[QR-4]WhathadbeentheweaknessesoftheaccidentpilotintheopinionoftheCFIs?

“Spinentrycanbeavoidedbyusinggoodairmanship:coordinateduseofcontrolsinturns,properairspeedcontrol,noacceleratedflightcontrolinputswhenclosetothestall”(POH-SR20,2015,p.3-28).

[QR-5]Wasgoodairmanshipinrespectofspinavoidance(asmentionedinthePOH)trained?

Theweatherconditionsatdestinationwereconsideredassuitableforlandingbythepilot.Itisnotassuredifthepilothadadequateknowledge,thatthewindlimitwasexceedingthepersonallimitsaccordingtotheCirrusFOM(EnvelopeofSafety).

[SC-14_TrgOrg]Trainingorganisationsmustassurethatpilotsareproficientinallrelevantaircraftmanualcontents(POH,FOM)oftheaircraftoperated[H-7].

[QR-6]WastheFOMwiththe“EnvelopeofSafety”taughtaspartoftheinitialtrainingfortheCirrusaircraft?

Riskawarenesswasacausalfactoroftheaccident.

[SC-15_TrgOrg]Riskawarenesstoolsshallbetrainedtopilotsconsideringactualinfluencingfactorsforinstructionflights.

Lackofpilot’sstress-andworkload-managementinfluencedtheoutcomeoftheaccident.

[QR-7]DidthepilotattendanycoursesinSRMorrelatedtopicsandwhathadbeenthecontent?

Lackofpilot’spro-activesafetycultureinfluencedthesafetyofflight.

[SC-16_TrgOrg]Procedurestokeeppro-active,personalSafetyCulturesineverypilot’smindshallbeenforced[H-6].

[QR-8]Howwasthepilot’sattitudeinrespectofherownsafetyculture?

TheCAPSwasnotactivatedwhentheaircraftenteredaspin.Itisnotassuredifthepilothadadequateknowledgeforproceduralbehaviourincaseofaircraftupsetand/orspin.

[SC-17_TrgOrg]Practicaltraininginacrobaticaircraft/simulatorstomaintainproficiencyinspinrecoveryproceduresshallbeenforced[H-5].

[QR-9]Wastheaccidentpilottrainedtorecognizelossofcontrolsituationsandhowtoescape?

Table2-3Trainingorganisation-CASTanalysis

TUGrazIMasterthesis


51

2.5.3 ATC-ControlStructure

Figure2-16ATC-simplifiedcontrolstructure

ATC-CASTanalysisUnsafecontrol


TheFLMstatedthatcommunicationthroughoutthefacilityinHOUhadrequiredimprovement.

[QR-10]WhichcommunicationprocessesattheHOUATCFacilityrequireimprovements?

Reducednumberofcontrollers,asoneofthecontrollersassignedtotheshifthadbeenmedicallydisqualifiedandanothercontrollerhadalreadybeenapprovedforhisannualleave.TheactivitylevelplacedthefacilityrightinthemiddleoftheATC8levels.

[SC-18_ATC]ItmustbeassuredthataminimumnumberofATCcontrollersisavailabletoavoidanydegradationinaviationsafety[H-7,H-8].

TheLCTwasnotsurewhytheOJTIhadtakenoverthefrequencyinsteadofjusthavinghimissuetheclearance.

ThefrequencywashandedoverafewtimesbetweentheLCTandtheOJTI(LCI).

[SC-19_ATC]OperationswithATCtraineesbeingsupervisedbyATCinstructorsmustfollowclearandconsistentprocedures[H-7,H-8].

[QR-11]WaspeerpressureinfluencingthecommunicationbetweentheATCtraineeandhisinstructor?

TUGrazIMasterthesis


52



ATCSimulatortrainingwasnotprovidedfortheLCposition,radartrainingwasprovidedviaonlinelearningtools.

[SC-20_ATC]ATCtrainingshallincludeactiveATCsimulatorsessionsratherthanonlinelearningtools[H-7,H-8].

[UCA-1]ATCrevisedtherunwayassignmentsforlandingafewtimeswithinashorttimeinterval,whichresultedinanincreasedpilot’sworkload.

[SC-21_ATC]ATCshallnotchangerunwayassignmentsforlandingwithinashorttimeintervaltoavoidunnecessarilyincreasingtheworkloadforthepilot.[H-7,H-8].

[UCA-2]ATChadnoreportsofwindshearorotherwindissuesuntiltheafternoon,whichresultedinassignmentofrunway4/35insteadofrunway12forarrivals(whichwasmoreconvenientduetothewindconditions).[UCA-3]ATCdidnotadapttherunwayassignmentsforthelowestachievablerisks,whichresultedinanavoidablecrosswindcomponentfortheactiverunway35.

“Thetowerwasnotprimarilyusingrunway12forarrivalsbecausethewindhadn’tpickedupuntiltheafternoonarrivalpushwasinprogress,andthatwasnotagoodtimetochangerunways”(rf.(NTSB,AirTrafficControl,GroupChairman'sFactualReport,CEN16FA211,2016,p.25)).

[SC-22_ATC]Runwayassignmentsshallbeadaptedforthelowestachievableriskinchangingwindconditions[H-7].

Theaircraftwasseparatedveryclosetootherapproachingaircraft.

[QR-12]Whichalternativeprocedures(exceptvisualseparation)forre-aligningaircraftinthetrafficpatternwerecommon?

[UCA-4]TheCirruswasvectoredtorunway35withtheexistingcrosswind(gustsupto20kts),althoughdifficultiesforthepilotinhandlingtheaircraftwereobvious.

TheFLMsaidthatthetowerhadbeenusingrunway35alldayforavarietyofaircraftwithnoissues.

[SC-23_ATC]RunwayassignmentproceduresforATCshallbeenforcedtoreducecrosswindcomponentsforaircraftapproachingwithobviousdifficultiesinaircrafthandling[H-7].

TheLCTstatedthattheaircraftappearedtobedefinitelytoohightolandafterbothapproachescarriedouttorunway35.

[SC-24_ATC]ATCtowercontrollersshallbetrainedtoprovideappropriateclearancesiftheaircraftisinaposition(“unstableapproach”)fromwhichasuccessfullandingcannotbeassured[H-9].

[UCA-5]Non-adherencetoICAOstandardphraseologycausedmisunderstandingsbetweenpilotandATC.

AnATCclearancetoturnrightwithoutaheadingassignmentisnotaccordingstandardICAOphraseology.

Applicationofnon-standardICAOphraseology(“keepittight”,“leftheading30degrees”)TheLCCwasaskedaboutthe“lowandtight”instruction,heansweredhehadgiveninstructionslikethattootherpilotsaswell.

[SC-25_ATC]AdherencetoICAOstandardphraseologyshallberegularlyevaluatedandexamined.Importanceofclearcommunicationshallbehighlighted[H-7,H-8].

[QR-13]AretheATCcontrollerstrainedtofollowICAOstandardphraseologyandtoavoidunnecessarilylongATCclearances,especiallyduringcriticalphasesofflight?

TUGrazIMasterthesis


53



ATCclearanceto1600ftMSLforkeepinganaircraftinthetrafficpatternrequiresclarificaton.

[QR-14]DotheLCcontrollershaveadequatetrainingforvectoringaircraftinthenearproximityoftheairportunderhigh-trafficconditions?

[UCA-6]KeepingtheaircraftinthetrafficpatterninsteadofhandingitovertotheApproachControllerincreasedthepilot’sworkload.

Non-adherencetotheletterofagreementwasaverystandardalternateplan.

FacilityBriefingandaletterofagreementstatedtotransfergo-aroundaircraftbacktotheapproachcontrolforresequencing.FortheLCIkeepingtheaircraftinthepatternwasthe“normal”response.TheLCCstatedthatifageneralaviationaircraftwentaroundhewouldprobablyhavekepttheaircraftratherthangivingitbacktoapproach.TheFLMstatedthatabout90%ofthetimeifasmallVFRaircrafthadtobere-sequencedoffrunway4,thetowerwouldhavekepttheaircraftandnothandeditofftoapproach.FortheI90controlleritwasusual,thatVFRtrafficwasworkedbackforlandingbyHOUtower.iftheyhadnotbeenabletodothat,thenI90wouldhavetakenthego-aroundaircraftbacktore-sequenceitforanotherapproach.

[SC-26_ATC]ClearATCProceduresshallbeenforcedandadheredtoassurethatsafetyhasfirstpriority.HandingoverofVFRaircrafttoapproachcontrolmustnotbecategorizedasabnormal[H-7,H-8].

Whenthepilotadvisedaboutheruncertaintyofbeingcorrectlylinedup,theATCjustcancelledthestraight-inapproachinsteadofsupportingtoregainthesituationalawareness.

[SC-27_ATC]ATCcontrollersshallbetrainedtorecognizeandsupportpilotsinregaininglostordegradedsituationalawareness[H-7].

[QR-15]WasLCcontroleverindoubt,thatN4252Gmightnotbeabletolandtheaircraftsuccessfully?

AccordingtheLCTController,thepilotneversoundedflusteredordisoriented.AccordingtotheI90Controller,thepilotofN4252Gsoundedconfident.

[QR-16]HowdoesanATCcontrollerevaluatetheconfidenceofpilots?

TUGrazIMasterthesis


54



Theapproachcontrollerwasrequiredtocontinuetomonitorthespacingonfinalevenafteraircraftwereswitchedtothetower.TheFLMcalledapproachandaskedthemtoslowtheirnextarrivaldownformorespacefortheCirrus.ThiswasnotcoordinatedwithLC.TheI90controllerdidn’tthinkHOUtowercouldsequenceN4252Ginsideofthetraffic.

Approachcontrol(I90)toldtheFLMthathewouldtakeN4252Gback,buttheFLMsawthatN4252Gwasalreadyturningbase,sohetoldapproachthatthetowerwouldjustworktheaircraft.ThiswasnotcoordinatedwithLC.TheFLMdidnotgiveanyinstructiontoLCastheyseemedtohavethesituationundercontrol.

[SC-28_ATC]TheinternalcommunicationprocessamongATCstationsshallnotbeimpaired[H-7,H-8].

[UCA-7]ATCtransmittedunnecessarilylongtothepilotgoing-around,whichresultedindistractionduringacriticalphaseofflight.

[SC-29_ATC]ATCtransmissionstoanaircraftinacriticalphaseofflightshallbekepttoaminimum[H-7,H-8].

[QR-17]DidtheLCCanticipatethehighworkloadandstressthatthepilotofN4252Gwasunderatthethirdgo-around?

[UCA-8]TheLCIwasrelievedbytheLCCinabusyandcriticalmoment(thirdgo-aroundofN4252G)afteronly2-minutesofoverlap(whichistheminimumrequiredperiod).Itcausedinsufficientsituationalawarenessforthecontrollertakingover.

LCIsshiftwasending.TheFLMhadarrangedtorelievetheLCI.TheLCCmovedtothemonitorpositionfortherequired2-minutepositionoverlapperiod.

[SC-30_ATC]OverlapperiodsofATCcontrollersshallbeadaptedtotheactualscenarioandnotbebasedsolelyonoverlap-time[H-7,H-8].

[QR-18]Howwasassured,thattheLCCtakingoverhadsufficientsituationalawarenessabouttheATCtrafficsituation?

TheFLMhadtriedtogetcrewbriefingstogethersincehegottoHOU,butstaffinghadbeenshortandbriefingshadbeenhardtoaccommodate.Somecontrollershadneverseencertainsituations.Valueoftheseexperienceswerenottaughtwellenough.

FortheLCI,havinganaircraftmisstherunwaytwicewasthefirsttimehehadseenthat.TheLCIhasnotparticipatedinanycrewbriefingsincehecametoHOU.Accordingtohim,therewasnopracticeofdiscussingincidentsandaccidentsaslearningexperiences.TheLCCstatedthathehadnotattendedmanycrewbriefingsinthepastfewyears,andthattheywerenotregularevents.

[SC-31_ATC]RegulartrainingeventstoshareeachATCcontroller’sexperiencesshallbeaccommodated[H-8,H-9].

[QR-19]HowisitassuredthatindividualproceduresandworkingpracticesaresharedamongeveryATCteammember?

TheFLMhadnotcompletedmanyPRCstodocumentcontrollerperformance(headmitteditasanerroronhispart).PoordocumentationofperformancemanagementbytheFLM.

[QR20]HowwastheperformanceofATCcontrollersassured?

TUGrazIMasterthesis


55



ATSAPreportswerenotappliedinHOU.

[SC-32_ATC]Non-punitivereportingculturesforATCcontrollersshallbeobligatoryforeachATCcenterforahigherlevelofexperienceexchange[H-1,H-7,H-8,H-9].

Table2-4ATC-CASTanalysis

TUGrazIMasterthesis


56

2.5.4 AircraftManufacturer(Cirrus)-ControlStructure

Figure2-17Aircraftmanufacturer-simplifiedcontrolstructure

AircraftManufacturer-CASTanalysisUnsafecontrol


ThePOHinVersionA1hasbeenvalidandunrevisedsinceDecember29,2015.

[QR-21]WhatschedulestheissueofnewPOHrevisions?

[UCA-9]“TheonlyapprovedanddemonstratedmethodofspinrecoveryisactivationoftheCAPS”(POH-SR20,2015,p.3-28).Possiblealternativeproceduresforspinprevention/recoveryarenotprovidedinPOH,resultinginlimitedmentalprocessmodelsforthepilotincaseCAPSisnotactivated/available.

[QR-22]WhatisthealternativeprocedureforpilotsiftheCAPSsystemcannotbeactivatedincaseofanunintendedspin?

TUGrazIMasterthesis


57

AircraftManufacturer-CASTanalysisUnsafecontrol


ThePOH-SR20(2015)states,thattheSR20istrimmedbyadjustingtheneutralpositionofthecompressionspringcartridge(rf.(POH-SR20,2015,p.7-8,7-10)),whichprovidesanartificial“forceagainstaspringcartridge”onthecontrolyoke.Theassociatedrisksofspring-cartridgesarenotdescribedinthePOH.

[SC-33_Cirrus]UnusualartificialfeelingsonacontrolyokeanditsassociatedrisksshallbedescribedinthePOH[H-1,H-2].

[QR-23]Wasthepilotawareoftheassociatedrisksdueartificialaerodynamicforcesonthecontrolyoke?

TheflapswereextendedaboveVfe.

[SC-34_Cirrus]Improperpilot’sactionsexceedingaircraftlimitationsorendangeringthesafetyofflightshallbeavoided[H-1].

. LimitedAircraftFeedbackfornextflapsetting(speedscaleonairspeedindicator).

Theflapswereretractedbelowtherecommendedflapretractionspeedcausingtheaircrafttostall.

[SC-35_Cirrus]ThePOHshallclearlystateawarningthatretractingflapsbelowtherecommendedstallspeedsisofutmostdangeroflosingcontroloftheaircraft[H-1,H-4].

N4252Gwaslostduetotheinabilitytoregainaircraftcontrol.

“LossofControlisoneofthesixmostcriticalandcommoncausesofGA[generalaviation]accidents”(USDepartmentofTransportation,AC61-98D(supersedesAC61-98C),2018,p.2-1).

[QR-24]HowdoesthemanufacturerassurethatLOCisavoidedinCirrusaircraft?

Table2-5Aircraftmanufacturer-CASTanalysis

TUGrazIMasterthesis


58

2.5.5 COPA-ControlStructure

Figure2-18COPA-simplifiedcontrolstructure

COPA-CASTanalysisUnsafecontrol


“TheCPPPisdesignedtoexposeCirruspilotstosituationstheymayencounterwhileoperatingtheiraircraft”(FOM-SR20,2011,p.2-4).

[QR-25]DidtheaccidentpilotparticipateinanyCPPPtraining?

“TheCDMseminarisafacilitatedinteractivehangar-flyingsessionwherethegrouplooksatgeneralaviationandCirrusaccidentstatistics,reviewscasestudiesofCirrusaccidents,andparticipatesinthereenactmentofanactualaccident”(FOM-SR20,2011,p.2-4).

[QR-26]DidtheaccidentpilotparticipateinanyCDMseminar?

“ThePartnerinCommandseminarhasbeendesignedtogivefrequentCirruspassengersmoreknowledgeregardingsafetysystemoperations”(FOM-SR20,2011,p.2-4).

" [QR-27]DidanyofthepassengersparticipateinaPartnerinCommandseminar?

Table2-6COPA-CASTanalysis

TUGrazIMasterthesis


59

2.5.6 HOUAirport-ControlStructure

Figure2-19HOUairport-simplifiedcontrolstructure

HOUAirport-CASTanalysisUnsafecontrol


ThecontentsoftheactualNOTAMsandweatherforecastsonthedayofaccidentisnotmentionedintheaccidentinvestigationreport.

[QR-28]DidtheactualNOTAMsatthedayoftheaccidentstateanydeficienciesinfluencingthesafetyofflight(e.g.unserviceabilityofPAPI,displacedthresholds,etc.)?

TheATCcontrollerswerenotinformedoftheexactlocationofthewindsensor,thereforeanexactwindassignmentwasnotachievable.

TheFLMstatedthathewasnotsurewherethewindsensorwaslocatedontheairport,butnotedthattherewassoontobeachangeinthesystem.

[SC-36_HOU]ATCcontrollersshallbeinformedwherethewindsensorsarelocatedtoassigntheactualwindproperly.

Table2-7HOUairport-CASTanalysis

TUGrazIMasterthesis


60

2.5.7 Operator/AircraftOwner-ControlStructure

Figure2-20Operator/Aircraftowner-simplifiedcontrolstructure

Operator/AircraftOwner-CASTanalysisUnsafecontrol


NeithertheofficialaccidentreportnorrecherchesbytheauthorofthisthesisprovideddetailsaboutrequirementsoftheownertopermitapilottooperateN4252G.

[QR-29]Underwhichpre-requisitesdidtheoperator/aircraftownerpermitthepilottooperatetheaircraft?

[UCA-10]Theoperatorpermittedtooperatehisaircraftbyapilotwithoutavalidbiennialflightreview,whichcausedthepotential,thatthepilot’slackofproficiency,skillsandaeronauticalknowledgehadbeenundetected.

[QR-30]Whatwastheoperator’s/aircraftowner’ssafetypolicy(requirements,currency,training)forpilotsoperatingtheaircraft?

Table2-8Operator/Aircraftowner-CASTanalysis

TUGrazIMasterthesis


61

2.5.8 Pilot-ControlStructure

Figure2-21Pilot-simplifiedcontrolstructure

Pilot-CASTanalysisUnsafecontrol


Pilot’sgeneralexperienceonthetypeandothertypesofaircraft.Note:Theprevailingdocumentationdoesneitherstatedetailsreferringtopilot’sflighthours/landings(flighthourswithinthelast12months,pilot’slandingsintotal/within12months/within3months)nortoexperiencesonvarioustypes.

[QR-31]Whatarethedetailsconcerningtheaccidentpilot’stypesofaircraftflown,flighthoursandlandings.

Properflightpreparation.Note:Nodocumentationsabouttheflightplanningpackagewasfound.

[QR-32]DidthepilothaveaflightplanningpackageincludingweatherforecastandNOTAMs?

TUGrazIMasterthesis


62



Riskassessmentprocedure.Note:Nodocumentationsabouttheapplicationofriskassessmenttoolsthroughthepilotwasfound.

[QR-33]Didtheaccidentpilotapplyanyriskassessmenttools?

[UCA11]Thepilotperformedactivedutiesundertheinfluenceofaprescriptionmedication(“Zolpidem”)thatmayimpairmentaland/orphysicalabilityinconductingpotentiallyhazardoustaskssuchasflying(NTSB,AviationAccidentFinalReport,2017,p.8).

[SC-37_Pilot]Performingactiveflightdutiesundertheinfluenceofprescribedmedication,whichhasnotbeenaeromedicallyprescribed,shallbestrictlyprohibited[H-1,H-3,H-4,H-5,H-7,H-9].

[QR-34]Didthepilotwaitatleast24hoursaftertakingZolpidembeforeherflyingactivity(asrecommendedbytheFAA)?

ThepilothadnotflowntoHOUairportbefore.HOUisahigh-traffic,class-B(airspace)airport.

[SC-38_Pilot]Theimportanceofproperflightplanningandpreparationshallbeemphasized[H-7].

[QR-35]Howdidthepilotpreparefortheflightandwhathadbeenthecontentsoftheflightplanningpackage?

[UCA-12]Thepilotdidnotassesstherisksforthecrosswindcondition,whichresultedinanexceedanceoftherecommendedwindlimitaccordingtotheCirrusFOM(EnvelopeofSafety).

ThePOH-SR20(2015)statesthat,operationindirectcrosswindsof20ktshasbeendemonstrated(rf.(POH-SR20,2015,p.4-21)).

[SC-39_Pilot]Riskassessmentshallbeperformedbeforeandregularlyduringaflighttobepreparedforrapidlychangingconditionsinthedynamicaviationenvironment[H-7].

[QR-36]Whatwasthepilot’sattitudeinrespectofriskassessment?

[UCA-13]ThepilotdidnotprotestaboutthepermanentlychangingcoursesofactionbyATC,whichresultedinanincreasedworkload.

LackofAssertiveness. [SC-40_Pilot]PilotsshallbetrainednottoacceptATCclearancescausingworkload,whichisexceedingthepersonalcapabilities[H-1,H-8,H-9].

Noevidencewasfoundthatthepilothadaccomplishedasatisfactoryflightreviewwithinthepreceding24calendarmonths(rf.(Title14CFR61.56(c)).

Therelativelyhighexperience(>300hourswithin2yearsofflying)ontheSR20aircraftprovidedthepilotamisleadinglevelofconfidence.Skillsofperformingsafety-relevantmaneuvers(stabilizedapproaches,go-aroundmaneuvers,slowflight,stallrecognitionandrecovery,recoveryfromunusualattitudes,spinrecognitionandavoidance)hadlacked.

[SC-41_Pilot]Safety-relevantmaneuversshallbeperformedstrictlyaccordingtoprocedures[H-1,H-9].

[QR-37]Didthepilotperformanytrainingflightsoraflightreviewbeforetheaccident?

UncertaintyabouttheATCintentionsexistedThepilotgotdisorientedandlosttheclearpicturewheretherunwayshouldbelocated.

Lossofsituationalawarenessmaybeinfluencedbychannelizedattention(tunnelvision),distractionandtasksaturation.

[SC-42_Pilot]Theimportanceofsterilecabinproceduresshallbeemphasized[H-7].[SC-43_Pilot]Methodsandproceduresforrecognizingandregaininglostsituationalawarenessshallbetaught[H-3].

[QR-38]Wasthepilot’slevelofsituationalawarenessimpairedbyanyreasonandcouldthepilotingeneralbedistractedeasilywhenperformingtasks?

TUGrazIMasterthesis


63



[UCA-14]ThepilotdidnotprioritizetostabilizetheflightpathbeforecommunicatingwithATCduringcriticalphasesofflight,whichdistractedandincreasedtheworkload.

[SC-44_Pilot]Communicationannouncementsshallbeperformedaftertheflightpathissafelystabilized(“aviate-navigate-communicate”procedure)[H-1,H-7].

[UCA-15]Pilottaskswerenotprioritizedcorrectly,whichresultedinalossofsituationalawareness.[UCA-16]Thepilotaccepted,thatATCwaskeepingtheaircraftinthepatterninsteadofrequestingalternativemeasurestolowerherworkload.

Pilot’sworkloadwasnotreduced.

Thepilotwassubjecttohighworkload(“seeandavoid”separation,waketurbulencehazard,changingcomplexATCclearanceswithinshorttime,complexmaneuvers,passengers).Thepilotlackedassertiveness.Peerpressuretolandtheaircraftattheplanneddestinationwasexistent(“thirdtimewillbeacharm”).

[SC-45_Pilot]TheimportanceofSRMtrainingcoursesshallbeemphasizedtoprovideprocedurestocopewithhighworkloadsituations[H-7].

[QR-39]WasthepilottrainedinSRM?[QR-40]Hadthepilotbeensubjecttotimepressure(appointment)onthedayoftheaccident?

[UCA-17]Theflapswereextendedto50%ataspeed>10ktsaboveVfe,whichresultedinexceedingtheapprovedandsafeflightenvelope.

ATCadvisedthepilottokeepthespeedup.Thepilotdidnotannouncetheinabilitytocomply.

[SC-46_Pilot]IfATCrequestscannotbecompliedwith,proceduresforenergyandATCmanagementshallbeenforced[H-1,H-9].

[UCA-18]Safeairspeedcontrolwasnotachieved,whichresultedinexceedingtheapprovedandsafeflightenvelope.[UCA-19]Whentheapproachspeedwasdeceedingtherecommendedspeed,thepitchanglewasnotreducedandthespeeddecreasedfurtheruntilstall.

Thepilotmighthavemistakenprocedures/airspeedswithotheraircraftflowninthepast.

[SC-47_Pilot]Proceduresforcorrectairspeedcontrolandsubsequentaircrafttrimshallbeenforced[H-1,H-7,H-9].

[QR-41]Didthepilotactivelyoperateonothertypesofaircraftintherecentpast?[QR-42]Wasthepilotapplyingcorrecttrimprocedures?[QR-43]ArethereanyRDMdataavailableinregardsofaircrafttrim?

[UCA-20]Thepilotdidnotstartthefinaldescentappropriatelyinrespectoftheaimingpoint,whichresultedinendinguptoohighforthelanding.

Visualillusion(falseadoptionofhorizonafterlongcruiseflights)affectsstabilizedapproachcriteriaandcontrolofaircraft.

[SC-48_Pilot]Procedurestocopewiththeinfluenceofvisualillusionsshallbeenforced[H-1,H-9].[SC-49_Pilot]Proceduresfortheconsiderationofvisualglideslopeindications(PAPI)shallbeenforced[H-1,H-9].

[QR-44]Wasthepilotawareofpossiblevisualillusions?

[UCA-21]Stabilizedapproachcriteriawerenotfulfilled,whichresultedinendinguptoohighforthelanding.[UCA-22]Thepilotdidnotmanagetheglideanglewithflapsand/orside-slipasnecessary(rf.(FOM-SR20,2011,p.4-11)).

Theaircraftwasnotslowedtoaspeedthatallowedthepilottoperformastabilizedapproachinatimelymanner(rf.(FOM-SR20,2011,p.3-58)).

Modern,efficientwingdesignsproducelowdragandspeeddeductionmightsuffer.Side-slipmaneuversmaybeusedtoincreaserateofdescentwithoutspeedincrease.

[SC-50_Pilot]Procedurestoperformproperenergymanagement(powercontrol,side-slipmaneuvers)tocomplywithstabilizedapproachcriteriashallbeemphasized[H-9].

[QR-45]Hadtherebeenanyincidentsbythepilotinrespectofunstabilizedapproachesatotherairports?[QR-46]Wasthepilottrained/assessedforside-slipmaneuvers?

TUGrazIMasterthesis


64



[UCA-23]Thepilotoverbankedtheaircraft,whichresultedinexceedingmaximumbankanglesduringvisualmaneuvering.[UCA-24]Thepilotencountereduncertaintyabouttheactualaircraftposition(tocomplywiththeassignedATCclearances),whichresultedinuncoordinatedandunusualaircraftattitudesinlowaltitude.

Navigatingcomplexmaneuversdistractspilotsfrombasicaviating.

High-trafficsituationinclass-Bairspaceinthecloseproximityofanairportwithcrossingrunwaysrequireshighnavigationalcapabilitiestoavoiderrors.Unusualattitudesinlowaltitudesmaybeasignofuncertainnavigationcapabilities.Deficienciesinvisionmaydistractthepilotfromreadingthenavigationchartsproperly.Electronicchartsmayfail.

[SC-51_Pilot]Pilotsshallknowtoavoidhighbankanglesinlowlevelflying[H-1,H-9].[SC-52_Pilot]Navigationalchartsmustbeeasytoreadandhaveabackup[H-7].

[QR-47]Whichchartshadbeenusedasreferencefornavigation?[QR-48]Wasthepilotabletoreadthechartsproperly?

[UCA-25]ThepilotdidnotrecognizetheinabilitytolandfromtheactualpositionuntilconcernswereraisedbyATC(“ifthat’stoohighwecanputyouback[…],don’tforceitifyoucan’t”,“youmightbetoohigh”),whichresultedinago-aroundatalatestage.

Thelateandincorrectinitiationofthego-aroundmightbeasignforuncertaintyofago-aroundprocedure.

[SC-53_Pilot]Proceduresmustbeenforcedthatpilotsoncontrolarealwaysawarewhenandhowtoinitiateago-aroundtomaintainthehighestachievablelevelofsafetymargin[H-9].

[UCA-26]Theprocedureforbalkedlandings(go-arounds)wasnotfollowedcorrectly(fullpowernotapplied,incorrectspeeds,inadequatecoordination),whichresultedinexceedingtheapprovedflightenvelope.

Thego-aroundisacomplexanddemandingprocedure,asmanyactionsneedtobeperformedinashorttimeclosetotheground.Reducedpowersettingswerecontributing.

[SC-54_Pilot]Apilotmustbeabletoperformacorrectgo-aroundprocedureinanysituation,irrespectiveofexternalinfluences[H-9].

[QR-49]Whatwasthereasonforapplyingreducedpowersettingsforthego-around?

[UCA-27]Theincreasingtailwindcomponentloweringtheenergystateoftheaircraftwasneglected.

[SC-55_Pilot]Theinfluenceofwindcomponentsinperformanceshallneverbeunderestimated[H-1].

[UCA-28]StallWarningswereneglectedbythepilot,whichresultedinfurtherspeeddecrease.[UCA-29]Theaircraftwasstalleddueuncoordinatedpitchcontrolandretractionoftheflaps.

Lostsituationalawarenesscausesevenobviouswarningsignals(stallwarning)tobeignored.

[SC-56_Pilot]Measuresshallbeenforcedtomaintainthehighestlevelofsituationalawareness[H-7].

[QR-50]Wasthepre-flightcheckincl.stallwarningsystemcheckperformedproperly?[QR-51]DidATCrecordanystallwarningsignalsonthetransmissiontapes?[QR-52]DoestheRDMstoreanactivestallwarningtrigger?

[UCA-30]Controlovertheaircraftwaslostandnotrecovereduntilthefatalgroundimpact.

Thepilot“maybedisorientedbeyondthepointwheretraditional,handflownrecoverytechniquesareeffective”(FOM-SR20,2011,p.4-40).

[SC-57_Pilot]Procedurestoavoidandescapelossofaircraftcontrolshallalwaysbethefirstpriorityofanypilot[H-3,H-4,H-5].

TUGrazIMasterthesis


65



[UCA-31]CAPShadnotbeendeployedbythepilotwhenrequired,whichresultedinanon-deceleratedaircraftimpactonground.

StartleEffectmayhaveaffectedthepilot’sabilitytocopewiththesituationontime.

referto[SC-61_Paxe] [QR-53]DidthepilotperformanyCAPStraining?

Table2-9Pilot-CASTanalysis

TUGrazIMasterthesis


66

2.5.9 Passengers-ControlStructure

Figure2-22Passengers-simplifiedcontrolstructure

Passengers-CASTanalysisUnsafecontrol


Timepressureinfluencesdecision-making.

[QR-54]Wereanyofthepassengersontheflightundertimepressure?

Convectiveweathercausesturbulences.Medicalimpairmentorairsicknessofpassengersmightcausethepilottobedistracted.

[QR-55]Wereanyofthepassengersknownforairsicknessorotherphysiologicaldeficiencies?

Thepilotmaybedistractedbythepassengers(e.g.dueconversations,airsickness,fearofflying,etc.).

[SC-58_Paxe]Passengersshallbeawareofsterilecabinproceduresandavoiddistractingthepilot[H-7].

[QR-56]Hadpassengersbeenbriefedonsterilecabinprocedures?

Passengersmaysupportthepilotinhighworkloadenvironment(airspacescan,awarenessofstabilizedapproachcriteria,etc.).

[SC-59_Paxe]PassengersshallbeconsideredasaresourceinSRM[H-7].

[QR-57]Didthepassengersfrequentlyflywithsingle-enginepistonaircraftand/orhaveextensiveaviationknowledge?

Multiplego-arounds,highdescentrates,unusualattitudes,gustycrosswindconditionsandtherecognitionofhighworkloadforthepilotmayscarepassengersandcausedistractionsforthepilot.

[SC-60_Paxe]Pilotsshallbetrainedinprocedurestoprovideasafeandcomfortableatmosphereforpassengers[H-7].

[UCA-32]NoneofthepassengershadconsideredtoactivateCAPSwhenrequired,whichresultedinannon-decleratedaircraftimpactonground.

RegardingCAPSactivation“nominimumaltitudefordeploymenthasbeenset”(POH-SR20,2015,p.10-6).

[SC-61_Paxe]AnybodyonboardshallknowaboutactivatingCAPS,iflife-threateningsituationspersist(whichrequiresdetailedpreflghtbriefingforpassengers)[H-5].

[QR-58]Hadthepassengersbeenbriefedaboutlife-threateningsituationsrequiringtheactivationofCAPS?

Table2-10Passengers-CASTanalysis

TUGrazIMasterthesis


67

2.5.10 Aircraft-ControlStructure

Figure2-23Aircraft-simplifiedcontrolstructure

Aircraft-CASTanalysis

Unsafecontrol Dysfunctionalinteractions Contextualfactors Safetyconstraints Questionsraised

[UCA-33]Thestallwarningsystemwasneglectedbythepilot,whichresultedinfurtherdecelerationandactualstalloftheaircraft.

[QR-59]Wasthestallwarningsystemfunctionableontheaccidentflight?[QR-60]Wasthepilotawareofaerodynamicaircraftreactionswhenapproachingstallconditions?

Safeairspeedcontrolwasnotachieved.

Theinabilitytoreadtheprimaryflightinformationdatafromthecockpitannunciationsmayleadtoexceedancesoftheapprovedflightenvelope.

[QR-61]WasthereanyfailureoftheprimaryflightdisplaysloggedbytheRDM?[QR-62]Didtheprimaryflightdisplayfailorgetinanunreadablecondition?[QR-63]Didtheaccidentaircrafthavealternateindicationsoftheprimaryflightinformation(speed,altitude,attitude)?

TUGrazIMasterthesis


68

Aircraft-CASTanalysis

Unsafecontrol Dysfunctionalinteractions Contextualfactors Safetyconstraints Questionsraised

Thetrimsettingoftheaircraftonimpactwasnotdocumentedintheinvestigationreport,whichwouldprovideaninformationaboutforcesonthepilot’syoke.

[QR-64]Forwhichspeedwastheaircrafttrimmedbeforethefinalimpact?

Dataoverloadthroughtheon-boardavionicsmayimpairtheabilityofpilotstoeffectivelyoperatetheaircraft.

[SC-62_Aircraft]Aircraftsystemindicationsshallbesimpletounderstandandread[H-7].

[UCA-34]Theaircraftincorporatesnoactiveattention-getterremindingofactivatingCAPSinlife-threateningsituations(spininlowaltitude),whichresultedinanon-deceleratedaircraftimpactwithoutactivatedCAPS.

Startleeffectimpairstheabilitytotakeappropriateaction.

[SC-63_Aircraft]ProceduresofactivatingCAPSinlife-threateningsituationsshallbebroughttonoticeableattentioninthecabin[H-5].

Table2-11Aircraft-CASTanalysis

TUGrazIMasterthesis

Results

69

3 RESULTS

AsLevesonnoted“oneconsequenceofthecompletenessofaSTAMPanalysisisthatmanypossible

recommendationsmayresult-insomecases,toomanytobepracticaltoincludeinthefinalaccident

report. A determination of the relative importance of the potential recommendations may be

requiredintermsofhavingthegreatestimpactonthelargestnumberofpotentialfutureaccidents.

There is no algorithm for identifying these recommendations, nor can there be. Political and

situational factors will always be involved in such decisions. Understanding the entire accident

process and the overall safety control structure should help with this identification, however“

(Leveson,EngineeringaSaferWorld,2011,p.384).

The prevailing CAST modeling of the N4252G accident was based on available information and

detailedrecherchesbytheauthor.Emphasiswasplacedonunderstandinghowhigher levels inthe

hierarchical control structure influenced/ allowed unsafe control actions. The following safety

recommendationsaspartoftheresultsoftheSTAMP-basedanalysiswerecreatedbytheauthorin

relationtothedevelopedsafetyconstraints,consideringmeasurestoprotectthemfromerosionof

safetyovertime.FordetailsrefertothefollowingTable3-1Safetyrecommendations.

Safetyconstraints Safetyrecommendations

[SC-1_HCL] ThecompetentcomponentsoftheHCLshallemphasizetodisseminatelessonslearnedandenforceflightsafetyrecommendations(consideringsystem-theoreticprinciples)intostandards/legallaw.

[REC-1] Legallawshallbeadaptedinaway,thataccidentinvestigationprocessesareinvestigatedconsideringsystem-theoreticprinciplesandprovidesafetyrecommendations,whichareimplementedinthestandards/legislation.

[SC-2_HCL] Considerationofindustrystandardsandtechnologicalpossibilitiesshallbepartofthelegalenforcementbasisforgeneralaviationpilots’training.

[REC-2] Pilottrainingshallbebasedonmodernequipmentusedandonreal-lifescenarios(includingSRM,decisionmakingandriskassessment),ratherthansolelyonmaneuvers.Trainingstandardsyllabishallberevisedonaregularbase,consideringindustrytechnicalstandardsandlessonslearnedfromrecentaccidents/incidents.

[SC-3_HCL] SRMCoursesshallberequiredforsinglepilotsonaregularbase.

[REC-3] Regulartraininginsingle-pilotresourcemanagementshallbearequirementforpilotsexercisingtheirlicenses.

[SC-4_HCL] Expirydatesofpilot’slicenseendorsementsshallbeimplemented.

[REC-4] Pilot’slicenseendorsementsshallberestrictedbyexpirydates,whichrequirepre-requisiteswhichcanbeadaptedaccordinglybythelegislation.

[SC-5_HCL] Flightreviewdatashallbetrackedbythecompetentauthority.

[REC-5] Checkairmen(examiner)shallbeprovidedwithatooltoforwardproficiencyassessmentsofperformedflightreviewstothecompetentauthority,whichenablestotracktheflightcrews’proficiencystatus.

TUGrazIMasterthesis

Results

70

Safetyconstraints Safetyrecommendations[SC-6_HCL] HCLshallemphasizetoenforceregularcheck

ridesforVFRsingle-enginepistonpilots.[REC-6] Checkridesshallberequiredtorevalidate

VFRsingle-enginepilot’slicenseendorsementsconsideringtheproficiencyofthepilot.Formoreexperiencedpilotstheintervalrequiredtorevalidatethelicensemaybeextendedondiscretionofthecheckairman(examiner).

[SC-7_HCL] Loss-of-controltrainingforsingle-enginepilotsshallberequired.

[REC-7] Loss-of-controltrainingforpilotsshallberequiredonaregularbaseandtrackedbytheauthority.

[SC-8_HCL] HCLshallemphasizetoenforcetrainingrequirementsbasedonmodernindustrystandards(e.g.APStraining).

[REC-8] Pilotsshallbetrainedinaircraftparachutesystemsonaregularbaseandtrackedbytheauthority.

[SC-9_HCL] Stressmanagementeducationforpilotsingeneralshallberequiredonaregularbase.

[REC-9] Stressmanagementeducationforpilotsincludingcoachingshallberequiredonaregularbase.

[SC-10_HCL] ReportingprogramsshallbeobligatoryforATCcenters.

[REC-10] ATCcentersshallapplyaformalsafetyreportingsystemaswellasanindependentfeedbackchannelaboutprocesssafetyconcernsbyemployees.

[SC-11_HCL] RegularauditsatATCcentersshallbeaccomplishedaspartoftheoversightthroughHCL.Non-compliancesshallbeanalysedforitsrootcausesandrespectivecorrectiveactionsapplied.

[REC-11] CompetentauthoritiesshallaccomplishregularauditsatATCcentersandraiseappropriatefindingsrequiringappropriaterootcauseanalysesandcorrectiveactionplans(aspartofthesafety-management-system).

[SC-12_HCL] MeasuresmustbeenforcedtoprohibitpilotsperformingtheirdutiesundertheinfluenceofprescriptionmedicationswithoutAMEapproval.

[REC-12] Unannounceddrugandalcoholtestprogramsofpilotsshallbeestablishedbythecompetentauthority.

[SC-13_HCL] Primaryaccidentcausalfactorsthatcontinuetoplaguethegeneralaviationcommunityshallbeexplicitlydisseminatedtothepilots.

[REC-13] Pilotsshallbepromotedtoengageinincentiveproficiencyplatforms(e.g.WINGS)toenhancetheirknowledgeofprimarycausalaccidentfactors.

[SC-14_TrOrg] Trainingorganisationsmustassurethatpilotsareproficientinallrelevantaircraftmanualcontents(POH,FOM)oftheaircraftoperated.

[REC-14] Measuresshallbeenforcedthatrelevantaircraftmanualcontentsarerefreshed/reviewedregularlybythepilots.

[SC-15_TrOrg] Riskawarenesstoolsshallbetrainedtopilotsconsideringactualinfluencingfactorsforinstructionflights.

[REC-15] Establishpromotionsabouttheimportanceofriskassessmentsatplacesfrequentlyattendedbypilots.

[SC-16_TrOrg] Procedurestokeeppro-active,personalSafetyCulturesineverypilot’smindshallbeenforced

[REC-16] Ensurethateverypilotunderstandsthatapro-active,personalSafetyCultureisofutmostimportance.

[SC-17_TrOrg] Practicaltraininginacrobaticaircraft/simulatorstomaintainproficiencyinspinrecoveryproceduresshallbeenforced.

[REC-17] Practicaltraininginacrobaticaircraft/simulatorstomaintainproficiencyinspinrecoveryproceduresshallberequiredbyregulation.

[SC-18_ATC] ItmustbeassuredthataminimumnumberofATCcontrollersisavailabletoavoidanydegradationinaviationsafety.

[REC-18] EnsurethatasufficientnumberofATCcontrollersisavailableandhavealternativemeasuresforunexpecteddeficiencies.

[SC-19_ATC] OperationswithATCtraineesbeingsupervisedbyATCinstructorsmustfollowclearandconsistentprocedures.

[REC-19] Supervisiontasksrequireclear,establishedprocedures,whichshallbebriefedtoeachotherbeforethefirstdutyoftheday.

[SC-20_ATC] ATCtrainingshallincludeactiveATCsimulatorsessionsratherthanonlinelearningtools.

[REC-20] ATCtrainingshallberegularlyperformedinATCsimulatorsformaximumbenefitofsafety.

TUGrazIMasterthesis

Results

71

Safetyconstraints Safetyrecommendations[SC-21_ATC] ATCshallnotchangerunwayassignmentsfor

landingwithinashorttimeintervaltoavoidunnecessarilyincreasingtheworkloadforthepilot.

[REC-21] ATCre-clearancesrequiringashort-timedecision-makingprocessofthepilotoveranextendedperiodoftimeshallbeavoided.

[SC-22_ATC] Runwayassignmentsshallbeadaptedforthelowestachievableriskinchangingwindconditions.

[REC-22] Runwayassignmentsshallbeadaptedforcontinuouslyachievingthehighestlevelofpossiblesafety.

[SC-23_ATC] RunwayassignmentproceduresforATCshallbeenforcedtoreducecrosswindcomponentsforaircraftapproachingwithobviousdifficultiesinaircrafthandling.

referto[REC-22]

[SC-24_ATC] ATCtowercontrollersshallbetrainedtoprovideappropriateclearancesiftheaircraftisinaposition(“unstableapproach”)fromwhichasuccessfullandingcannotbeassured.

[REC-23] ATCcontrollersshallbetrainedtorecognizeunstableapproachconditionsandprovideappropriateclearancestoregainamaximumlevelofsafety.

[SC-25_ATC] AdherencetoICAOstandardphraseologyshallberegularlyevaluatedandexamined.Importanceofclearcommunicationshallbehighlighted.

[REC-24] AdherenceofATCcontrollerstoICAOstandardphraseologyshallbemonitored(regularstandardphraseologyexams)andappropriatetrainingmeasurestakenifneeded.

[SC-26_ATC] ClearATCProceduresshallbeenforcedandadheredtoassurethatsafetyhasfirstpriority.HandingoverofVFRaircrafttoapproachcontrolmustnotbecategorizedasabnormal.

[REC-25] ATChabitsshallbemonitoredforcompliancetoapplicableprocedures.Incaseofdeviationsre-evaluationstoregainthehighestlevelofsafetyshallbeapplied.

[SC-27_ATC] ATCcontrollersshallbetrainedtorecognizeandsupportpilotsinregaininglostordegradedsituationalawareness.

[REC-26] ATCcontrollersshallbetrainedtorecognizelostordegradedlevelsofsituationalawarenessofpilotsandhowtosupportthemtoregainamaximumlevelofsafety.

[SC-28_ATC] InternalcommunicationprocessesamongATCstationsshallnotbeimpaired.

[REC-27] ForinternalcommunicationamongATCstations,itshallbeassuredthatinformationconcerningtheactualtaskisforwardedtothecontrollersincharge.

[SC-29_ATC] ATCtransmissionstoanaircraftinacriticalphaseofflightshallbekepttoaminimum.

[REC-28] ATCcontrollersshallbetrainednottodistractpilotswithunnecessarilylongtransmissionsincriticalphasesofflight.

[SC-30_ATC] OverlapperiodsofATCcontrollersshallbeadaptedtotheactualscenarioandnotbebasedsolelyonoverlap-time.

[REC-29] ATCoverlapsshallnotbefinishedaslongasasufficientlevelofsituationalawarenessoftheATCcontrollertakingoverisnotachieved.

[SC-31_ATC] RegulartrainingeventstoshareeachATCcontroller’sexperiencesshallbeaccommodated.

[REC-30] ItshallbeassuredthatregulartrainingeventsofATCcontrollersareaccommodatedtoshareindividualexperiences.

[SC-32_ATC] Non-punitivereportingculturesforATCcontrollersshallbeobligatoryforeachATCcenterforahigherlevelofexperienceexchange.

referto[REC-10]

[SC-33_Cirrus] UnusualartificialfeelingsonacontrolyokeanditsassociatedrisksshallbedescribedinthePOH.

[REC-31] Itmustbeassuredthatapilotiswarnedofaircraftsystemswithunusualcharacteristicsandassociatedrisksinapropermanner.

[SC-34_Cirrus] Improperpilot’sactionsexceedingaircraftlimitationsorendangeringthesafetyofflightshallbeavoided.

[REC-32] ReferringtoFOM-SR20(2011),pilotsshallbedisciplinedtofollowstandardproceduresduringflightoperations,astheywilldevelophabitpatternsthroughrepetitionthatallowstobemostefficientwhilecompletingtasksandconfiguringtheaircraftforvariousphasesofflight(rf.(FOM-SR20,2011,p.3-3)).

TUGrazIMasterthesis

Results

72

Safetyconstraints Safetyrecommendations[SC-35_Cirrus] ThePOHshallclearlystateawarningthat

retractingflapsbelowtherecommendedstallspeedsisofutmostdangeroflosingcontroloftheaircraft.

[REC-33] Itmustbeassuredthatapilotiswarnedofactionsthatcouldleadtoanimmediatelossofcontrol.Alternativemeasuresshallbeenforcedtoavoidinitiatingunsafeactions.

[SC-36_HOU] ATCcontrollersshallbeinformedwherethewindsensorsarelocatedtoassigntheactualwindproperly.

[REC-34] ATCcontrollersshallbeinformedaboutthelocationofmeteorologicalsensorsandtheapplicabilityofitsdata.

[SC-37_Pilot] Performingactiveflightdutiesundertheinfluenceofprescribedmedication,whichhasnotbeenaeromedicallyprescribed,shallbestrictlyprohibited.

referto[REC-12].

[SC-38_Pilot] Theimportanceofproperflightplanningandpreparationshallbeemphasized.

[REC-35] Pilotsshallbedisciplinedthatthepreparationofaproperflightplanningincludingriskassessmentisofutmostimportanceforthesafetyofflight.

[SC-39_Pilot] Riskassessmentshallbeperformedbeforeandregularlyduringaflighttobepreparedforrapidlychangingconditionsinthedynamicaviationenvironment.

[REC-36] Pilotsdecision-makingpre-flightandin-flight(withemphasizetorapidlychangingconditionsinthedynamicaviationenvironment)shallberelatedtoariskassessmentprocess,whichistrainedregularly.

[SC-40_Pilot] PilotsshallbetrainednottoacceptATCclearancescausingworkload,whichisexceedingthepersonalcapabilities.

[REC-37] PilotsshallbedisciplinedthatthePIChasthefinalauthorityforthesafetyofflight.Therefore,clearancesshallalwaysbeverifiedinrespectofsafetydeficiencies.Regularscenario-basedtrainingeventsindecision-makingandassertivenessshallbearequirement.

[SC-41_Pilot] Safety-relevantmaneuversshallbeperformedstrictlyaccordingtoprocedures.

[REC-38] Pilotsshallbestrictlydisciplinedthatitiseachairman’spersonalresponsibilitytomaintainskillstobepreparedinperformingsafety-relevantmaneuversanytimetheyareneeded.

[SC-42_Pilot] Theimportanceofsterilecabinproceduresshallbeemphasized.

[REC-39] Pilotsshallbeawarethatdistractionsmayseverelyimpairthesituationalawareness.Passengersmustbebriefedaboutsterilecabinprocedures.Placardstoremindintheaircraftcabinshallbeconsidered.

[SC-43_Pilot] Methodsandproceduresforrecognizingandregaininglostsituationalawarenessshallbetaught.

[REC-40] Pilotsoperatinginsingle-pilotoperationshallbeawarethat“stayingaheadoftheaircraft”allthetimeisofutmostimportance.IfalackofsituationalawarenessisrecognizedprocedurestoregainSAshallbeknownandappliedaccordingly.

[SC-44_Pilot] Communicationannouncementsshallbeperformedaftertheflightpathissafelystabilized(“aviate-navigate-communicate”procedure).

[REC-41] Itmustbethegoldenruleforanypilot,thatfirststabilizingtheflightpathandsecondnavigation(adherencetoATCclearances)haspriorityovercommunication.

[SC-45_Pilot] TheimportanceofSRMtrainingcoursesshallbeemphasizedtoprovideprocedurestocopewithhighworkloadsituations.

[REC-42] Considerationofallavailableresourcesmustbeperformed.Regularscenario-basedtrainingtoenhancethehighestachievablelevelofcompetenceshallbeemphasized.Workloadshallalwaysbemanagedinawaysoastomaintainsufficientpersonalcapacitiesforsafecompletionsofprimaryflightduties.

TUGrazIMasterthesis

Results

73

Safetyconstraints Safetyrecommendations[SC-46_Pilot] IfATCrequestscannotbecompliedwith,

proceduresforenergyandATCmanagementshallbeenforced.

[REC-43] Stabilizedapproachcriteriashallbemonitoredbythepilot.Appropriatewarnings(“attention-getters”)shallbetriggeredbytheon-boardavionicsequipmentincaseofparametersdeviating.

[SC-47_Pilot] Proceduresforcorrectairspeedcontrolandsubsequentaircrafttrimshallbeenforced.

[REC-44] Pilotsshallbeawarethatirrespectiveofthelevelofautomationofanaircraft,thedisciplinetostrictlyfollowapprovedproceduresandmaintainbasicskillsinflyingisrequiredforasafeoperation.

[SC-48_Pilot] Procedurestocopewiththeinfluenceofvisualillusionsshallbeenforced.

[REC-45] Pilotsshallbeawarethatvisualperceptioninfluencesthepilot’sbasicflyingcapability.Vigilanceandregulartrainingshallbeensured.

[SC-49_Pilot] Proceduresfortheconsiderationofvisualglideslopeindications(PAPI)shallbeenforced.

[REC-46] Effectsofvisualillusionsinrespectofstabilizedapproachcriteriashallnotbeunderestimatedandregularlytrained.

[SC-50_Pilot] Procedurestoperformproperenergymanagement(powercontrol,side-slipmaneuvers)tocomplywithstabilizedapproachcriteriashallbeemphasized.

referto[REC-44]

[SC-51_Pilot] Pilotsshallknowtoavoidhighbankanglesinlowlevelflying.

[REC-47] Highbankawarenesssystemsshallbeintegratedintheaircraft’savionicssystem,towarnpilotsexceedingdefinedbankangles.

[SC-52_Pilot] Navigationalchartsmustbeeasytoreadandhaveabackup.

[REC-48] Pilotsshallassurethatthenavigationalchartsusedcanbereadandunderstoodunderallexpectedconditions.

[SC-53_Pilot] Proceduresmustbeenforcedthatpilotsoncontrolarealwaysawarewhenandhowtoinitiateago-aroundtomaintainthehighestachievablelevelofsafetymargin.

referto[REC-38]

[SC-54_Pilot] Apilotmustbeabletoperformacorrectgo-aroundprocedureinanysituation,irrespectiveofexternalinfluences.

referto[REC-38]

[SC-55_Pilot] Theinfluenceofwindcomponentsinperformanceshallneverbeunderestimated.

[REC-49] Pilotsshallbetrainedhowtodealwithenvironmentalfactorsinstantaneouslyinfluencingtheenergystateoftheaircraft.

[SC-56_Pilot] Measuresshallbeenforcedtomaintainthehighestlevelofsituationalawareness.

referto[REC-26]

[SC-57_Pilot] Procedurestoavoidandescapelossofaircraftcontrolshallalwaysbethefirstpriorityofanypilot.

[REC-50] Pilotsshallalwayshavefullcontroloftheaircraft.Forthecaseofinadvertentlossofcontrol,thepilotshallbetrainedregularlytoapplythesafestcoursesofaction.

[SC-58_Paxe] Passengersshallbeawareofsterilecabinproceduresandavoiddistractingthepilot.

referto[REC-39]

[SC-59_Paxe] PassengersshallbeconsideredasaresourceinSRM.

[REC-51] Designatedpassengersshallbeconsideredtoassistthepilotinresourcemanagement(e.g.readingchecklists,announcingdeviationsofbasicflightparameters,etc.).

[SC-60_Paxe] Pilotsshallbetrainedinprocedurestoprovideasafeandcomfortableatmosphereforpassengers.

[REC-52] Passengersshallbebrieflykeptinformedabouttheprogressofflightwithavoidinganymeansofscare.

[SC-61_Paxe] AnybodyonboardshallknowaboutactivatingCAPS,iflife-threateningsituationspersist(whichrequiresdetailedpreflghtbriefingforpassengers).

[REC-53] Passengersshallbebriefedaboutlife-threateningsituationsrequiringCAPSactivationand/orregularlycompleteaCAPStraining.

[SC-62_Aircraft]

Aircraftsystemindicationsshallbesimpletounderstandandread.

[REC-54] Aircraftsystemsshallbedesignedinawaythattheysupportthedecision-makingprocessratherthanimpairitbyanoverloadofdata.

TUGrazIMasterthesis

Results

74

[SC-63_Aircraft]

ProceduresofactivatingCAPSinlife-threateningsituationsshallbebroughttonoticeableattentioninthecabin.

[REC-55] Optionstoactivateapplicablepassivesafetyequipmentshallalwaysbeconsideredandmentionedinpersonalpilotbriefings.Appropriateindicationsbytheon-boardavionicssystemmayreducethetimeofpossiblestartleeffects.

Table3-1Safetyrecommendations

TUGrazIMasterthesis

Results

75

The existing accident report does not contain all necessary information to gain a holistic

understanding of the prevailing loss. Through the STAMP (Leveson, 2011) modeling subsequently

questionsemerged (refer toTable3-2Questions raised). Itsanswerswouldneed tobeconsidered

for further clarification in the CAST (Leveson, 2011) analysis and would probably involve revising

already-definedsafetyconstraintsandrecommendations.

Questionsraised

[QR-1] Arethereanyincidentsknowntotheauthorityinrespectoftheaccidentpilot?

[QR-2]Statedetailsabouttheinitialtrainingoftheaccidentpilotandherprogress(type/duration,typesofaircraft,detailsaboutdescentplanning,energymanagement,busyairportoperations,stabilizedapproachcriteria,stall/spinavoidance,CAPS)?

[QR-3] Whatwasthestatus/progressoftheaccidentpilot’sinstrumenttraining?

[QR-4] Whathadbeentheweaknessesoftheaccidentpilot,intheopinionoftheCFIs?

[QR-5] Wasgoodairmanshipinrespectofspinavoidance(asmentionedinthePOH)trained?

[QR-6] WastheFOMwiththe“EnvelopeofSafety”taughtaspartoftheinitialtrainingfortheCirrusaircraft?

[QR-7] DidthepilotattendanycoursesinSRMorrelatedtopicsandwhathadbeenthecontent?

[QR-8] Howwasthepilot’sattitudeinrespectofherownsafetyculture?

[QR-9] Wastheaccidentpilottrainedtorecognizelossofcontrolsituationsandhowtoescape?

[QR-10] WhichcommunicationprocessesattheHOUATCFacilityrequireimprovements?

[QR-11] WaspeerpressureinfluencingthecommunicationbetweentheATCtraineeandhisinstructor?

[QR-12] Whichalternativeprocedures(exceptvisualseparation)forre-aligningaircraftinthetrafficpatternwerecommon?

[QR-13] AretheATCcontrollerstrainedtofollowICAOstandardphraseologyandavoidunnecessarilylongATCclearances,especiallyduringcriticalphasesofflight?

[QR-14] DotheLCcontrollershaveadequatetrainingforvectoringaircraftinthenearproximityoftheairportunderhigh-trafficconditions?

[QR-15] WasLCcontroleverindoubt,thatN4252Gmightnotbeabletolandtheaircraftsuccessfully?

[QR-16] HowdoesanATCcontrollerevaluatetheconfidenceofpilots?

[QR-17] DidtheLCCanticipatethehighworkloadandstressthatthepilotofN4252Gwasunderatthethirdgo-around?

[QR-18] Howwasassured,thattheLCCtakingoverhadsufficientsituationalawarenessabouttheATCtrafficsituation?

[QR-19] HowisitassuredthatindividualproceduresandworkingpracticesaresharedamongeveryATCteammember?

[QR-20] HowwastheperformanceofATCcontrollersassured?

[QR-21] WhatschedulestheissueofnewPOHrevisions?

[QR-22] WhatisthealternativeprocedureforpilotsiftheCAPSsystemcannotbeactivatedincaseofanunintendedspin?

[QR-23] Wasthepilotawareoftheassociatedrisksdueartificialaerodynamicforcesonthecontrolyoke?

[QR-24] HowdoesthemanufacturerassurethatLOCisavoidedinCirrusaircraft?

[QR-25] DidtheaccidentpilotparticipateinanyCPPPtraining?

TUGrazIMasterthesis

Results

76

Questionsraised

[QR-26] DidtheaccidentpilotparticipateinanyCDMseminar?

[QR-27] DidanyofthepassengersparticipateinaPartnerinCommandseminar?

[QR-28] DidtheactualNOTAMsatthedayofaccidentstateanydeficienciesinfluencingthesafetyofflight(e.g.unserviceabilityofPAPI,displacedthresholds,etc.)?

[QR-29] Underwhichpre-requisitesdidtheoperator/aircraftownerpermitthepilottooperatetheaircraft?

[QR-30] Whatwastheoperator’s/aircraftowner’ssafetypolicy(requirements,currency,training)forpilotsoperatingtheaircraft?

[QR-31] Whatarethedetailsconcerningtheaccidentpilot’stypesofaircraftflown,flighthoursandlandings?

[QR-32] DidthepilothaveaflightplanningpackageincludingweatherforecastandNOTAMs?

[QR-33] Didtheaccidentpilotapplyanyriskassessmenttools?

[QR-34] Didthepilotwaitatleast24hoursaftertakingZolpidembeforeherflyingactivity(asrecommendedbytheFAA)?

[QR-35] Howdidthepilotpreparefortheflightandwhathadbeenthecontentsoftheflightplanningpackage?

[QR-36] Whatwasthepilot’sattitudeinrespectofriskassessment?

[QR-37] Didthepilotperformanytrainingflightsoraflightreviewbeforetheaccident?

[QR-38] Wasthepilot’slevelofsituationalawarenessimpairedbyanyreasonandcouldthepilotingeneralbedistractedeasilywhenperformingtasks?

[QR-39] WasthepilottrainedinSRM?

[QR-40] Hadthepilotbeensubjecttotimepressure(appointment)onthedayoftheaccident?

[QR-41] Didthepilotactivelyoperateonothertypesofaircraftintherecentpast?

[QR-42] Wasthepilotapplyingcorrecttrimprocedures?

[QR-43] ArethereanyRDMdataavailableregardingaircrafttrim?

[QR-44] Wasthepilotawareofpossiblevisualillusions?

[QR-45] Hadtherebeenanyincidentsbythepilotinrespectofunstabilizedapproachesatotherairports?

[QR-46] Wasthepilottrained/assessedforside-slipmaneuvers?

[QR-47] Whichchartshadbeenusedasreferencefornavigation?

[QR-48] Wasthepilotabletoreadthechartsproperly?

[QR-49] Whatwasthereasonforapplyingreducedpowersettingsforthego-around?

[QR-50] Wasthepre-flightcheckincl.stallwarningsystemcheckperformedproperly?

[QR-51] DidATCrecordanystallwarningsignalsonthetransmissiontapes?

[QR-52] DoestheRDMstoreanactivestallwarningtrigger?

[QR-53] DidthepilotperformanyCAPStraining?

[QR-54] Wereanyofthepassengersontheflightundertimepressure?

[QR-55] Wereanyofthepassengersknownforairsicknessorotherphysiologicaldeficiencies?

[QR-56] Hadpassengersbeenbriefedonsterilecabinprocedures?

[QR-57] Didthepassengersfrequentlyflywithsingle-enginepistonaircraftand/orhaveextensiveaviationknowledge?

TUGrazIMasterthesis

Results

77

Questionsraised

[QR-58] Hadthepassengersbeenbriefedaboutlife-threateningsituationsrequiringtheactivationofCAPS?

[QR-59] Wasthestallwarningsystemfunctionableontheaccidentflight?

[QR-60] Wasthepilotawareofaerodynamicaircraftreactionswhenapproachingstallconditions?

[QR-61] WasthereanyfailureoftheprimaryflightdisplaysloggedbytheRDM?

[QR-62] Didtheprimaryflightdisplayfailorgetinanunreadablecondition?

[QR-63] Didtheaccidentaircrafthavealternateindicationsoftheprimaryflightinformation(speed,altitude,attitude)?

[QR-64] Forwhichspeedwastheaircrafttrimmedbeforethefinalimpact?

Table3-2Questionsraised

Figure2-24summarizestheresults(unsafecontrolactions(UCA),safetyconstraints(SC),questions

raised(QR))categorizedfortheindividualcomponentsintheHCS.

Figure3-1Generalmodelofhierarchicalcontrolstructureincludingresults

Themodeling of the prevailing accident of N4252G emerged 34 unsafe control actions, 63 safety

constraints,64raisedquestionsand55safetyrecommendations.

TUGrazIMasterthesis

Discussion

78

4 DISCUSSION

The interaction ofmany factorswas crucial for this accident. The hierarchical control structure in

Chapter2.4visuallyillustratesthecomplexityofasystem-theoreticalaccidentinvestigation,whicha

linear simplification - as traditionally used inmany cases - cannot provide. The comparisonof the

results of the linear analysis (refer to F Appendix) against a STAMP/ CAST (Leveson, 2011) based

analysisclearlyshowsthedifferentresults.

The complexity in aviation is steadily increasing and the multitude of relevant terms (refer to A

Appendix)illustratesonlyafractionofthenecessaryexpertisethattoday’spilotsneed.Despitethe

constantlyimprovedtechnicalaids,aviationaccidentscontinuetohappen,althoughthesearerarely

givenpublicimportanceingeneralaviation.Thatwasalsooneofthereasonswhytheauthorchose

thisaccidentasatopicforthemasterthesis.

Theaircraftinthisaccidentwasflownintoanundesiredaircraftstate,whicheventuallycausedthe

loss. Referring to the official accident report, the question emerged concerning what aspects

contributed a pilotwithmore than 300 flight hours of type experience in just over 2 years being

involved in such an accident. The question of whether a flight review could have avoided the

accidentcannotbeclearlyanswered.

Despite the fact that the safety recommendations of this thesis include changes in standards and

regulations, the author believes that the safety of aviation is not solely governed by laws and

regulations.Anyonewhoisactivelyinvolvedinaviation-notonlypilots-mustbemadeawarethat

regulations are only the foundation upon which decisions must be continually built. “Good

airmanship”requiresmuchmorethancompliancewithlegalregulationsandtheavoidanceof“dirty

dozen”. It requiresa strongemphasisondiscipline tocontinuously improveskillsandpermanently

assessdecisionswiththeriskstofinallyexecutesafeflightoperations.

Theimplementationofsafetyrecommendations intostandards/ legal lawisoftenconsideredasan

unnecessary restriction. However, when it is recognized that every single aviation operator can

contributetoasaferaviation,itisultimatelyuptotheattitudeofindividualstoinspireotherstoact

safelyandmakeaviationsaferinthefuture.

Finally, the authorhopes that researchers andpractitioners in aviation accident investigations can

obtainvaluable insights fromthis researchmethodandfindings,andthat theuseofSTAMP/CAST

willbeestablishedasbestpracticeinaviationaccidentinvestigation.

TUGrazIMasterthesis

Conclusions

79

5 CONCLUSIONS

ThisthesisprovidesaninsightfulinvestigationofthisspecificaccidentbyapplyingLeveson’sSTAMP

model and CAST methodology (Leveson, 2011). Compared with a conventional method of

investigation,theinsightsgainedandlessonslearnedfromthisstudy,althoughonlylimitedsources

ofinformationhadbeenavailabletotheauthor,highlightthepotentialinapplyingSTAMPinmodern

accidentinvestigations.

The influences of individual components were analysed and described. It was emphasized that

complex,system-theoreticalmodelscanalsobejustifiedbymeansofshortandsimplestatements.

The large number of identified recommendations illustrates the existing potential for revising

procedures in aviation. The questions raised describe that the present aviation accident could be

investigatedandunderstoodinfurtherdetailbyansweringtheseopenquestions.

Theexistingaccidentreportwassubstantiatedbytheinvestigatingpartythroughcontributingfactors

butdidnotelaboraterecommendationsforpreventingfutureaircraftaccidents.Thehighercontrol

levels had influenced the outcome by a variety of contextual factors. It was not possible to

investigate indetail forwhatreasontheowneroftheaircraftpermittedtheoperationbythepilot

withoutavalidflightreview.Despitethehighworkloadandexternalinfluences,thepilotappliedhis

habits,whichheobviouslydidnotclassifyasunsafeandthereforecontinued.Similarly, itwasalso

not obvious to ATC that applied habits deviating from known procedures would limit safety.

Information from the training organisation was limited to statementsmade by two of the pilot’s

flight instructors and a number of questions remained unanswered. The extent to which the

manufacturer'sflightcontrolsystemtookeffectremainsquestionable,andtheextenttowhichCOPA

provided training courses to the pilot and passengers was not apparent due to the lack of

information. Restrictions fromHOU airport could not be researched. Finally,when aircraft control

waslost,thepassivesafetyaidCAPSwasnotactivated.

The assumption is confirmed that the accident was still favored by the interaction of individual

controllers.Thisconcludesthatregularadaptingtheaviationsystemisrequiredinsofarthatitdoes

notblamethemistakesofanindividual.Recommendationsaretobeimplementedtoensurethatin

the interaction of unsafe control actions under worst-case environmental conditions through

individualcomponents,theresultisnotanaccident.

TUGrazIMasterthesis

References

80

6 REFERENCES

AOPATechnologicallyAdvancedAircraft,S.a.(2007).TechnologicallyAdvancedAircraft,SafetyandTraining.AirSafetyFoundation.

AOPA.org.(2019,January05).retrievedfromhttps://www.aopa.org/training-and-safety/Students/presolo/skills/entering-the-traffic-pattern.

Endsley,M.(2000).SituationAwarenessAnalysisandMeasurement.Routledge.

Endsley,M.(2011).DesigningforSituationAwareness.

FAA.gov.(2019,January05).retrievedfromhttps://www.faa.gov/training_testing/training/fits/more/.

FAA.gov.(2019,January04).retrievedfromhttps://www.faa.gov/training_testing/training/pilot_schools/.

FAAsafety.gov.(2019,January05).retrievedfromhttps://www.faasafety.gov/WINGS/pub/learn_more.aspx.

FOM-SR20,C.(2011).FlightOperationsManual.ReissueA.(C.D.Corporation,Ed.)Duluth.

HOU-ATCT-0064.(2018).HOUTowerAccidentPackageN4252G.Houston,TX.

ICAO.(2005,July).Annex2totheConventiononInternationalCivilAviation.RulesoftheAir.Montreal:InternationalCivilAviationOrganisation.

ICAO.(2007).Doc.9432,ManualofRadioTelephony.FourthEd.InternationalCivilAviationOrganisation.

ICAO.(2011).Doc.9962,ManualonAccidentandIncidentInvestigationPoliciesandProcedures.FirstEd.InternationalCivilAviationOrganisation.

ICAO.(2013,July).Annex19totheConventiononInternationalCivilAviation.SafetyManagement.Montreal:InternationalCivialAviationOrganisation.

ICAO.(2016,July).Annex11totheConventiononInternationalCivilAviation.AirTrafficServices.Montreal:InternationalCivialAviationOrganisation.

ICAO.(2016,July).Annex13totheConventiononInternationalCivilAviation.AircraftAccidentandIncidentInvestigation.Montreal:InternationalCivilAviationOrganisation.

ICAO.(2016,July).Annex6totheConventiononInternationalCivilAviation.OperationofAircraft,PartII.Montreal:InternationalCivilAviationOrganisation.

Jeppesen.(2018,November27).NorthAmericaAirwayManual.

Kern,T.(1996).RedefiningAirmanship.

TUGrazIMasterthesis

References

81

Koglbauer,I.(2018).TheTippingPointofSTAMP.AviationPsychologyandAppliedHumanFactors,8(2),p.131-133.

Leveson,N.(2011).EngineeringaSaferWorld.(T.M.Press,Ed.)Cambridge,Massachusetts,USA.

Leveson,N.(2018).STPAHandbook.(N.Leveson,Ed.)retrievedfromhttp://psas.scripts.mit.edu/home/.

NTSB.(2013,March).PreventAerodynamicStallsatLowAltitude.Rev.12-2015.

NTSB.(2016,December23).AirTrafficControl,GroupChairman'sFactualReport,CEN16FA211.Montreal:NationalTransportationSafetyBoard.

NTSB.(2017,December12).AviationAccidentFinalReport.N4252G.

NTSB.(2017,April04).CockpitDisplay(s)-RecordedFlightData.WashingtonDC.

PassengerRecherches.(2019,January05).retrievedfromhttp://www.kathrynsreport.com/2016/06/cirrus-sr20-n4252g-safe-aviation-llc.html.https://www.dailymail.co.uk/news/article-3636188.

POH-SR20,C.(2015).Pilot'sOperatingHandbookandFAAapprovedAirplaneFlightManual.RevisionA1.(C.D.Corporation,Ed.)Duluth.

Skybrary.aero.(2018,November30).retrievedfromhttps://www.skybrary.aero/index.php/APR.

Skybrary.aero.(2019,January04).retrievedfromhttps://www.skybrary.aero/index.php/National_Transportation_Safety_Board_(USA)_(NTSB).

Skybrary.aero.(2019,January04).retrievedfromhttps://www.skybrary.aero/index.php/Federal_Aviation_Administration_(FAA).

Skybrary.aero.(2019,January05).retrievedfromhttps://www.skybrary.aero/index.php/Startle_Effect.

Skybrary.aero.(2019,January05).retrievedfromhttps://www.skybrary.aero/index.php/The_Human_Factors_%22Dirty_Dozen%22.

Skybrary.aero.(2019,January05).retrievedfromhttps://www.skybrary.aero/index.php/The_Human_Factors_%22Dirty_Dozen%22#Lack_of_assertiveness.

Skybrary.aero.(2019,January05).retrievedfromhttps://www.skybrary.aero/index.php/Vigilance_in_ATM.

Stringfellow,M.(2010).HumanandOrganisationalFactorsinAccidents.Boston,US:MIT.

Team,F.S.(2016,August).FlytheAircraftFirst.AFS-85016-08.

USDepartmentofTransportation,F.(2011).AC61-91J.WINGS-PilotProficiencyProgram.

USDepartmentofTransportation,F.(2016).Pilot'sHandbookofAeronauticalKnowledge.

TUGrazIMasterthesis

References

82

USDepartmentofTransportation,F.(2017,12).AeronauticalInformationManual.

USDepartmentofTransportation,F.(2018,April30).AC61-98D(supersedesAC61-98C).CurrencyRequirementsandGuidancefortheFlightReviewandInstrumentProficiencyCheck.

Wikipedia.org.(2019,January04).retrievedfromhttps://en.wikipedia.org/wiki/Cirrus_Aircraft.

Wikipedia.org.(2019,January04).retrievedfromhttps://en.wikipedia.org/wiki/Cirrus_SR20.

Wikipedia.org.(2019,January04).retrievedfromhttps://en.wikipedia.org/wiki/William_P._Hobby_Airport.

TUGrazIMasterthesis

AAppendix

A-1

APPENDIXA

DefinitionofRelevantTerms

Inordertounderstandthetermsusedinthisthesis,thisappendixprovidesa listofdescriptionsof

themost common terms used. It is important to note that these terms and their definitions are

typicallynot self-explanatoryanddonothaveanyaccepteddictionarydefinitions, andhence they

areonlyapplicableinthedocumentinwhichtheyaredefined.

Accident.“Anoccurrenceassociatedwiththeoperationofanaircraftwhich,inthecaseofamanned

aircraft,takesplacebetweenthetimeanypersonboardstheaircraftwiththeintentionofflightuntil

suchtimeasallsuchpersonshavedisembarked,orinthecaseofanunmannedaircraft,takesplace

betweenthetimetheaircraftisreadytomovewiththepurposeofflightuntilsuchtimeasitcomes

torestattheendoftheflightandtheprimarypropulsionsystemisshutdown,inwhich:

a)apersonisfatallyorseriouslyinjuredasaresultof:

• beingintheaircraft,or

• direct contact with any part of the aircraft, including parts which have become detached

fromtheaircraft,or

• directexposuretojetblast,exceptwhentheinjuriesarefromnaturalcauses,self-inflictedor

inflictedbyotherpersons,orwhen the injuries are to stowawayshidingoutside theareas

normallyavailabletothepassengersandcrew;or

b)theaircraftsustainsdamageorstructuralfailurewhich:

• adverselyaffectsthestructuralstrength,performanceorflightcharacteristicsoftheaircraft,

and

• wouldnormallyrequiremajorrepairorreplacementoftheaffectedcomponent,exceptfor

engine failure or damage, when the damage is limited to a single engine (including its

cowlings or accessories), to propellers, wing tips, antennas, probes, vanes, tires, brakes,

wheels, fairings, panels, landing gear doors, windscreens, the aircraft skin (such as small

dents or puncture holes), or for minor damages to main rotor blades, tail rotor blades,

landinggear,andthoseresultingfromhailorbirdstrike(includingholesintheradome);or

c)theaircraftismissingoriscompletelyinaccessible.

Note1-Forstatisticaluniformityonly,aninjuryresultingindeathwithin30daysofthedateofthe

accidentisclassified,byICAO,asafatalinjury.

Note2-Anaircraftisconsideredtobemissingwhentheofficialsearchhasbeenterminatedandthe

wreckagehasnotbeenlocated”(ICAO,Annex13,2016,p.1-1).

TUGrazIMasterthesis

AAppendix

A-2

Airmanship. “Airmanship is the consistent use of good judgement and well-developed skills to

accomplishflightobjectives.Thisconsistencyisfoundedonacornerstoneofuncompromisingflight

discipline and is developed through systematic skill acquisition and proficiency. A high state of

situationalawarenesscompletestheairmanshippictureandisobtainedthroughknowledgeofone’s

self,aircraft,environment,teamandrisk”(Kern,1996,p.22).

Assertiveness. “Assertiveness is a communication and behavioral style that allows us to express

feelings,opinions,concerns,beliefsandneeds inapositiveandproductivemanner.[…]Beingboth

unabletoexpressourconcernsandnotallowingothertoexpresstheirconcernscreatesineffective

communications and damages teamwork. Unassertive teammembers can be forced to go with a

majoritydecision,evenwhentheybelieveitiswronganddangeroustodoso”

(Skybrary.aero,retrievedfrom

https://www.skybrary.aero/index.php/The_Human_Factors_%22Dirty_Dozen%22#Lack_of_assertive

ness,2019).

Causes.“Actions,omissions,events,conditions,oracombinationthereof,whichledtotheaccident

orincident.Theidentificationofcausesdoesnotimplytheassignmentoffaultorthedetermination

ofadministrative,civilorcriminalliability”(ICAO,Annex13,2016,p.1-2).

Control Structure. “A control structure captures functional relationships and interactions by

modelingthesystemasasetoffeedbackcontrolloops.Thecontrolstructureusuallybeginsatavery

abstract level and is iteratively refined to capturemore detail about the system” (Leveson, STPA

Handbook,2018,p.14).

DirtyDozen.“TheDirtyDozenrelatedtoaviationreferstotwelveofthemostcommonhumanerror

preconditions, or conditions that can act as precursors, to accidents or incidents. These twelve

elementsinfluencepeopletomakemistakes.[…]

• LackofCommunication:Poor communicationoftenappearsat the topof contributingand

causal factors in accident reports, and is therefore one of themost critical human factor

elements[…]

• Complacency:Complacencycanbedescribedasafeelingofself-satisfactionaccompaniedby

alossofawarenessofpotentialdangers[…]

• LackofKnowledge:[…]

• Distraction:Distractioncouldbeanythingthatdrawsaperson’sattentionawayfromthetask

[…]

TUGrazIMasterthesis

AAppendix

A-3

• LackofTeamwork:Inaviationmanytasksandoperationsareteamaffairs;nosingleperson

(ororganisation)canberesponsibleforthesafeoutcomesofalltasks.However,ifsomeone

isnotcontributingtotheteameffort,thiscanleadtounsafeoutcomes[...]

• Fatigue: Fatigue is a natural physiological reaction to prolonged physical and/ or mental

stress[…]

• LackofResources:[…]

• Pressure:Pressureistobeexpectedwhenworkinginadynamicenvironment.[…]Pressure

canbecreatedbylackofresources,especiallytime;andalsofromourowninabilitytocope

withasituation[...]

• LackofAssertiveness:[…]Assertivenessisacommunicationandbehavioralstylethatallows

us to express feelings, opinions, concerns, beliefs and needs in a positive and productive

manner[...]

• Stress:Therearemanytypesofstress.Typically in theaviationenvironmenttherearetwo

distincttypes-acuteandchronic.Acutestressarisesfromreal-timedemandsplacedonour

senses,mentalprocessingandphysicalbody;suchasdealingwithanemergency,orworking

under timepressurewith inadequate resources. Chronic stress is accumulated and results

from long-term demands placed on the physiology by life’s demands, such as family

relations,finances,illness,bereavement,divorce,orevenwinningthelottery[…]

• LackofAwareness:Workinginisolationandonlyconsideringone’sownresponsibilitiescan

lead to tunnel vision; a partial view, and a lack of awarenessof the affect our actions can

haveonothersandthewidertask.Suchlackofawarenessmayalsoresultfromotherhuman

factors,suchasstress,fatigue,pressureanddistraction[…]

• Norms:[…]ItisimportanttounderstandthatmostNormshavenotbeendesignedtomeet

allcircumstances,andthereforearenotadequatelytestedagainstpotentialthreats”

(Skybrary.aero,retrievedfrom

https://www.skybrary.aero/index.php/The_Human_Factors_%22Dirty_Dozen%22,2019).

FITS(FAAIndustryTrainingStandards).“FITSisfocusedontheredesignofgeneralaviationtraining.

Instead of training pilots to pass practical test, FITS focuses on expertly manage real-world

challenges.Scenariobasedtraining isusedtoenhancetheGApilots’aeronauticaldecisionmaking,

risk management, and single pilot resource management skills” (FAA.gov, retrieved from

https://www.faa.gov/training_testing/training/fits/more/,2019).

TUGrazIMasterthesis

AAppendix

A-4

Flight Review. “The purpose of the flight review required by [Title] 14 CFR part 61, § 61.56 is to

provide for a regular evaluation of pilot skills and aeronautical knowledge. Consequently, a flight

review isa routineevaluationofapilot’sability toconductsafe flight. Ineffect, it isaproficiency-

basedexerciseinwhichtheairmanisrequiredtodemonstratethesafeexerciseoftheprivilegesof

hisorherpilotcertificate.[…]theflightreviewisnotatestorcheckride,butratheratrainingevent

inwhichproficiencyisevaluated.[…]Under§61.56(c)nopersonmayactasPICofanaircraft,except

asprovided in§61.56(d), (e),and(g),unlesswithinthepreceding24calendar-monthsthatperson

hasaccomplishedasatisfactoryflightreviewinanaircraftforwhichthatpilotisappropriatelyrated.

Anauthorizedinstructororotherpersonapprovedmustconducttheflightreview.[…]apersonwho

hassatisfactorilycompletedoneormorephasesoftheFAA-sponsoredWINGSwithinthepreceding

24calendar-monthsdoesnotneedtoaccomplishtheflightreviewrequirementsofthissection.[…]

Pilotsandflightinstructorsshouldbeawarethat,under§61.56(d),thereisnorequirementforpilots

whohavecompletedcertainproficiencychecksandratingswithinthepreceding24calendar-months

to accomplish a separate flight review. [...] Before beginning the flight portion of the bi-annually

[biennially]requiredflightreview,theflightinstructorshoulddiscussvariousoperationalareaswith

the pilot. This oral review should include, but not be limited to, areas such as aircraft systems,

speeds, performance, meteorological and other hazards (e.g. wind shear and wake turbulence),

operations in controlled airspace, and abnormal and emergency procedures. The emphasis during

this discussion should be on practical knowledge of recommended procedures and regulatory

requirements. […] Regardless of the pilot’s experience, the flight instructor should review at least

those maneuvers considered critical to safe flight, such as: takeoffs, stabilized approaches to

landings, slow flight, stall recognition, stalls, and stall recovery, spin recognition and avoidance,

recovery fromunusualattitudesandoperating theaircraftby sole reference to instrumentsunder

actual or simulated conditions” (USDepartment of Transportation, AC 61-98D (supersedes AC 61-

98C),2018,p.4-1,4-2,4-6,4-7).

GeneralAviationOperation.“Anaircraftoperationotherthanacommercialairtransportoperation

oranaerialworkoperation”(ICAO,Annex6,PartII,2016,p.1.1-4).

Hazard.“Ahazardisasystemstateorsetofconditionsthat,togetherwithaparticularsetofworst-

caseenvironmentalconditions,willleadtoaloss”(Leveson,STPAHandbook,2018,p.17).

TUGrazIMasterthesis

AAppendix

A-5

IMSAFE. “One of the best ways single pilots can mitigate risk is to use the IMSAFE checklist to

determinephysicalandmentalreadinessforflying.[...]IMSAFE,whichstandsforIllness,Medication,

Stress, Alcohol, Fatigue, and Emotion“ (US Department of Transportation, Pilot’s Handbook of

AeronauticalKnowledge,2016,p.2-8,17-18).

Investigation. “A process conducted for the purpose of accident prevention which includes the

gathering and analysis of information, the drawing of conclusions, including the determination of

causesand/orcontributingfactorsand,whenappropriate,themakingofsafetyrecommendations”

(ICAO,Annex13,2016,p.1-2).

Loss.“Alossinvolvessomethingofvaluetostakeholders.Lossesmayincludealossofhumanlifeor

humaninjury,propertydamage,environmentalpollution,lossofmission,lossofreputation,lossor

leakof sensitive information,oranyother loss that isunacceptable to thestakeholders” (Leveson,

STPAHandbook,2018,p.16).

LossofControl.“LOCreferstoaircraftaccidentsthatresult fromsituations inwhichapilotshould

havemaintained(orshouldhaveregained)aircraftcontrol,but failedtodoso”(USDepartmentof

Transportation,AC61-98D(supersedesAC61-98C),2018,p.2-1).

Notices to Airmen (NOTAMs). “Notices to Airmen, or NOTAMs, are time-critical aeronautical

informationeithertemporaryinnatureornotsufficientlyknowninadvancetopermitpublicationon

aeronautical charts or in other operational publications. The information receives immediate

disseminationviatheNationalNoticetoAirmen(NOTAM)System.NOTAMscontaincurrentnotices

toairmenthatareconsideredessentialtothesafetyofflight,aswellassupplementaldataaffecting

otheroperationalpublications”(USDepartmentofTransportation,Pilot’sHandbookofAeronautical

Knowledge,2016,p.1-12).

PAVE checklist. “By incorporating the PAVE checklist into preflight planning, the pilot divides the

risks of flight into four categories: Pilot-in-command (PIC), Aircraft, enVironment, and External

pressures (PAVE) which form part of a pilot’s decision-making process” (US Department of

Transportation,Pilot’sHandbookofAeronauticalKnowledge,2016,p.2-8).

TUGrazIMasterthesis

AAppendix

A-6

Pilot’s Operating Handbook/ Airplane Flight Manual (POH/ AFM)16. “FAA-approved documents

publishedbytheairframemanufacturer that list theoperatingconditions foraparticularmodelof

aircraft” (USDepartment of Transportation, Pilot’sHandbookof Aeronautical Knowledge, 2016, p.

G23).

PilotinCommand(PIC).“Thepilotdesignatedbytheoperator,orinthecaseofgeneralaviation,the

owner,asbeingincommandandchargedwiththesafeconductofaflight”(ICAO,Annex2,2005,p.

1-7).TheCodeofFederalRegulationsdeclares that“thepilot incommandofanaircraft isdirectly

responsible for, and is the final authority as to, the operation of that aircraft. […] In an in-flight

emergencyrequiringimmediateaction,thepilotincommandmaydeviatefromanyruleofthispart

totheextentrequiredtomeetthatemergency” (rf.Title14oftheCodeofFederalRegulations(14

CFR)part91,§91.3).

PrecisionApproachPathIndicator(PAPI).ReferringtotheAIM(2017)aPAPI isdefinedasavisual

aid of one row of lights in two- or four-light systems arranged to provide descent guidance

informationduringtheapproachtotherunway.Apilotonthecorrectglideslopewillseetwowhite

lights and two red lights (rf. (USDepartment of Transportation, Aeronautical InformationManual,

2017,p.2-1-1,2-1-4)).

Safety constraint. “A system-level safety constraint specifies system conditions or behaviors that

needtobesatisfiedtopreventhazards(andultimatelyprevent losses)” (Leveson,STPAHandbook,

2018,p.20).

Safety recommendation. “A proposal of an accident investigation authority based on information

derived from an investigation, made with the intention of preventing accidents or incidents and

which innocasehasthepurposeofcreatingapresumptionofblameor liabilityforanaccidentor

incident. In addition to safety recommendations arising from accident and incident investigations,

safetyrecommendationsmayresultfromdiversesources,includingsafetystudies”(ICAO,Annex19,

2013,p.1-3).

Safety risk. “Thepredictedprobabilityandseverityof theconsequencesoroutcomesofahazard”

(ICAO,Annex19,2013,p.1-3).

16Title14 of the Code of Federal Regulations (14 CFR) part 91, §91.9 requires that pilots comply with theoperatinglimitationsspecifiedintheapprovedflightmanuals,markings,andplacards.

TUGrazIMasterthesis

AAppendix

A-7

Single-PilotResourceManagement(SRM).“Itistheabilitytomanagealltheresourcesavailabletoa

singlepilottoensurethatthesuccessfuloutcomeoftheflightisneverindoubt”(FOM-SR20,2011,p.

3-2).

SituationalAwareness (SA).ReferringtoEndsley (2000),situationalawareness is theperceptionof

elementsintheenvironmentwithinavolumeoftimeandspace,thecomprehensionoftheirmeaning

andtheprojectionoftheirstatusinthenearfuture17.SAisthereal-worldchangingknowledgethatis

critical foreffectivedecision-makingandaction.TheformaldefinitionofSAbreaksdown intothree

separatelevels:

Level1–perceptionofelementsintheenvironment18

Level2–comprehensionofthecurrentsituation19

Level3–projectionoffuturestatus

(rf.(Endsley,SituationAwarenessAnalysisandMeasurement,2000,p.13-14)).

StabilizedApproachCriteria.“[…]theairplaneshouldbestabilizedby500ftaboveairportelevation

during straight-in approaches in visual meteorological conditions (VMC). Pilots should monitor at

leastsevenmajorelementsthatdefineastabilizedapproachinaGAairplane.TheFAAconsidersan

approach to touchdowntobestabilizedwhentheairplanemeetsallof the followingcriteria,with

onlyminordeviations:

[…]Glidepath.Theairplane ison thecorrect flightpath.Typically, theglidepath is3degrees to the

runwaytouchdownzone(TDZ)(obstructionspermitting).

[…]Heading.Theairplaneistrackingtheextendedcenterlinetotherunwaywithonlyminorheading/

pitchchangesnecessarytocorrectforwindorturbulencetomaintainalignment.Bankangleshould

notexceed15degreesonfinalapproach.

[…] Airspeed. The pilotmaintains a constant target airspeedwithin +10/ -5 kts indicated airspeed

(KIAS),whichisusuallyat,butnolowerthan,therecommendedlandingspeedspecifiedinthePOH

[…] Note: […] Pilots generally select an appropriate approach speed for the prevailing weather,

aircraft,traffic,andperformanceconditions,butnotlessthan1.3Vs0.However,aircraftareusually

slowedtoanormallandingspeedwhenonthefinalapproachjustpriortolanding.

17pilotsusuallycallitto“stayaheadoftheaircraft”18influencesmay be channelized attention (tunnel vision), distraction and task saturation (rf. (Kern, 1996, p.234))19newpilotsmighthavedifficultiesdevelopingSAatthislevelorbeyond,astheyhavefewexperientialpatternsonwhichtoplacenewinformationofevents(rf.(Kern,1996,p.236))

TUGrazIMasterthesis

AAppendix

A-8

[…]Configuration.Theairplaneisinthecorrectlandingconfigurationwithflapsasrequired,landing

gearextended,andtheairplaneintrim.

[…]RateofDescent.Descentrateisaconstantandgenerallynogreaterthan500fpm.Ifadescent

greaterthan500fpmisrequiredduetoapproachconsiderations,itshouldbereducedpriorto300ft

abovegroundlevel(AGL)andwellbeforethelandingflareandtouchdownphase.

[…]PowerSetting.Powersetting isappropriatefortheairplaneconfigurationand isnotbelowthe

minimumpowerforapproachasdefinedbythePOH/AFM.

[…] Checklists/ Briefings. All briefings and checklists (except the landing checklist) are completed

priortoinitiatingtheapproach.

Note:ForatypicalGApistonairplaneinatrafficpattern,iftheapproachbecomesunstabilizedbelow

300ftAGL,thepilotshouldinitiateanimmediatego-around”(USDepartmentofTransportation,AC

61-98D(supersedesAC61-98C),2018,p.2-3,2-4).

StartleEffect.“Inaviation,startleeffectcanbedefinedasanuncontrollable,automaticreflexthatis

elicitedbyexposure toa sudden, intenseevent thatviolatesapilot’sexpectations. […]The startle

effectincludesboththephysicalandmentalresponsestoasuddenunexpectedstimulus.Whilethe

physicalresponsesareautomaticandvirtually instantaneous,thementalresponses-theconscious

processing and evaluation of the sensory information - can bemuch slower. In fact, the ability to

process the sensory information - to evaluate the situation and take appropriate action - can be

seriouslyimpairedorevenoverwhelmedbytheintensephysiologicalresponses.[…]performanceof

more complexmotor tasksmaybe impacted forup to10 seconds” (Skybrary.aero, retrieved from

https://www.skybrary.aero/index.php/Startle_Effect,2019).

System.“Asetofthings(referredtoassystemcomponents)thatacttogetherasawholetoachieve

somecommongoal,objective,orend”(Leveson,STPAHandbook,2018,p.169).

TAA.“TechnologicallyAdvancedAircraft(TAA)areequippedwithnew-generationavionicsthattake

full advantage of computing power and modern navigational aids to improve pilot situational

awareness, system redundancy and dependence on equipment, and to improve in-cockpit

informationabout traffic,weather, airspaceand terrain” (AOPATechnologicallyAdvancedAircraft,

2007,p.2).

Traffic Pattern. A visual traffic pattern is amaneuver flown by aircraft taking-off or landingwhile

maintaining visual contact with the airfield. It comprises crosswind, downwind, base and final-leg

elements.

TUGrazIMasterthesis

AAppendix

A-9

Unsafe Control Action. “An Unsafe Control Action (UCA) is a control action that, in a particular

contextandworst-caseenvironment,willleadtoahazard”(Leveson,STPAHandbook,2018,p.35).

Vigilance. “Vigilance is a term that refers to an individual’s ability to pay close and continuous

attentiontoafieldofstimulationforaperiodoftimeandbeingwatchfulforanyparticularchanging

circumstances”

(Skybrary.aero,retrievedfromhttps://www.skybrary.aero/index.php/Vigilance_in_ATM,2019).

Wake turbulence. “When an airplane generates lift, air spills over the wingtips from the high

pressure areas below the wings to the low pressure areas above them. This flow causes rapidly

rotating whirlpools of air called wingtip vortices or wake turbulence” (US Department of

Transportation,Pilot’sHandbookofAeronauticalKnowledge,2016,p.G34).

WINGS.“TheobjectiveoftheWINGS-PilotProficiencyProgramistoreducethenumberofaccidents

inGeneralAviation(GA)byassistingairmentofindeducationalopportunitiesdesignedtohelpthem

apply the principles of risk assessment and riskmanagement (RM).When properly applied, these

principles will help mitigate accident causal factors associated with common pilot errors, lack of

proficiency, and faulty knowledge. The Federal Aviation Administration’s (FAA) purpose is to

encouragethemajorityofGApilots,throughWINGS,toengageinongoing,targetedflyingtasksand

learning activities keyed to identified risks and which are designed to mitigate those risks” (US

DepartmentofTransportation,AC61-91J,2011,p.1).

TUGrazIMasterthesis

BAppendix

B-1

APPENDIXB

LossofControlinGeneralAviation

“While maneuvering an airplane at low altitude in visual meteorological conditions (VMC), many

pilotsfail20

• toavoidconditionsthatleadtoanaerodynamicstall,

• torecognizethewarningsignsofastallonset,and

• toapplyappropriaterecoverytechniques.

Many stall accidents that occur in VMC result when a pilot is momentarily distracted from the

primarytaskofflying,suchaswhilemaneuveringintheairporttrafficpattern,duringanemergency,

orwhenfixatingongroundobjects.Aerodynamicstallaccidentsfallintothe“lossofcontrolinflight”

category“(NTSB,SafetyAlert019,2013,p.1).

“TheGAJSCcitesLOCasoneofthesixmostcriticalandcommoncausesofGAaccidents.[…]TheFAA

remindspilotsandflightinstructorstoregularlyevaluate(andelevate)proceduresandskillstoavoid,

recognize, and recover from emergencies such as LOC. […] LOC usually occurs when pilots lack

proficiency.Conditionsexceedingpersonal skill limitationscanpresent themselvesatany timeand

can occur unexpectedly. In this event, the pilot should be able to avoid being startled, make

appropriatedecisionsinatimelymanner,andbeabletoexerciseskillsataproficiencylevelheorshe

may not have maintained or attained since acquired during initial training. This makes personal

currencyprogramsandproficiencytrainingessential. […]LOCaccidentsoftenoccurwhilepilotsare

maneuveringat lowaltitudeandairspeed,suchas inanairport trafficpattern” (USDepartmentof

Transportation,AC61-98D(supersedesAC61-98C),2018,p.2-1,2-2).

20Author’s note: “fail“ in respect of humans focuses on blame, which contradicts systemic analyses of whyhumanerrorsappearedtoberightatthetimetheyhadoccured

TUGrazIMasterthesis

CAppendix

C-1

APPENDIXC

GeneralInformationaboutSTAMP

“Forcenturiescomplexityhasbeenhandledbytraditionalmethodsbreakingthesystemintosmaller

components,examiningandanalysingeachcomponentinisolation,andthencombiningtheresults

inorder tounderstandthebehaviorof thecomposedcomponents. […]Thesuccessof this typeof

decompositional or reductionist approach relies on the assumption that the separation and

individual analysis does not distort the phenomenon or property of interest. […] Complexity is

creating“unknowns”thatcannotbeidentifiedbybreakingthesystembehaviorintochainsofevents.

Inaddition,complexityisleadingtoimportantsystemproperties(suchassafety)notbeingrelatedto

thebehaviorofindividualsystemcomponentsbutrathertotheinteractionsamongthecomponents.

Accidentscanoccurduetounsafeinteractionsamongcomponentsthathavenotfailedand,infact,

satisfy their requirements. […] STAMP (System-Theoretic Accident Model and Processes) is an

accident causalitymodelbasedon systems theory. […]Systems theorywasdevelopedafterWorld

War II to copewith the increasingly complex systemswith advanced technology that were being

created.[…]

Someuniqueaspectsofsystemstheoryare:

• Thesystemistreatedasawhole,notasthesumofitsparts.[…]

• A primary concern is emergent properties, which are properties that are not in the

summation of the individual components but “emerge” when the components interact.

Emergentpropertiescanonlybetreatedadequatelybytakingintoaccountalltheirtechnical

andsocialaspects.

• Emergentpropertiesarisefromrelationshipsamongthepartsofthesystem,thatis,byhow

theyinteractandfittogether.[…]

It expands the traditional model of causality beyond a chain of directly-related failure events or

component failures to include more complex processes and unsafe interactions among system

components, […].The twomostwidelyusedSTAMP-basedtools todayareSTPA (System-Theoretic

ProcessAnalysis)andCAST(CausalAnalysisbasedonSTAMP).STPAisapro-activeanalysismethod

thatanalysesthepotentialcauseofaccidentsduringdevelopmentsothathazardscanbeeliminated

or controlled. CAST is a retroactive analysismethod that examines an accident/ incident that has

occurredandidentifiesthecausalfactorsthatwereinvolved”(Leveson,STPAHandbook,2018,p.5,

7,4,10,12,13).

“CASTcanbeusedto identifythequestionsthatneedtobeansweredtofullyunderstandwhythe

accident occurred. It provides the basis formaximizing learning from the events. The use of CAST

TUGrazIMasterthesis

CAppendix

C-2

does not lead to identifying single causal factors or variables. Instead it provides the ability to

examine the entire sociotechnical system design to identify theweaknesses in the existing safety

controlstructureandtoidentifychangesthatwillnotsimplyeliminatesymptomsbutpotentiallyall

thecausalfactors,includingthesystemicones.OnegoalofCASTistogetawayfromassigningblame

andinsteadtoshiftthefocustowhytheaccidentoccurredandhowtopreventsimilarlossesinthe

future.Toaccomplishthisgoal, it isnecessarytominimizehindsightbiasand insteadtodetermine

why people behaved the way they did, given the information they had at the time” (Leveson,

EngineeringaSaferWorld,2011,p.349).

“STPAandSTAMPwerefoundtobemoreefficientandeffectivethantraditionalmethods,butthey

canbecombinedwithtraditionalmethods,too.[…]Theyhaveasolidtheoreticalbackgroundanda

practicalapplicabilitytocomplexproblems”(Koglbauer,2018,p.131-133).

HierarchicalControlStructure(HCS)inSTAMP

ReferringtoLevesson(2018),aHCScomprisesoverlappingandinteractingcontrolloops,whichhelp

tomanagethecomplexity.Thisisoneofthemaininvestigationsineveryhazardanalysis.Ingeneral,

a controller may provide control actions to control some process and enforce constraints on the

behavior of the controlled process. The control algorithms (also called operating procedures or

decision-making rules) determine the control actions to provide. Controllers have process models

(also called mental models) that represent the human controller’s internal beliefs used to make

decisions. Processmodelsmay include beliefs about the process being controlled or other relevant

aspects of the system or the environment, and theymay be updated in part by feedback used to

observethecontrolledprocess(rf.(Leveson,STPAHandbook,2018,p.22,23)).

Leveson(2011)describesthatapplyingtheCASTanalysismethodentailsunderstandingthedynamic

processthatledtotheloss.Theaccidentprocessisdocumentedbyshowingthesociotechnicalsafety

controlstructureforthesysteminvolvedandthesafetyconstraintsthatwereviolatedateachlevelof

thiscontrolstructure,aswellaswhy.Theanalysisresultsinmultipleviewsoftheaccident,depending

ontheperspectiveandlevelfromwhichthelossisbeingviewed.Movingupthelevelsofthesafety

control structure determines how and why each successive higher level in the control structure

allowedorcontributedtotheinadequatecontrolatthecurrentlevel(rf.(Leveson,EngineeringaSafer

World,2011,p.350,351)).

TUGrazIMasterthesis

DAppendix

D-1

APPENDIXDIn this appendix, the author collects and summarizes essential information and data from various

availabledocumentsaboutthebasiceventsoftheflightN4252G.Itsknowledgeandunderstandingis

relevantforthemodelingoftheaccidentbasedonSTAMP(Leveson,2011).

HistoryofFlightN4252G

“OnJune9,2016,about13:09centraldaylight time,aCirrusSR20single-engineairplane,N4252G,

wassubstantiallydamagedafteritimpactedterrainfollowingalossofcontrolduringinitialclimbat

theWilliam P. Hobby Airport (HOU), Houston, Texas” (NTSB, Cockpit Display(s) - Recorded Flight

Data, 2017, p. 1). “Witnesses saw the airplane at a low altitude when it turned to the left and

descended.A security camera video showed that the airplane spun to the left andwas about 45°

nosedowninaslightly left-wing-lowattitudebefore impactwithterrain.Theairplaneimpactedan

unoccupied automobile in a hardware store parking lot about half-mile north of runway 35. The

video showed that the airplane’s airframe parachute rocket motor activated during the impact;

however, the parachute remained stowed in the empennage and did not deploy” (NTSB, Aviation

AccidentFinalReport,2017,p.4).“Theprivatepilotandthetwopassengerswerefatallyinjured.The

airplanewasregisteredandoperated[…]undertheprovisionsof14CodeofFederalRegulationsPart

91asapersonalflight.Visualmeteorologicalconditionsprevailedandavisualflightrules(VFR)flight

planhadbeenfiled.TheairplanedepartedfromUniversityofOklahomaWestheimerAirport(OUN),

Norman,Oklahoma[…]andwasdestinedforHOU”(NTSB,CockpitDisplay(s)-RecordedFlightData,

2017,p.1).

TUGrazIMasterthesis

DAppendix

D-2

SummaryofBasicEventsofFlightN4252G

Factualaccident informationretrievedfromtheNTSBAviationAccidentFinalReport,2017andthe

HOUTowerAccidentPackageN4252G,2018arelistedasfollows:

Destination: HOU,Texas/USA

Dateandtime: June09,2016,13:09localtime(CDT)

Aircraft: CIRRUSDESIGNCORPSR20

Airframetotaltime21: 429hours,42hourssincelastinspection(January16,2016)

Avionics22: GarminG1000IntegratedFlightDeckwithRDM

Definingevent: Lossofcontrolinflight

Registration: N4252G

Serialnumber: 2217

Aircraftdamage: substantial

Personsonboard: 1pilot(female,age46),2passengers

Injuries: 3fatal

NTSBnumber: CEN16FA211

Positionofsun: Solarpositionatdate/timeofaccidentwasazimuth/elevation158°/83°

(rf.(NTSB,AviationAccidentFinalReport,2017,p.1-10),(HOU-ATCT-0064,2018,p.40)).

Thefollowingdatawereresearchedandsummarizedbytheauthor:

Runwaysinuse23: Runway4,LDA6000ftx150ft,4-LightPAPI(3.0°),thresholdelevation42ft

Runway35,LDA7602ftx150ft,4-LightPAPI(3.0°),thresholdelevation43ft

Weather24: At09:53CDT(approximatedeparturetime),visibility10miles,lowestclouds

werescatteredat2400ftAGL,brokenat18000ftAGL,winddirection070°

with8kts,temperature30°C,dewpoint23°C,AltimeterSetting29.95inches

Hg,noprecipitation;

At 12:53CDT (approximate accident time), visibility 10miles, lowest clouds

werebrokenat3600ftAGL,winddirection100°withspeeds/gusts12/16

21atthetimeofaccident22Electronicsystemsusedonaircraft.23Runwaydatawereretrievedfromhttps://www.airnav.com/airport/KHOUandverifiedwiththeHOUTowerAccident Package (HOU-ATCT-0064 2018, p. 40). Restrictions on LDA and serviceability of PAPI could not beverified,astheNTSBFinalReportandtheavailableNTSBDMSdocumentsoftheN4252GaccidentdonotstateNOTAMsandgeneralservicabilitiesatHOUatthetimeofaccident.24ObservedatHOUairport,1NMdistantfromaccidentsite.Source:WeatherSummaryFile(p.1)asretrievedfromNTSBDMSWebsite:https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB

TUGrazIMasterthesis

DAppendix

D-3

kts,temperature32°C,dewpoint22°C,AltimeterSetting29.94inchesHg,no

precipitation;

Availableweatherforecastsonthedayofaccidentarenotmentionedinthe

officialNTSBaccidentreportanditsaccompanyingdocuments.

Massandbalance25: Themassandbalanceenvelopewasrecalculatedbytheauthorforthetime

of takeoff and impact. The results showed that the center of gravity was

withinsafelimits26forthewholeprogressofflight.

Flightpreparation: TherewasnoinformationmentionedintheofficialNTSBaccidentreportand

its accompanying documents regarding details of the flight preparation

packagefromthepilot.

Remainingfuel27: leftwingtank:13US-gal,rightwingtank:8.8US-gal

(equalsaremainingendurance28ofapproximately2hours)

Max.glideratio29: 9:1(equals6.34°)withbestglidespeed

25Author’snote:Astheactualbasic-empty-massofN4252Gwasnotavailableintheprevailingdocuments,theauthorappliedthebasic-empty-mass/-momentdataofasimilarSR20aircraft(2144lbs/303561lbs-inch)fortherecalculation.Forpilotandpassengersthefollowingnumberswereused:femalepilotwith155lbs,twomalepassengerswith175lbseach(oneofthemoccupyingthefrontseat).Theamountofcarriedbaggagecouldnotbeconfirmed.Therefore,twocalculationswithandwithoutanassumedtotalbaggagemassof65lbswereconsidered.Fuelonboard(28US-galinboththeleftandrightwingtankfortakeoff;13US-galintheleftand8.8US-galintheright wing tank before the impact) was considered as retrieved from the stored onboard data record(Attachment1-CockpitDisplaysFactualReport.csv)fromNTSBDMSwebsite:https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB26FordetailsregardingsafeloadinglimitsrefertoPOH-SR20(2015),Section6,WeightandBalanceData.27Retrievedby theauthor fromthe laststoredonboarddatarecordbefore the impactat13:09:02CDT fromNTSBDMSwebsite:https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB28Recalculated by the authorwith POH-SR20 2015, Section5, Range Endurance Profile for 65% Power (FuelFlow10,5US-galperhour).29RetrievedbytheauthorfromPOH-SR20,2015,Section3,ChapterEmergencyDescent,p.3-14.

TUGrazIMasterthesis

DAppendix

D-4

Pilot-Information

This section lists factual pilot information retrieved from the NTSB Aviation Accident Final Report

(2017):

Pilot: Female,age46

PilotLicense: PrivatePilotCertificate (single engine land)was receivedonMay2,

2014,nootherratings30

Medicalcertification: Class3withoutwaivers/limitations,

lastFAAmedicalexamOctober10,2014

Pilothours: 332.6hours (Total, all aircraft), 303.6hours (Total, this make and

model), 253hours (Pilot In Command, all aircraft), 28hours (Last

90days,allaircraft),7hours(Last30days,allaircraft),0hours(Last

24hours,allaircraft)

Pilot’sairportexperience: According to the logbook, shehad landedwithin class-Bairspaceat

least four times. Her most recent flight in class-B airspace was to

DallasLoveField (DAL),Dallas,Texas,andconsistedofa landingon

May30,2016,andatakeoffonJune3,2016.Therewasnoevidence

thatshehadflowntoHOUbeforetheaccidentflight.

Flightreview: HerlastflightrevieworequivalentwasonMay2,2014.

Interviewswiththepilot’sflightinstructorsandreviewofherlogbook

didnot findevidence that thepilothadcompleteda flight review in

theprevious24calendarmonths,asrequiredby14CFR61.56(c).31

Pathologicalinformation: An autopsy on the pilot was performed. The cause of death was

multipleblunt force injuries, and themannerofdeathwas ruledan

accident. Forensic toxicology on specimens from the pilot detected

thefollowingsubstances:Ibuprofen,Naproxen,Zolpidem.

TheuseofIbuprofenandNaproxenwouldgenerallynotpresentahazardtoaviationsafety.Zolpidem

isaprescriptionmedicationused to treat insomniaandmay impairmentaland/orphysicalability

required for the performance of potentially hazardous tasks, such as driving, flying and operating

heavymachinery.Due toadverse sideeffects, theFAA recommendswaitingat least24hoursafter

useofZolpidembeforeflying(rf.(NTSB,AviationAccidentFinalReport,2017,p.5,8)). 30Ratingsinthiscontextmeansotheraircraftratings,instrumentratings(IFR)orinstructorratings.31Title 14 CFR part 61.56(c) states thata personmay not act as pilot-in-command of an aircraft unless thatpersonhasaccomplishedasatisfactoryflightreviewwithinthepreceding24calendarmonths.

TUGrazIMasterthesis

DAppendix

D-5

Pilot-ExperienceLevel

Theon-typeandgeneralexperienceoftheaccidentpilotgainedinarelativelyshorttimeofjustover

two years, as mentioned previously, provides the impression of a well-experienced pilot. For the

process of modeling the prevailing accident in STAMP (Leveson, 2011), the author decided to

determine the Pilot’s Capability Category in reference to the pilot’s experience according to the

Envelope of Safety provided by the aircraft manufacturer Cirrus in its FOM-SR20 (2011) and

summarized in L Appendix, Figure 6-2Guidance for establishing PersonalWeatherMinimums and

Figure6-3EnvelopeofSafety.Thegrading (total ratingpointsaddedup:27) for theaccidentpilot

wascalculatedbytheauthoranticipatingthefollowingfacts:2-5yearsactivelyflying(3points),last

training >24months (5points), private pilot certificate (4points), total time <500hours (5points),

exact number of hours logged in the last 12months not documented (therefore, anticipated as

4points), 28hours in Cirrus in the last 90days (3points), no pilot mishap (0points), and Cirrus

Landingsduringthe last30daysnotdocumented(therefore,anticipatedas3points).Therewasno

documentation found concerning whether the pilot had successfully completed a Cirrus Transition

Training(rf.(FOM-SR20,2011,p.2-6)).

ItconcludedtodefinethePilot’sCapabilityCategoryoftheaccidentpilotas“infrequentflyer”.

In respect of thedefinedPilot’s CapabilityCategory, the aircraftmanufacturerCirrus recommends

thefollowingPersonalWeatherMinimums(fordetails,refertoLAppendix,Figure6-2Guidancefor

establishingPersonalWeatherMinimums).

windlimit15kts,x-windlimit5kts,maximumgust5kts

TUGrazIMasterthesis

EAppendix

E-1

APPENDIXEIn this appendix, the author summarizes the most relevant aspects of the SR20 Pilot Operating

Handbook (POH) and the SR20 Flight Operations Manual (FOM) for modeling the accident with

STAMP(Leveson,2011).

RelevantAspects-SR20PilotOperatingHandbook(POH)

A1was theactual revisionnumber (revisedDecember29,2015)at the timeof theaccidentand it

wasstillunrevisedandvalidatthetimeofpublicationofthisthesis:

POH,Section2– Limitations describes that theaircraft is certified in thenormal categoryandnot

designed for aerobatic operations.Only those operations incidental to normal flight are approved.

Theseoperationsincludenormalstalls,chandelles,lazyeights,andturnsinwhichtheangleofbankis

limitedto60°.Aerobaticmaneuversandspinsareprohibited.

ThemaximumflapextendedspeedVfeisthehighestspeedpermissiblewithwingflapsextended,itis

limited to 119 KIAS for Flaps 50%, and 104 KIAS for Flaps 100%. Themaximum structural cruising

speedVnoisthespeedthatshouldnotbeexceededexceptinsmoothair,andthenonlywithcaution.

Thenever-exceedspeedVneof200KIASisthespeedlimitthatmaynotbeexceededatanytime.

The airspeed indications are marked as follows: WHITE-arc32 - 61-104 KIAS - Full Flap Operating

Range,GREEN-arc33 -69-163KIAS -NormalOperatingRange,YELLOW-arc34 -CautionRange-163-

200KIAS,REDline35-200KIAS-Never-exceedspeed(rf.(POH-SR20,2015,p.2-11,2-4,2-5)).

POH, Section 3 – Emergency Procedures warns that in all cases if the aircraft enters an unusual

attitude followingor inconnectionwithastall,aspinconditionshouldbeassumedand immediate

deploymentof theCAPS is required.Underno circumstances should spin recoveryother thanCAPS

deployment be attempted. The aircraft is not approved for spins and has not been certified for

traditional spin recovery characteristics. The only approved and demonstrated method of spin

recovery is the activation of the CAPS. Accordingly, if the aircraft enters a spin, CAPS must be

deployed immediately.While the stall characteristics of the aircraftmake inadvertent entry into a

32“[The] lower limit is the most adverse stall speed in the landing configuration. [The] upper limit is themaximumspeedpermissiblewithflapsextended”(POH-SR2029.12.2015,p.2-5). 33“[The] lower limit is themaximumweightstall speedatmost forwardCGwithflaps retracted. [The]upperlimitisthemaximumstructuralcruisingspeed”(POH-SR2029.12.2015,p.2-5). 34“Operationsmustbeconductedwithcautionandonlyinsmoothair”(POH-SR2029.12.2015,p.2-5). 35“Maximumspeedforalloperations”(POH-SR2029.12.2015,p.2-5).

TUGrazIMasterthesis

EAppendix

E-2

spinextremelyunlikely,it ispossible.Spinentrycanbeavoidedbyusinggoodairmanship,including

coordinateduseofcontrols in turns,properairspeedcontrol following the recommendationsof the

POH, and never abusing the flight controls with accelerated inputs when close to the stall. If the

controls are misapplied and abused aggressive inputs are made to the elevator, rudder and/ or

aileronsatthestall,anabruptwingdropmaybefeltandaspinmaybeentered.

The CAPS should also be used in other life-threatening emergencies where CAPS deployment is

determined to be safer than continued flight and landing. Several possible scenarios in which the

activation of the CAPS would be appropriate include mid-air collisions, structural failures, loss of

control,landingininhospitableterrainandpilotincapacitation(rf.(POH-SR20,2015,p.3-28,3-33,3-

34)).

POH,Section4–NormalProceduresadvisesthatnormallandingsaretobemadewithfullflapswith

poweronoroff.Thespeedsforlandingapproachareasfollows:NormalApproachFlaps-Up88KIAS,

NormalApproach-Flaps50%83KIAS,NormalApproach-Flaps100%78KIAS.TheGo-AroundSpeed

with Flaps 50% is 78 KIAS. Surface winds and air turbulence are usually the primary factors in

determiningthemostcomfortableapproachspeeds.

Crosswind landings are made with full flaps and prolonged slips to be avoided. The maximum

allowable crosswind velocity is dependent upon the pilot capability as well as aircraft limitations.

Operationindirectcrosswindsof20ktshasbeendemonstrated.

Theprocedures for balked landings (go-arounds) state to climb, disengage theautopilot, apply full

power,andthenreducetheflapsettingto50%.Ifobstaclesmustbeclearedduringthego-around,a

climbatthebestangleofclimbspeed(81-83KIAS)with50%flapshastobeachieved.Afterclearing

anyobstacles,theprocedurestatestoretracttheflapsandacceleratetothenormalflaps-upclimb

speed.

Aircraftstallcharacteristicsareconventional.Power-offstallsmaybeaccompaniedbyaslightnose

bobbingiffullaftstickisheld.Power-onstallsaremarkedbyahighsinkrateatfullaftstick.Power-

offstallspeedsatmaximumweightforbothforwardandaftCGpositionsareasfollows:forFlapsUP

(0%)–69KIASwithwingslevel(0°bank),forFlaps50%-63-66KIASwithwingslevel(0°bank),for

FlapsFULL(100%)-59-61KIASwithwings level(0°bank).Thealtitudelossforawings levelstall is

definedas250ftormore.KIASvaluesmaynotbeaccurateatstall.

Whenpracticingstallsataltitude,itisnotedthatastheairspeedisslowlyreduced,aslightairframe

buffetwillbenoticed,thestallspeedwarninghornisactivatedbetween5and10ktsbeforethestall,

andtheCrewAlertingSystemdisplaysaSTALLwarningannunciation.Normally,thestallismarkedby

agentlenosedropwhilethewingscaneasilybeheldlevelorinthebankwiththecoordinateduseof

TUGrazIMasterthesis

EAppendix

E-3

theaileronsandrudder.Uponstallwarninginflight,recoveryhastobeaccomplishedbyimmediately

reducingbackpressuretomaintainsafeairspeed,addingpower ifnecessaryandrollingwings level

withthecoordinateduseofthecontrols.

Awarningreferstoextremecaretobetakentoavoiduncoordinated,acceleratedorabusedcontrol

inputswhenclosetothestall,especiallywhenclosetotheground(rf.(POH-SR20,2015,p.4-21,4-3,

4-22,4-23.5-12)).

POH,Section7–AirplaneandSystemsDescriptiondescribesthevariousaircraftsystems:

AvionicsSystem-ThePerspectiveIntegratedAvionicsSystemprovidesadvancedcockpitfunctionality

and improved situational awareness through the use of fully-integrated flight, engine,

communication,navigationandmonitoringequipment.ThePrimaryFlightDisplay,locateddirectlyin

front of the pilot, is intended to be the primary display of flight parameter information (attitude,

airspeed,heading,andaltitude)duringnormaloperations.

FlightControls-Theairplaneusesconventionalflightcontrolsforailerons,elevatorandrudder.The

controlsurfacesarepilotcontrolledthrougheitheroftwosingle-handedsidecontrolyokesmounted

beneaththeinstrumentpanel.Thelocationanddesignofthecontrolyokesalloweasy,naturaluseby

thepilot.Thecontrolsystemusesacombinationofpushrods,cablesandbellcranksforcontrolofthe

surfaces.

Pitch trim is provided by adjusting the neutral position of the compression spring cartridge in the

elevator control system bymeans of an electricmotor. It is possible to easily override full trim or

autopilotinputsbyusingnormalcontrolinputs.

Rolltrimisprovidedbyadjustingtheneutralpositionofacompressionspringcartridgeintheaileron

control systembymeansofanelectricmotor.Theelectric roll trim isalsousedby theautopilot to

position the ailerons. It is possible to easily override full trim or autopilot inputs by using normal

controlinputs.

Yaw trim is provided by spring cartridge attached to the rudder pedal torque tube and console

structure. The spring cartridge provides a centring force regardless of the direction of rudder

deflection.Theyawtrimisground-adjustableonly.

Engine - The airplane is powered by a Teledyne Continental IO-360-ES, six-cylinder, normally

aspirated,fuel-injectedenginede-ratedto200horsepowerat2700RPM.

The single-lever throttle control on the console adjusts the engine throttle setting in addition to

automaticallyadjustingpropellerspeed.Theleverismechanicallylinkedbycablestotheairthrottle

body/fuel-meteringvalveandtothepropellergovernor.MovingthelevertowardsMAXopenstheair

throttle butterfly and meters more fuel to the fuel manifold. A separate cable to the propeller

TUGrazIMasterthesis

EAppendix

E-4

governoradjusts thegovernoroilpressure to increasepropellerpitch tomaintainengineRPM.The

system is set tomaintainapproximately2500RPMthroughout the cruisepower settingsand2700

RPMatfullpower.

Percent power is shown in the upper left corner of the synoptic ENGINE page as both a simulated

gageandadigital value.Thedigitalpercentpowervalue isdisplayed inwhitenumeralsbelowthe

gage.Thedisplayunitscalculatethepercentageofmaximumenginepowerproducedbytheengine

based on an algorithm employingmanifold pressure, indicated air speed, outside air temperature,

pressurealtitude,enginespeed,andfuelflow.

WingFlaps-Theelectrically-controlled,single-slottedflapsprovidelow-speedliftenhancement.The

flaps are selectively set to three positions: 0%, 50% (16°) and 100% (32°) by operating the FLAP

control switch. The FLAP control switch positions the flaps through a motorized linear actuator

mechanicallyconnectedtobothflapsbyatorquetube.Proximityswitches intheactuator limitflap

traveltotheselectedpositionandprovidepositionindication.Anairfoil-shapedFLAPScontrolswitch

islocatedatthebottomoftheverticalsectionofthecenterconsole.Thecontrolswitchismarkedand

hasdetentsatthreepositions:UP(0%),50%and100%.TheappropriateVfespeedismarkedatthe

flap50%and100%switchpositions.Settingtheswitchtothedesiredpositionwillcausetheflapsto

extend or retract to the appropriate setting. An indicator light at each control switch position

illuminateswhenthe flaps reach theselectedposition.TheUP (0%) light isgreenand the50%and

100%lightsareyellow.

StallWarningSystem -Theairplane isequippedwithanelectro-pneumaticstallwarningsystemto

provideaudiblewarningofanapproachtoaerodynamicstall.Thesystemcomprisesan inlet in the

leadingedgeoftherightwing,apressureswitchandassociatedplumbing.

Astheairplaneapproachesastall,thelowpressureontheuppersurfaceofthewingsmovesforward

aroundtheleadingedgeofthewings.Asthelow-pressureareapassesoverthestallwarninginlet,a

slightnegativepressureissensedbythepressureswitch.Thepressureswitchthenprovidesasignal

to cause thewarning horn to sound, the red STALLwarning crew-alerting-system annunciation to

illuminate,and,ifengaged,theautopilotsystemtodisconnect.

Thewarning soundsatapproximately5 ktsabove stallwith full flapsandpoweroff inwings level

flightandatslightlygreatermarginsinturningandacceleratedflight.

Thesystemoperateson28voltsofdirect-currentsuppliedthoughthe2-ampSTALLWARNINGcircuit

breaker.Astallwarningsystempre-flightcheckisexplainedinthePOH(rf.(POH-SR20,2015,p.7-8,

7-10,7-12,7-35,7-39,7-25,7-76)).

TUGrazIMasterthesis

EAppendix

E-5

POH,Section10–SafetyInformationCAPSdescribesthatCAPSisdesignedtolowertheaircraftand

itspassengerstothegroundintheeventofalife-threateningemergency.CAPSdeploymentislikely

to result indamage to theairframeandpossible injury toaircraftoccupants. Itsuse shouldnotbe

taken lightly. Instead, possible CAPS activation scenarios should bewell thought out andmentally

practicedbyeveryCirruspilot.PilotswhoregularlyconductCAPStrainingandthinkaboutusingCAPS

willoftenhaveahigherprobabilityofdeployingCAPSwhennecessary.Cirrusalsorecommendsthat

pilotsdiscussCAPSdeploymentscenarioswithinstructorsaswellasfellowpilotsthroughforumssuch

as the Cirrus Owners and Pilots Association. In the event of a spin or loss of aircraft control,

immediate CAPS activation is required. In other situations, CAPS activation is at the informed

discretionofthepilotincommand.CAPShasbeenactivatedbypilotsatspeedsinexcessof180KIAS

onmultipleoccasionswithsuccessfuloutcomes.WhilethebestspeedtoactivateCAPSisbelow133

KIAS,atimelyactivationismostimportantforloss-of-controlsituations.

Loss of controlmay result frommany situations, such as a control system failure (disconnected or

jammedcontrols),severewaketurbulence,severeturbulencecausingupset,severeairframeicingor

pilotdisorientationcausedbyvertigoorpanic.Iflossofcontroloccurs,theCAPSshouldbeactivated

immediately. The POH further warns that in the event of a spin, immediate CAPS activation is

mandatoryand thatunderno circumstances should thepilotattempt to recover froma spinother

thanbyCAPSactivation.

Regardingpilotincapacitation,whichmaybetheresultofanythingfromapilot’smedicalcondition

to a bird strike that injures the pilot, if the passengers are not trained to land the aircraft, CAPS

activation by the passengers is highly recommended. This scenario should be discussed with

passengerspriortoflightandallappropriatepassengersshouldbebriefedonCAPSoperationsothey

couldeffectivelydeployCAPSifrequired.

GeneralDeploymentInformationstatesthatnominimumaltitudefordeploymenthasbeenset.This

is because the actual altitude loss during a particular deployment depends upon the airplane’s

airspeed,altitudeandattitudeatdeploymentaswellasotherenvironmentalfactors.However,inall

cases, the chances of a successful deployment increase with altitude. In the event of a spin,

immediate CAPS activation is mandatory regardless of altitude. In other situations, the pilot in

command may elect to troubleshoot a mechanical problem or attempt to descend out of icing

conditions if altitude and flight conditions permit. As a data point, altitude loss from level flight

deploymentshasbeendemonstratedat less than400 ft.Deploymentat sucha lowaltitude leaves

littleornotimefortheaircraft tostabilizeunderthecanopyor for thecabintobesecured.A low-

altitude deployment increases the risk of injury or death and should be avoided. If circumstances

permit, it isadvisable toactivate theCAPSatorabove2000 ftAGL.AfteraCAPSdeployment, the

TUGrazIMasterthesis

EAppendix

E-6

airplanewilldescendatlessthan1700fpmwithalateralspeedequaltothevelocityofthesurface

wind.TheCAPSlandingtouchdownisequivalenttogroundimpactfromaheightofapproximately10

ft.While theairframe,seats,and landinggeararedesignedtoaccommodatethestress,occupants

must be prepared for the landing. The overriding consideration in all CAPS deployed landings is to

preparetheoccupantsforthetouchdowntoprotectthemfrominjuryasmuchaspossible

(rf.(POH-SR20,2015,p.10-4,10-5,10-6,10-7)).

RelevantAspects-SR20FlightOperationsManual(FOM)

ReissueAwastheactualrevisionnumber(revisedFebruary2011)atthetimeoftheaccidentandit

wasstillunrevisedandvalidatthetimeofpublicationofthisthesis:

FOM,Section1-IntroductiondescribesthatproceduresintheFOMarederivedfromproceduresin

the FAA-approved Airplane FlightManual (AFM). Cirrus Aircraft has attempted to ensure that the

data contained agreeswith the data in the AFM. If there is any disagreement, the Airplane Flight

Manualisthefinalauthority(rf.(FOM-SR20,2011,p.1-1)).

FOM,Section2-GeneralOperatingProceduresdescribesintheCurrencyRequirementssectionthat

it is recommendedthatallpilotsoperate inaccordancewiththepoliciesandproceduresprescribed

within the FOM. In no casedoes it relieve the PIC from the responsibility ofmaking safe decisions

regarding the operation of the aircraft. Regarding initial training, Cirrus pilots should satisfactorily

complete the Cirrus Transition Training Course, Advanced Transition Training Course, Avionics

Differences,AirframeandPowerPlantDifferences,or theCirrusStandardized InstructorPilot (CSIP)

CoursepriortoactingaspilotincommandofaCirrusaircraft.

In respectof recurrent training,Cirruspilotsshouldcomplete recurrent trainingataCirrusTraining

Center(CTC)orwithaCSIPundertheguidancefoundintheCirrusSyllabusSuite.Recurrenttraining

emphasizes aeronautical decision-making, risk management, and airmanship, which leads to

increased proficiency. The recurrent training program provides an opportunity to meet the

requirementsofabiennialflightrevieworinstrumentproficiencycheck.

Cirrus pilots should maintain VFR currency by completing each of the following items in a Cirrus

aircraft:CirrusTransitionTrainingcourse,threetakeoffsandthreelandingstoafullstopwithinthe

previous60days,and10hoursasthePICwithintheprevious60days.Cirruspilotsshouldflywitha

Training Center Instructor (TCI) or with a CSIP tomeet the flight currency requirement if currency

lapses.

TUGrazIMasterthesis

EAppendix

E-7

Regarding personal minimums and risk assessment, all Cirrus pilots should regularly assess their

personal risk factorsanduse them todeveloppersonalminimums forwind, ceilingandvisibility.A

matrix in the FOM is available to establish the risk category (Author’s note: refer to L Appendix).

Pilotsshouldre-evaluatetheirriskcategoryonaquarterlybasisoranytimethatamajormilestone

occurs. This category should be applied to the recommended personal minimums found in the

Envelope of Safety. Note that the “Envelope of Safety” Table describes recommended personal

minimums forwind, ceiling, and visibility based on the pilot’s risk category, time of day, and pilot

rating.TheseminimumsarefollowedbycompanypilotsatCirrusAircraft(rf.(FOM-SR20,2011,p.2-

2,2-3,2-8,2-4,2-5)).Regardingtakeoffandlandingwindproficiency,theFOMdescribesthataCirrus

pilot shouldnotattempt to takeoffor landwhenthewindspeedandcrosswindcomponentexceed

the individual's capabilities.Adecision shouldbemade topostpone the flight if theweather isnot

acceptable(rf.(FOM-SR20,2011,p.2-5,2-11)).

A sterile cabin should be observed during departure, arrival andabnormal/ emergency operations,

andduringsterilecabinoperationsalldistractionssuchassatelliteradio,non-flightrelatedactivities

and unnecessary communicationwith passengers should beminimized (rf. (FOM-SR20, 2011, p. 2-

19)).

FOM, Section 3 - Standard Operating Procedures describes the recommended procedures when

operatingaCirrusaircraft.CirruspilotsareencouragedtofollowtheproceduresoutlinedintheFOM,

use their best judgment, and adapt the procedures when handling non-standard situations. The

majorityofCirrusaircraftoperationsareconductedonasingle-pilotbasis.Theworkloadassociated

withflyingtheaircraft,configuringandmonitoringavionics,communicatingwithairtrafficcontrol,

anddecision-makingrequirespilotstoefficientlymanagealltaskswhilemaintainingpositiveaircraft

control at all times. The following SRM procedures have been adapted from cockpit procedures

commontodualpilottransportcategoryaircraft.Inordertoensurethehighestlevelsofsafety,itis

strongly recommended that these single-pilot operating procedures are incorporated into the

operationoftheaircraft:

Priorityof Tasks - Thenumberonepriorityof thepilot is tomaintainaircraft control. Pilots should

maintain a high level of vigilance during periods of high and lowworkload to ensure that aircraft

control isalwaysmaintained. Onceaircraft control isassured,pilots should setandverify that the

avionics are correctly configured for navigation. This includes creating andmodifying flight plans,

selectingpropernavigationsourcesand/ortuningnavigationfrequencies.Useoftheautopilotmay

assistthepilotwithaccomplishingthesetasks.Communicationisanimportanttaskintheaircraftbut

TUGrazIMasterthesis

EAppendix

E-8

itfollowsaircraftcontrolandnavigationasapriority.Thistaskincludessettingassignedfrequencies,

controllingcommunicationvolumeandrespondingtoATCinstructions.

Theuseofstandardoperatingprocedureswillallowforsingle-pilotoperationswithhigher levelsof

safety and efficiency. Following standard procedures during flight operations will develop habit

patterns through repetition that allow pilots to be most efficient while completing tasks and

configuringtheaircraftforvariousphasesofflight.

The use of all available resources during flight in single-pilot operations will allow pilots to make

betterandmoretimelydecisions.Manyresourcesareavailabletopilots,suchasATC,FlightWatchor

FlightServiceStations,on-boardweatherdisplays,on-boardchartdisplays,andevenpassengers.

When used properly, checklists enhance the safety of flight by confirming that the aircraft is

appropriatelyconfiguredfortheflightcondition.Atthesametime,checklistsexpeditethecompletion

ofproceduresthatarenecessarytotransitiontosubsequentphasesofflight.

Regarding to passenger flight briefing, the pilot should provide a safety briefing, referencing the

passengerbriefingcard, toallpassengerspriortoeachflight.Asaminimum,passengersshouldbe

briefedonthefollowingitems:CAPS,smoking,seatbelts,doors,emergencyexits/egresshammerand

the use of oxygen. The pilot should also discuss sterile cabin procedures and other information as

necessary(rf.(FOM-SR20,2011,p.3-1,3-2,3-3,3-21)).

Ago-aroundshouldbeexecutedany time thatanapproachdoesnotmeet thestabilizedapproach

criteria.Ago-aroundshouldbecompletedfrommemorysinceitisatime-criticalmaneuver.Thefirst

priority of executing a go-around is to stop the aircraft’s descent. It is necessary to smoothly and

promptlyapplyfullpower(increasepowerlevertothefullforwardposition,ensurefullpowerisused

anddonotstopatanydetentsalongpowerlevertravel)whilesimultaneouslylevelingthewingsand

pitchingtheaircrafttostopthedescent.Theflapsshouldberetractedto50%,butnotfullyretracted

atthispointinthego-aroundbecauseitmayleadtoexcessivealtitudeloss.

Regardingnormallandings,theFOMsaysthattheyshouldbemadewith100%flaps.Finalapproach

speeds should beadjusted to account for gusts exceeding10kts by addinghalf of the gust factor.

Referringto“crosswindlandings”,theyshouldbemadewith100%flaps(rf.(FOM-SR20,2011,p.3-

77,3-81)).

FOM,Section4,AbnormalandEmergencyProcedures-CAPSDeploymentdescribesthatemergency

situationsinanaircraftarealwaysstressfulandpilotsmayoverlookallavailableoptionsforsurviving

theemergency.PilotswhoregularlyconductCAPStrainingandthinkaboutusingCAPSwilloftenhave

a higher probability of deploying CAPSwhennecessary. PerformingCAPS training in a Cirrus flight

trainingdeviceorsimulatorishighlyrecommended.Itisalsorecommendedthatfrequentflying

TUGrazIMasterthesis

EAppendix

E-9

passengers complete CAPS training in a Cirrus simulator to develop the ability to properly activate

CAPS.Regarding“unusualattitudes”itisadvisedthattheyaremostlikelytobeencounteredbypilots

wholackinstrumentskills,VFRpilotswhohaveinadvertentlyenteredIMC,orpilotsexperiencingan

abnormallyhighworkload.Pilotswhohaveenteredanunusualattitudehavetemporarilylostaircraft

controlorfailedtomaintainaircraftcontrol.Atthemomentofrecognition,thepilotmustmakean

immediate decision regarding whether the aircraft can be recovered using traditional recovery

techniques such as amanual recovery, engaging the autopilot (if within limitations), or activating

CAPS. Immediateactionby thepilot is requiredto recover theaircraft regardlessofwhichrecovery

methodischosen.Itisimportanttonotethatpilotswhohavelostaircraftcontrolmaybedisoriented

beyond the pointwhere traditional, hand flown recovery techniques are effective. CAPS activation

maybethebestrecoveryoptionavailable.Preventingunusualattitudesisthebestcourseofaction.

Pilotsareencouragedtousetheautopilotduringperiodsofhighworkload,butshouldnotbecome

overly-dependentontheautopilotforaircraftcontrol(rf.(FOM-SR20,2011,p.4-2,4-40)).

TUGrazIMasterthesis

FAppendix

F-1

APPENDIXF

ResultsRaisedbytheNTSBFinalReport

This appendix describes the probable causes from the official Aviation Accident Final Report

publishedonDecember12,2017tobecomparedwiththefinalresultsofthisthesis:

• Thepilot’simpropergo-aroundprocedurethatdidnotensurethattheairplanewasatasafe

airspeed before raising the flaps, which resulted in an exceedance of the critical angle of

attackandanacceleratedaerodynamicstallandspinintoterrain.

• The initial local controller'sdecision to keep thepilot in the trafficpattern, and the second

local controller's issuance of an unnecessarily complex clearance during a critical phase of

flightcontributedtotheaccident.

• Thepilot’slackofassertivenesswasalsoacontributingfactor

(rf.(NTSB,AviationAccidentFinalReport,2017,p.2)).

In addition to the final report, fifteen documents36 related to the N4252G accident have been

publishedviatheDocketManagementSystem(DMS)ontheNTSBpublicwebsite37forunrestricted

download. For the purpose ofmodeling the prevailing accident with STAMP (Leveson, 2011), the

authorhasretrievedthesedocumentsandfurtheranalysedtheminmoredetail.

36AirTrafficControlFactualReport,HOUTowerAccidentPackage,OUNTowerAccidentPackage,HOUTowerOperatingProcedures,N4252GRadarTargetFile-HOUASRGoogleEarthKMLTargetFile,HoustonApproachControlRadarFile (Shelf Item),CockpitDisplays -Specialist’sFactualReport,Attachment1 -CockpitDisplaysFactualReport,PilotToxicology,StatementofPartyRepresentativestoNTSBInvestigation,WeatherSummary,WreckageDiagram(CourtesyofHoustonPD),CFIStatements,Photos,StallSpeeds37https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB

TUGrazIMasterthesis

GAppendix

G-1

APPENDIXG

ChainofEvents

TheNTSB,AirTrafficControl,GroupChairman'sFactualReport(2016)desribesthechainofeventsas

follows:

N4252Gdeparted fromUniversityofOklahomaWestheimerairportat10:09CDTen route toHOU.

The pilot contacted Houston Approach at 12:27:48, reporting that she had received automated

terminalinformationservice(ATIS)informationHotelforHOU38.Thecontrollerinstructedthepilotto

descend to 5000 ft andmaintainVFR39. The flight received routineVFRhandlingand subsequently

descendedto1800ft.

At12:38:40, thecontroller toldthepilot toexpecta leftbasetothetrafficpatternforrunway4at

HOU.Vectoringandtrafficadvisoriescontinued,andat12:51:38,thecontrolleradvisedthepilot,“...

you’refollowingaBoeing737about1:00o’clockand5miles-onafourmilefinalat2000,cautionfor

waketurbulence”.Thepilotreportedtheotheraircraftinsight.

At12:52:20,thecontrollerinstructedthepilottoflyheading095tofollowthetraffic,issuedanother

waketurbulenceadvisory,andtransferredcommunicationstoHOUtower.Thepilotacknowledged.

ThepilotcontactedtheHOUtowerLCpositionat12:52:47andreportedat1600ft.Thepositionwas

beingworkedbyatrainee(LCT)andaninstructor(LCI).Thetraineemissedthesourceofthecalland

thought itwasaSouthwestAirlines(SWA)flight.Herespondedas if theSWApilothadcalled,then

realizedthatithadactuallybeenthepilotofN4252G.Afterresolvingtheconfusion,theLCTcontroller

transmitted,“Cirrus4252GHobbytower,you’renumber2followinga737ona3milefinal,caution

wake turbulence, runway 4 cleared to land”. The pilot read back the instructions correctly. The

controllerthenaskedwheretheaircraftwouldbeparking,andthepilotresponded,“We’llbeparking

atMillionAir,4252G”.

At12:53:51,theLCIcontrollertransmitted,“Cirrus4252Gproceeddirecttothenumbers,you’regoing

tobeinsidea737interceptinga10milefinal”.Thepilotasked,“OK,you’dlikemetoproceeddirect

tothenumbers,4252G?”TheLCIcontrollerresponded,“November52G,whatdidapproachtellyou

38InformationHotelwasbroadcastedafter11:53CDT,andreportedHOUweatherconditionsaswindwith100degreesat8kts,visibilityof10miles,scatteredcloudsat3,500feet,andabrokenceilingat18000feet(TheauthorofthisthesisrecalculatedthewindcomponentsconsideringFigure6-4Windcomponentdiagramasfollows:100°/8ktsequals2ktstailwindand8ktscrosswindforrunway35(356°runwaytrack)versus4ktsheadwindand7ktscrosswindforrunway4(041°runwaytrack)).39“MaintainVFR” isan instruction issued topilots to remain in flight conditions suitable for visual flight rules(VFR).

TUGrazIMasterthesis

GAppendix

G-2

before?” The pilot answered, “Um, to left base runway 4 and follow the Boeing, 4252G”. The LCI

controlleragaininstructedthepilotto,“...proceeddirectthenumbersforrunway4,directtoHobby”.

At 12:54:24, the Hobby Final controller called the LC controllers to ask that they have the Cirrus

proceeddirecttothenumbers,andtheLCIcontrollerrespondedthatthepilothadbeendirectedtodo

so.

At 12:54:39, the LCT controller asked the pilot tomaintainmaximum forward speed and proceed

directtothenumbers,advisingherthattherewasa737on9milefinalfollowingtheCirrusthatwas

overtakingitby80kts.Thepilotrespondedthatshewouldproceeddirecttothenumbersandkeep

herspeedup.

At12:55:49,theLCTcontrollerbroadcaststoallaircraftthatHOUATISinformationIndiawascurrent,

altimeter29.94.ThepilotwasnotrequiredtoacknowledgetheupdatedATISannouncementanddid

notdoso.

At12:55:59,SWA235contactedHOU,reportingthattheywereon5milefinalforrunway4.TheLCT

controllerrespondedthattheywerenumber2followingaCirruson2milefinal,clearedthepilotto

land,andinstructedhimtoslowtofinalapproachspeed.

At12:56:19,theLCTcontrollerbroadcastsawindcheck,080degreesat13ktsgustingto18kt.

At 12:56:58, the LCI controller called N4252G, and the pilot responded. The LCI controller then

continued, “Yeah, I’ve got traffic behind you, just go-around and fly runway heading for now,

maintainVFR,andI’mgoingtoputyoubackonthedownwindforrunway35.Thewindsare090at

13gusts18[kt].Canyouacceptrunway35?”Thepilotresponded,“We’retoandlineupforrunway

35downwind”. The LCI controller then told thepilot to fly runwayheading for runway4 “for right

now”.Thepilotresponded,“We’ll flyrunwayheadingfor4,4252G”.TheLCIcontrollerthencleared

SWA235toland.

At12:57:34,theLCIcontrollertransmitted,“N52Gwhenablegoaheadandmakearightdownwind

nowforrunway35andthenwe’lljustgoaheadandkeepthatrightturn,runway35clearedtoland”.

The pilot read back, “OK, make a right downwind for runway 35?” The LCI controller continued,

“N52Gyesandjustkeeptherightturnallthewayaround,you’rejustgoingtorollrightintothebase

forrunway35,clearedtoland.I’vegotanother737on5milefinaltorunway4andyou’regoingto

beinfrontofhim”.Thepilotacknowledgedwith,“...turningaroundforrunway35”

At 12:58:10, the LCI controller said, “... just enter the downwind for runway 35,” and the pilot

acknowledged.

At12:58:16,theLCIcontrollertoldthepilotthathewouldcalltherightbaseturn.

At12:58:48,theLCTcontrollerprovidedatrafficadvisorytothepilotofN4252Gaboutanother737

inboundtorunway4,andthepilotreportedthe737insight.TheLCTcontrollerinstructedthepilotto

TUGrazIMasterthesis

GAppendix

G-3

makearightbasetofollow[passbehind]the737,andagainclearedthepilottolandonrunway35.

Thepilotreadback,“we’regoingtomakearightbasefollowingthem...forrunway35,N4252G”.

At12:59:20,theLCTcontrollertoldthepilotto“turnleftheading30degrees”.Thiswastoresolvea

perceivedconflictbetweenN52GandSWA235.Thepilotreadback,“turnleftheading30degrees”.

At12:59:30,theLCIcontrolleraskedthepilotifshe,“...wantedtofollowthe737torunway4?”The

pilotresponded,“Yes,thatwouldbegreat”.Thecontrollerthentoldhertofollowthe737torunway4

and cleared her to land. The pilot then asked, “Am I turning a right base now, 4252G?” The LCI

controller continued, “N52G roger, justmaneuver back for the straight-in, I don’t knowwhichway

you’regoingnow,so just turnbackaroundtorunway35”.Thepilot replied,“Turningto35, I’mso

sorryfortheconfusion,4252G”.TheLCIcontrollerresponded,“That’sOK,we’llgetit”.

At 13:00:13, the LCI controller asked the pilot which direction she was turning. She responded, “I

thought Iwasturningarightbasefor35,4252G”.TheLCIcontrollercontinued,“... that’sfine52G,

uh,justmakeituh,yousayyou’reinarightturn,keepittight,Ineedyoutomakeittight”.Thepilot

answered,“Keepingturntight,4252G”.

At13:00:31,thecontrollerprovidedatrafficalertto“0GA”abouttraffic1mileawayat900ft,which

wasN4252G. That pilot reported that hewas “looking,” and the LCI controller continued, “N52G I

needyoutouhthereyougo,straightintorunway35,clearedtoland”.Thepilotreadback,“Straight

in to runway 35 and I don’t believe I’m lined up for that”. The LCI controller acknowledged and

instructed the pilot to, “... turn to the right and climb and maintain 1600, right turn”. The pilot

acknowledged,and the LCI controller continued, “Yes,ma’am,headingabout040,”which thepilot

readbackcorrectly.

At13:01:16,theLCIcontrollertransmitted,“OK52G,let’sdothis.Canyoudoarightturnbacktojoin

the straight-in to 35? Could you do it like that?” The pilot replied, “Yes, right turn back to 35,

N4252G”.TheLCIcontrollerinstructedthepilottomakearightturn,“allthewayaroundtorunway

35,”andagainclearedthepilottoland.Thepilotacknowledged.

At thesametime, theHobbyFinalcontrollerwascalling the tower toofferaspace toputN4252G

behindanotheraircraft,N4JJ, inboundon the runway4 final. The LCI controllerdidnot respond to

thatcall.

At13:01:44,N4JJcontactedthetoweronavisualapproachtorunway4.TheLCIcontrollertoldthe

pilottoreducetominimumspeed,andadvisedthathewouldbenumber2fortheairportfollowinga

Cirruson1milefinalforrunway35.ThepilotofN4JJacknowledgedtheinformation.

At13:02:02,theLCIcontrollertransmitted,“Cirrus52G,OK,you’relookinggoodjustcontinuearight

turnforrunway35.Doyouseerunway35still?”Thepilotresponded,“Yes,35,4252Ghaveitinsight,

continuingmyrollaround”.TheLCIcontrollercontinued,“Yes,ma’am,yeahyou’regoodsoyoucan

TUGrazIMasterthesis

GAppendix

G-4

startyourdescenttorunway35there,anduhclearedto landon35”.Thepilotreplied,“Clearedto

landon35,52G, thankyouverymuch”.Thecontroller thenprovidedawindcheck,“...winds40are

100at15guststo20”.Thepilotresponded,“OK,thankyou,tryingto losealtitude4252G”.TheLCI

controllercontinued,“Noproblem,littlebitofwindofftheright”.

At13:03:01, theLCIcontrollertransmitted,“N52Gifyoudon’twantto land– ifthat’stoohigh,we

canputyoubackaroundthedownwind,don’t force it ifyoucan’t”.Thepilotanswered,“OK-we’ll

see, thank you,4252G”.At1303:25, the LCI controller toldher, “OK, I think you’re toohigh,Cirrus

52G, you might be too high”. The pilot replied, “OK - we’ll go-around then, N4252G”. The LCI

controllertoldthepilottomakerighttrafficforrunway35.Thepilotreplied,“Soundsperfect,right

trafficrunway35,4252G”.

At13:04:38,theLCIcontrollerclearedN4252Gtoland,stating,“...makerightdownwindtorunway

35,andyouareclearedtoland-therewillbenoothertrafficforrunway4sothisonewillbeeasy”.

The pilot read back, “Making right traffic for downwind for runway 35, 4252G”. The controller

continued, “N52Gaffirmative, and cleared to landon runway35 via the rightdownwindand right

base”.Thepilotthenreadback,“Thankyou–rightdownwind,rightbase,4252G”.

At13:06:00, theLCIcontroller issuedatrafficadvisorytothepilotofN4252G,stating,“... there’sa

737onshortfinalrunway4touchingdownrightinfrontofyousojustcautionwaketurbulenceright

thereatthatintersection”.Thepilotresponded,“OK,I’vegotthatinsight,N4252G”.

At 13:07:03, the LCI controller asked if the pilot of N4252G had runway 35 in sight. The pilot

answered that shedid, and the controller providedawind check41, “090at 13gust 18, runway35

again, cleared to land”. The pilot replied, “35 cleared to land trying to get [laugh] down again,

4252G”.

At13:07:49,apositionreliefbriefingoccurredontheLCpositionandanewcontrollertookover.

At13:08:21, the pilot reported, “... going around, third timewill be a charm”. The new controller

responded, “OK, Cirrus 52G, just go ahead and make the left turn now to enter the downwind,

midfielddownwindforrunway4,ifyoucanjustkeepitinanicetightlowpattern,I’mgoingtohave

traffic 4 miles behind you so I need you to just kind of keep it in tight if you could”. The pilot

responded, “OK, this time will be runway 4, turning left, 4252G”. The controller continued, “And

actuallyImightendupsequencingyoubehindthattraffic,he’son4milesaminute,umitisgonnabe

40TheauthorofthisthesisrecalculatedthewindcomponentsconsideringFigure6-4Windcomponentdiagramasfollows:100°/15ktssteady(gustsupto20kts)equals4kts(gustsupto5kts)tailwindand14kts(gustsupto19kts)crosswindforrunway35(356°runwaytrack).41TheauthorofthisthesisrecalculatedthewindcomponentsconsideringFigure6-4Windcomponentdiagramasfollows:090°/13ktssteady(gustsupto18kts)equals1kt(nogusts)tailwindand13kts(gustsupto18kts)crosswindforrunway35(356°runwaytrack).

TUGrazIMasterthesis

GAppendix

G-5

abittightwiththeonebehinditsowhenyougetonthedownwind,stayonthedownwindandadvise

mewhenyouhave that737 in sight.We’ll eitherdo4orwemight swingyouaround to35uhuh

ma’am,ma’amuhstraightenupstraightenup!”

There were no further contacts with the pilot. N4252G crashed northwest of the airport in a

commercial parking lot, and the tower supervisor reported the accident to emergency services (rf.

(NTSB,AirTrafficControl,GroupChairman'sFactualReport,CEN16FA211,2016,p.4,5,6,7)).

TUGrazIMasterthesis

HAppendix

H-1

APPENDIXH

InterviewswithATCControllersheldbyNTSB

ThisappendixsummarizesrelevantfactsofpersonalinterviewsheldbytheNTSBwithinvolvedATC

controllersasdescribedintheNTSB,AirTrafficControl,GroupChairman'sFactualReport(2016).For

thisthesis,nameshavebeenerasedandreplacedbytheshortformoftheirpositionsbytheauthor.

HOULCI(OJTI)-Controller

TheATCgroupinterviewedtheLCIonJune15,2016.

HebeganworkingfortheFAAinDecember2002atLongviewATCT(GGG).InFebruary2012,theLCI

transferredtoHOU.HewascertifiedonallpositionsatHOUbyDecember2012,andheldacurrent

FAAmedicalcertificate.

On the day of the accident, the LCIwasworking his regular assigned shift of 05:30 to 13:30 CDT,

assignedtoprovideon-the-jobtraining(OJT)toatrainee(LCT)ontheLCposition.Onascaleof1to5,

the LCI described the traffic during period before the accident as “around a 3”. There were no

personaloroperationalissuesaffectinghisperformance,andhedidnotfeelfatiguedduringtheshift.

Duringtheprecedingmonth,hehadworked“acouple”ofovertimeshifts,andtypicallyworkedone

midnightshifteveryweek.

TheLCIdidnotfeelthatheneededtointervenemuchduringthetrainingsessionuntilN4252Gwas

inbound.Hesaidthatnormallyaircraftaresequencedbyapproachcontrolandthetowerjustclears

them to land. If the spacingwere to diminish unacceptably, then hewould either send one of the

aircraftaroundorsendthembacktoapproachtobere-sequenced.Hestatedthatapproachnormally

givesa“goodfeed”totheairportanditisnotcommonforthetowertohavetopullsomeoneoffthe

approachorswitchthemtoadifferentrunway.Hedescribedtherelationshipbetweenthetowerand

approachcontrolasgood.

TheLCIrecalledfirstseeingN4252Ginboundfromthewestonamodifiedbasetorunway4.When

thepilotcheckedin,histraineethoughtthecallwasfromaSouthwestB737onfinal.Theycorrected

the confusion and cleared the pilot of N4252G to land on runway 4. The LCI asked the pilot if

approachhadissuedanyrestrictionsandthentoldhertoproceeddirecttotherunwaynumbers.He

sawN4252Gjointhefinalandthenslowdown.

HenoticedthespacingdecreasingbetweenN4252Gandthefollowing737,sohetoldN4252Gtogo-

around.Hemadethatdecisionduetothe“flow”inuseattheairportandtheknowledgethatrunway

35wasalsoavailableforlanding.Thiswasacommon“out”thathehadusedmanytimestoresolvea

spacingissueratherthansendingtheaircraftbacktoapproachforresequencing.Hestatedthatifthe

TUGrazIMasterthesis

HAppendix

H-2

approachcontrollercalledtotakeanaircraftbackforsequencing,hewouldnotquestionitandwould

sendtheaircraftbacktoapproach.

TheLCItoldthepilottoenterrightdownwindforrunway35.N4252Govershotthefinalandwasnot

properlylinedupforrunway35.Theovershootstartedtolooklikeaproblemwiththeaircraftonthe

runway4 final, so theLCT issueda30-degree left turn for traffic.Thepilotseemedconfusedabout

whattodo,sotheLCItookoverthefrequencyandbeganworkingLConhisown.AfterN4252Gwas

linedupforrunway35,theaircraftlookedhigh(“acouplehundredftabovetherunwayatmidfield”),

soheagaininstructedthepilottogo-aroundandentertherightdownwind.Headdedthattherewas

no further traffic on the runway4 final, so thenext try “shouldbe easy”.He subsequently cleared

N4252G to landon runway35. Theaircraft endedup toohighagain, and thepilot reportedgoing

around.

TheFLMhadbeenmonitoringthelocalfrequenciesandcoordinatingonthelandlines.

TheLCIdidnotrecallhearinganyspecificlandlinecoordinationbetweentheFLMandapproach,but

generallywhen LC became busy the FLMhandled the coordinationwith approach control. The LCI

knewthat theFLMwasawareofN4252G’smultiplego-arounds.TheFLMdidnot interveneatany

timeduringtheincidentanddidnotaskquestionsabouttheeventafterwards.

TheLCI’s shiftwasalmostover, soanother LCcontroller (LCC)hadcome toLC to completea relief

briefingandtakeovertheposition.TheLCCmovedtothemonitorpositionfortherequired2-minute

positionoverlapperiod.HesawN4252Gturnleftcrosswindoffrunway35andthen“nosetheaircraft

straight down”. Based on radar and visual observation, the LCI estimated that N4252G was

approximately500ftabovegroundjustbeforetheaccident.HesawtheFLMpickupthecrashphone,

butwasnotawarewhichemergencyservicesrespondedtothescene.TheLCCcontinuedworkingthe

LCposition,butdeparturesatHOUwerestoppedduetotheaccident.

While he was dealing with the spacing issue between N4252G and the trailing SWA flight, the

approachcontrollercalledandtheLCIrepliedthathewouldtakecareof[thespacing].Hestatedthat

spacingissuesrequiringago-aroundorarunwaychangeonlyoccurredaboutonceaweek.

Afacilitybriefingitemprovidedtothegroupstatedthatitwasa“bestpractice”tohandlego-arounds

by transferring them back to the approach control for resequencing, while the I90/ HOU letter of

agreement stated that go-arounds should be handled as a satellite airport departure42 that is

transferredbacktoI90.Askedaboutthedisagreement,theLCIsaidthatkeepinggo-aroundaircraftin

the pattern was frequently coordinated with I90 and was a very standard alternate plan. It was

42Title 14 CFR part 91.129(c)(2)(ii) states that departing flight from a satelliteairportwithout an operatingcontrol tower must establish and maintain two-way radio communications with theATCfacility havingjurisdictionovertheClassDairspaceareaassoonaspracticableafterdeparting.

TUGrazIMasterthesis

HAppendix

H-3

common for FLMs to coordinatewith I90onbehalf of LC,but thatwouldnotnecessarily lead toa

conversationbetweenLCandtheFLMaboutwhathadbeendiscussed.

IntheLCI’sexperience,havinganaircraftmisstherunwaytwicewasunusual,andthiswasthefirst

timethathehadseensuchanoccurrence.AstheaircraftwasVFR,keepingitinthepatternwasthe

“normal”response.

TherewereaboutfivedevelopmentalsatHOU,andtheyweregenerallywellpreparedforOJTafter

completingtheirclassroomtraining.TheLCIsaidthathewouldnothavedoneanythingdifferentlyin

thissituation,andthatifalocalassistpositionhadbeenopenitwouldnothavechangedanything.

Overall,theLCIfeltthatHOUdoesaverygoodjobandusesgoodprocedures,butnotedthatthere

wasalwaysroomforimprovement.

TheLCIhadbeenonadministrativeleaveuntilWednesday,June15,2016,andhadnotparticipatedin

any discussionswith facilitymanagement about the accident. He has not participated in any crew

briefingssincehecametoHOU,andsaidtherewasnopracticeofdiscussingincidentsandaccidents

aslearningexperiences.Hewasnotawareofthespecificmembershipofthefacilitysafetycouncil(rf.

(NTSB,AirTrafficControl,GroupChairman'sFactualReport,CEN16FA211,2016,p.20,21,22)).

HOUFLM-Controller

TheATCgroupinterviewedtheFLMonJune15,2016.

He began working for the FAA in February 1991 at the FAA Academy, and was first assigned to

Burbank ATCT. He later transferred to Chicago Center, Rockford ATCT, ChicagoMidway ATCT, Las

VegasATCT,DaytonATCT, andDallas FortWorth InternationalATCTbefore coming toHOUas an

FLMinJune2015.HewascertifiedonallpositionsatHOUandheldacurrentmedicalcertificate.He

typicallyworked12to16hoursamonthontheLCandgroundcontrol(GC)positions,andotherwise

spentalmost40hoursaweekinthecabsupervisingtheoperation.

Onthedateoftheaccident,theFLMwasworkinghisregularassignedshiftof06:30to14:30CDTand

performinghisregularFLMduties.Thedaystartedwithsevencontrollers,includingonetrainee,but

around noon hewas notified that one of the controllers assigned to the shift had beenmedically

disqualified.Anothercontrollerhadalreadybeenapprovedforannual leave,soonlyfivecontrollers

wereavailable.Therewerenounusualequipment issuesaffectingtheoperation.Thewindsstarted

outvariablefrom050to110degrees,andincreasedinstrengthasthedaywenton.Therewereno

reports of wind shear or other wind issues during the shift. The FLMwas unsure where the wind

sensorwaslocatedontheairport,butnotedthattherewassoontobeachangeinthesystem.

Intheperiodleadinguptotheaccident,HOUwaslandingrunways4/35,anddepartingrunways4,

12L/R,and35.Mostofthetrafficwaslandingonrunway4anddepartingfromrunway12R.There

TUGrazIMasterthesis

HAppendix

H-4

wastraininginprogressontheLCposition,whichhewasmonitoringtothemaximumextentpossible

alongwithhisotherdutiesatthesupervisorypositioninthebackofthecab.

TheFLMfirstbecameawareofN4252Gwhenhesawtheaircraftonradaronaleftbaseforrunway

4,withotherjettrafficinboundonfinal.ThetrainingteamonLCdecidedtoturnN4252Gdirecttothe

runway.At thesametime,heheardapproachcallandask the tower to turnN4252Gdirect to the

runway.When the LCT controller issued the instruction,N4252Gmade a slow turn and proceeded

directlytotheendofrunway4.

TheFLMnoticedthattheB737trafficbehindN4252Gwasslowingbutstillovertakingtheaircraft.LC

toldthepilotofN4252Gtogo-aroundandflyrunwayheading.N4252Goverflewabout3⁄4ofrunway

4 before LC instructed the pilot to enter right downwind for runway 35. After N4252G turned

downwind,itstarteddriftingtowardstheothertrafficonfinalforrunway4.TheFLMheardtheLCT

controllertellN4252Gtoturnleft20degrees43,andthentheLCIcontrollertookovertheposition.

TheLCItoldthepilotofN4252Gtomakeagradual270degreeturnaroundtorunway35.Theplan

wastoputtheCirrusonrunway35throughagapbetweentherunway4arrivals.TheCirruswasnot

descendingverymuch.TheLCIthentoldthepilotthattheaircraftlookedtoohighandtogo-around.

TheLCIthensequencedN4252Gontoanotherdownwindforrunway35andclearedthepilottoland.

WhileN4252Gwas on downwind to runway35 for the second time, the FLM called approachand

askedthemtoslowtheirnextarrivaldowntobuildinalittlemorespacefortheCirrus.Theapproach

controllertoldtheFLMthathewouldtakeN4252Gback,buttheFLMsawthatN4252Gwasalready

turning base, so he told approach that the tower would just work the aircraft. The FLM did not

coordinate with LC about the call. Although the spacing between the runway 4 arrivals looked

adequate,theFLMsawN4252Gcominginhighonfinalagain(aroundtheheightofthetower),and

thepilotreportedthattheyweregoingaround.

TheLCI’sshiftwasending,sotheFLMhadtheLCTmovetoGCandsendacontroller(LCC)fromGCto

LCtorelievetheLCI.Afterthereliefbriefingwascompleted,theFLMheardtheLCCcalmlytalkingto

thepilot,whobythenwasontheupwindfollowingthego-around.TheFLMwasonthephone,sohe

didnothearexactlywhatwas said,althoughboth the controllerandpilot soundedcalm.TheFLM

then heard LCC saying “straighten it out, straighten it out!” and realized that there had been an

accident.Heputtheregularphonedownandactivatedthecrashphone,reportingthatthecrashwas

abouthalfamileupAirfieldRoad.Emergencyvehiclesresponded.

43Author’snote:TheofficialNTSBreportandATCtranscriptdescribes30degrees,thereforeitisconsideredtobeanambiguityerror.

TUGrazIMasterthesis

HAppendix

H-5

TheFLMalso told the flightdata/ clearancedelivery controller to call theother controllerup from

lunchimmediately.Theairtrafficmanagercameuptothecabtoassistwithemergencynotifications.

TheFLMgottheLCCofftheLCpositionaboutfiveminutesaftertheaccident.Hewasunabletoget

theothercontrollersoffposition forabout15minutesdue tostaffing.TheFLMspent thenext two

hoursupinthetowercab.

Hedidnotdiscusstheeventsoftheaccidentwiththecontrollersinvolved.Hewasmostlyconcerned

for the controller’s well-being and did not want to talk to about the accident with them. The

controllersweregivensomeadministrativeleaveinadditiontotheirregulardaysofftodecompress

andparticipateinstresscounseling.TheFLMcontactedthemovertheweekendtoensurethatthey

werecopingaftertheaccident.

WhenaskedabouttheLCC’sinstructiontoN4252Gto“keepturnintight”,theFLMsaidthatitwas

notstandardphraseology.

TheFLMsaid that the speedsof theaircraft coming inon finalarea “hit ormiss”. Sometimes the

aircraft come in fast and other times slower. HOU does not normally put restrictions on the final

unlessunusualconditionsat theairportareaffectingrunwayoccupancytimesorotheroperational

issues.Onoccasions,HOUhastobreakanaircraftoutonfinal,butitwasnotasystemicissue.Ifan

aircraftgoesaround,therearetwochoices:toeithergobacktoapproachorcomeintorunway35.

About90percentofthetimeifasmallVFRaircrafthadtobere-sequencedoffrunway4,thetower

wouldkeep theaircraftandnothand itoff toapproach.Thiswasnormalhandling followingago-

around.TheFLMsaidthathedidnotgiveanyinstructionstoLCbecausetheyhadthesituationunder

control. As far as the FLM could tell, both approaches to runway 35 were good and should have

worked:theaircraftsimplydidnotdescend.Thefirstapproachtorunway4wouldnothaveworked

andsendingN4252Garoundwasthebestoption.IftheyhadnotpulledN4252Gout,theywouldhave

potentiallyhadtosendtwootheraircraftaround.

TheFLMhastriedtogetcrewbriefingstogethersincehegottoHOU,butstaffinghasbeenshortand

briefingshavebeendifficult toaccommodate.He tries tomeetwithhiscrewwhenhecan,but the

priorityistheoperationovercrewbriefs.TheFLMorganisedtwoall-handsbriefingsscheduledforthe

following week. The supervisors and training specialist were to cover the operation so all the

controllerscouldmeetwiththeATMandthefacilityNATCArepresentative.

TheFLMhadnotcompletedmanyPerformanceRecordsofConference(PRCs)todocumentcontroller

performance,andadmitted that itwasanerroronhispart.With the recentevents that theyhave

had, PRCs have become more common. The FLM stated that he has undertaken performance

management fromdayonebuthis documentationwaspoor. The FLM said that thenewATMhas

addressed performance management with the FLMs and has stressed documentation within the

TUGrazIMasterthesis

HAppendix

H-6

allowabletimeconstraints.Hesaidthatitwasdifficultdocumentingthisduetohisworkloadwiththe

schedule. He attended FLM training at the end of 2015, which helped him to better understand

performancemanagement.HehadnotcompletedanyPRCsrelatedtothisaccidentasofthedateof

thisinterview.HewillbediscussingtheaccidentandATCcommunicationswiththeATMtoseehow

he wants to handle it. The FLM reported receiving no specific personal training on performance

managementorquality control in thepastmonth,althoughhe received some trainingon resource

management.

TheFLMcouldnotexplainwhyHOUhadtheirrecentissues,buthasfoundthatsomepeoplewerenot

engaged like they should have been. Some controllers have never seen certain situations and that

openedupopportunitiestocoachthem.Ifhehadtograde44thefacilitymanagementeffortstobrief

employeesabout issuesandevents,hewouldgivethema“CtoCminus”.Hefelt that thevalueof

theseexperiencesarenottaughtsufficientlywell.Hehasnotbeen involved intheAirTrafficSafety

ActionProgram (ATSAP45) event reviewand skill enhancement trainingprocess yetasa supervisor,

andhedidnotfileanATSAPreportforthisaccident.Hewasunsurewhetheranyofthecontrollersdid

so.The local safety councilhadnotbeenveryactiveprior toa recentvisit from thecentral service

area Quality Control Group.While their activity level had recently increased, he had still not seen

muchinformationcomingoutofthegroup.

If the FLM had the opportunity to do anything at HOU, he would improve the communication

throughouttheentirefacility.Controllersmaybebriefedaboutanoccurrence,butthereistoolittle

timeavailabletoensurethatunderstandingandlearningoccurs.Whenhetalkstohiscrew,ifthereis

aspecifictopictoaddress,allsevenofhiscontrollersreceivethesamebriefing.Ifitisaweekduring

whichamoregenericdiscussionispossible,hehassessionsthataremoreofacoachingnature.

Management staffing at HOU was one ATM, three supervisors, and one training specialist. The

activitylevelplacedthefacilityrightinthemiddleoftheATC8levels.

Thetowerwasnotprimarilyusingrunway12forarrivalsbecausethewindhadnotpickedupuntil

theafternoonarrivalpushwasinprogress,anditwasnotagoodtimetochangerunways.Landing

onthe12swhilealsolandingonrunway4wasdifficultduetotheairportlayout.

Theapproachcontrolwasusuallycooperativeaboutrestrictionsrequestedbythetower.

44Author’snote:commongradesinUSschoolsarescalingfromA(excellent)viaB(good),C(average),D(belowaverage)toE(insufficient).45Author’snote:FAAmodeledATSAPasavoluntarysafetyreportingprogramthathelpstoresolvesafetyissuesthatotherwisemightnothavebeenidentifiedorresolved.Nopunitiveordisciplinaryactionswillbetakenasaresult, provided those errors are not the result of gross negligence or illegal activity (rf. (retrieved fromhttps://www.natca.org/index.php/insider-articles/2183-atsap-what-you-need-to-know)).

TUGrazIMasterthesis

HAppendix

H-7

When asked if he had ever participated in a System Service Review process, the FLM said he had

temporarilyfilledaslotonthelocalsafetycouncil foranevent involvingarunwaycrossingwithout

usingvisualaids.Thewholeprocesstook60to90minutes.Healsoparticipatedinthelasthalfofthe

“servicesrenderedteleconference”forthisevent.

WhenaskedaboutthedecisiontoputtheCirrusonrunway35withtheexistingcrosswind,FLMsaid

thatthetowerhadbeenusingrunway35alldayforavarietyofaircraftwithnoissues.Hethought

that the controllers were making good decisions and the sequencing with the runway 4 arrivals

lookedgoodbothtimes.Heneverfeltaneedtointervene.Theproblemseemedtobethatthepilot

never descended sufficiently to reach the runway (rf. (NTSB, Air Traffic Control, Group Chairman's

FactualReport,CEN16FA211,2016,p.22,23,24,25)).

HOULC-Controller

TheATCgroupinterviewedtheLCcontroller(hereincalledLCC)onJune16,2016.

TheLCCbeganworking for theFAA inNovember1988at theFAAAcademy.Heworkedat various

facilitiesincludingSantaMariaATCT,SanJoseATCT,andHOUsincethen,arrivingatHOUin1998.He

alsoworkedseventemporarydetailsatOshkoshATCTduringtheannualEAAevent.Hewascertified

onallpositionsatHOU.HeheldacurrentATCmedicalcertificate.

Onthedateoftheaccident,theLCCwasworkinghisregularly-assignedshiftof05:30to15:30CDT.

Therewerenounusualpersonalorequipmentissuesaffectinghisperformance.

TheLCCwasworkingGCwhenhebecameawareofN4252GinboundtoHOU.Herecalledseeingthe

aircraft on radar about five miles out and again on short final to runway 4. He did not observe

anythingunusualuptothatpoint.HeheardoneoftheLCcontrollerssendN4252Garound,butwas

unsurewhether itwas thedevelopmental (LCT)or the trainer (LCI)who issued the instructions.He

thenheardthelocalcontrolcontrollersequenceN4252Gtorunway35.Hewasgenerallyawarethat

theCirruswasinthepattern,butwasmainlyoccupiedwithhisGCduties.TheLCCwasrelievedfrom

GC by the developmental controller who had been training on LC. He observed N4252G high and

southofrunway35.WhentheLCCwenttoLCtorelievetheLCI,henoticedN4252Govertherunway

andstillhigh.Hecouldnotreallyestimatethealtitudeoftheaircraft,butitjustseemedhigh.Hewas

hoping that the pilot was not going to try to land because the aircraft was at leastmidfield and

lookedlikeitwasgoingtotouchdownatthefarendoftherunway.

TheLCCheardthepilotofN4252Greportthatshewasgoingaround.Shecommented:“thirdtime’sa

charm”.Hefeltconfidentthatshewascomfortablebasedonthatcomment.TheLCCtoldthepilotto

makea“close-inpattern”torunway4andthentoldherthathemighthavetoamendthatorperhaps

taketheaircrafttorunway35basedonothertraffic.

TUGrazIMasterthesis

HAppendix

H-8

The LCC then saw the aircraft “winging ... over” and “going steep”. He estimated N4252G was

probablyclosetoa90-degreebankbeforetheaircraftstartedto fall.Hetransmitted“Straighten it

out,straightenitout,”wantingthepilottolevelthewings,althoughtheairplanecrashed.Afterthe

accident,theLCCrecalledsomeonecallingonthefrequencyaskingaboutdeparture.TheLCCadvised

theFLMofwhathadhappenedwithN4252Gbutdidnotrecallthespecificsoftheconversation.

When asked about the “low and tight” instruction that he gave the pilot, he said he had given

instructions like that tootherpilotsbutdidnot recall the specifics.Hisplanwas tohave theCirrus

followa737ontherunway4final,soheaskedthepilottoreportthe737 insightandthenadded

thathemighthavetoputtheCirrusbackonrunway35.

TheLCCsaidapproachdoesaprettygoodjobonfinalandtheydon’t“jamthemuptoooften”. Ifa

generalaviationaircraftwentaround,hewouldprobablykeeptheaircraftratherthangiveitbackto

approach,anddependingontrafficwouldtaketheaircrafttorunway4orrunway35.Theflowinthis

case was to runways 4 and 35, so that was where he would have kept the Cirrus even with the

existingcrosswind.Theaircraftlookedhighduringbothapproachestorunway35.

TheFLMishissupervisor.TheLCCstatedthathehasnotbeentomanycrewbriefingsinthepastfew

years,andtheywerenotregularevents.Hedidrecallreceivingsometrainingonincidentsoccurring

atotherfacilities,butnotthespecificcontent(rf.(NTSB,AirTrafficControl,GroupChairman'sFactual

Report,CEN16FA211,2016,p.25,26)).

HOULCT-Controller

TheATCgroupinterviewedtheLCTonJune17,2016.

He began working for the FAA in December 2010 at the FAA Academy. After completing initial

training, he reported toDavidWayneHooks airport (DWH) inMarch 2010. The LCT transferred to

HOUinJanuary2016.HewasqualifiedontheFD/CDandGCpositions,andwastrainingontheLC,

helicopter,and localassistpositions.TheLCThasreceivedapproximately19hoursofOJTontheLC

position. He held an ATCmedical certificate. He had Saturday and Sunday off. On the day of the

accident,hewasworkinghisregularly-assignedshiftof07:00to15:00CDTandreceivingtrainingon

theLCpositionfromhissecondaryOJTI,hereincalledtheLCI.Hewasunsurehowlonghehadbeenon

positionbeforetheaccident.

TheLCTfirstbecameawareofN4252Gwhentheaircraftwaseightmileswestoftheairport.When

thepilotcalled,hewastalkingtohisinstructorandmissedthecallsign.Hethoughtthetransmission

wasfromaninboundSouthwestflight,soheclearedtheSouthwestjettolandbeforerealizingthat

N4252Ghadcheckedin.HethenclearedthepilotofN4252Gtoland.HenoticedthattheSouthwest

flight was overtaking N4252Gwhen the SWA flight was on approximately a 9mile final. The LCT

TUGrazIMasterthesis

HAppendix

H-9

instructedN4252G to flydirectly to thenumbersandkeep their speedup. Theapproach controller

calledataboutthesametimeandaskedthetowertohaveN4252Gflydirectlytotheairport.TheLCT

statedthataircraftspeedsonfinalcouldbeadjustedwithoutcoordinationwiththeI90Hobbyfinal

controller.HestatedthatN4252GandthefollowingSWAjetwereadvisedoftheovertakesituation.

TheLCTandhisOJTI (LCI)hadbeendiscussingwhether the spacingbetween the jetand theCirrus

wouldwork.WhenN4252Gwasbetweenoneandtwomilesfromrunway4,theOJTItookoverthe

frequency and instructed the pilot to go-around. Hewas unsurewhy the OJTI had taken over the

frequency insteadof simplyhavinghim issue the clearance.TheOJTI told thepilot toentera right

downwindforrunway35.TheLCTthentookthefrequencyback.HenoticedthatN4252Ghadgone

pasttherunway35finalandwasapproachingtherunway4final.Heinstructedthepilottoturnleft

heading030 tostayaway fromtraffic landingon runway4.Theheadingwasbasedonboth radar

andvisualobservationoftheaircraft’strack.

TheOJTItookthefrequencybackandissuedinstructionstothepilotinanattempttogettheaircraft

linedupwithrunway35.TheLCTstatedthattheOJTIadvisedN4252Gthattheyappearedtobetoo

highand issuedgo-around instructions.Onthenextapproachtorunway35,theaircraftwasagain

toohighandthepilotinitiatedago-around.Theaircraftappearedtobeaboutthesamealtitudeon

bothapproachestorunway35,anddefinitelytoohightoland.

TheFLMtoldtheLCTtorelievethegroundcontroller,sohemovedtotheGCposition,andtheLCC

tookover theLCposition.HeheardtheLCCsequenceN4252Gtorunway4.Hisattentionwasthen

divertedbyGCduties.HedidnotobserveN4252Gturn leftcrosswind,butsawtheaircraftwhen it

wasbetween50and75ftabovetheground.

TheFLMactivatedthecrashphone.Departureswerestoppedduetotheaccident,althougharrivals

continued to land. One of the airport fire trucks requested control of the discrete emergency

frequency.

TheLCTwasrelieved fromthegroundcontrolpositionabout15minutesafter theaccident.Aftera

ten-minutebreak,hereturnedtothetowertoworkgroundcontrol.

The LCT stated that he had not had any discussionswith anyone following the event. He had not

spokentotheeventcrisisteambutplannedtodoso.

OJTdebriefstookplaceaftereachtrainingsessionifwarranted,andwerenormallycompletedbythe

endofeachday.

The LCT stated the new procedural changes being implemented by the facility are good, such as

requiringadherencetostandardproceduresandminimizingrunwaychanges.

TheLCThadnotseenverymanygo-aroundsintraining.Theusualprocedurewasforjetstoproceed

straight down the runway, then turn to heading 160,maintain 3000 ft, and contact departure. In

TUGrazIMasterthesis

HAppendix

H-10

classroominstruction,controllersaretaughttotreatgo-aroundsasasatelliteairportdeparture.He

had not yet received any simulator training, although a simulator is available at Houston

Intercontinental. He noted that simulator training was not provided for the LC position, but was

providedaspartofGCtraining.Radartrainingwasprovidedviaonlinelearningmodules.

Based on his experience at DWH, the LCT was asked how he would characterize the handling of

N4252G’s arrival. Having the Cirrusmixed in with the jetsmeant that the situation needed to be

watched, but itwas not amajor issue. The pilot never sounded flustered or disoriented. After the

accident,theairportfirecrewsaskedtousefrequency120.2andrespondedtothefarNWcornerof

theairport.

TheLCTwasuncertainabout the typeof separationbeingappliedbetweentheSWAflightand the

Cirrusonfinal.Herealizedthatitwasnotgoingtoworkwhenhistrainertookovertheposition.The

intentwastopreventaflyoverontherunway(rf.(NTSB,AirTrafficControl,GroupChairman'sFactual

Report,CEN16FA211,2016,p.27,28)).

I90-ApproachController

TheATCgroupinterviewedtheI90–ApproachControllerviatelephoneonJune17,2016.

TheI90–ApproachControllerbeganworkingfortheFAAinOctober1989.HisfirstfacilitywasSan

Juancenter/approachcontrolinPuertoRico.BeforebeingassignedtoI90in2008,heworkedatIsla

GrandeATCT,SanJuanATCT,andSanJuanCenter.HeheldanATCmedicalcertificate.

Onthedateoftheaccident,hewasworkinghisregularly-assignedshiftof07:00to15:00CDT.

TheI90–ApproachControllerhadbeenworkingtheHobbyFinalpositionforabout45minuteswhen

he first became aware of N4252G. He recalled taking a handoff from the “Lakeside” sector when

N4252Gwasapproximately20mileswestofHOU.N4252Gcameinonabaselegtorunway4.The

aircraft’sgroundspeedwasabout130ktswithaheadwind.ThepilotofN4252Gsoundedconfident.

SomeofthearrivalsintoHOUwerebeingvectoredaroundheavyweathersouth-westoftheairport.

HesequencedN4252GbehindaBoeing737andgavethepilotawaketurbulenceadvisory.Atthat

point,thepilotseemedfine.TheI90–ApproachControllerhadothertrafficbehindN4252Gonfinal,

soheissuedtheaircraftaheadingtoshortentheapproachandswitchedtheaircrafttoHOUtower.

HeadvisedtheaircraftsequencedbehindN4252Gtoreducespeedto150ktsorlessandswitchedthe

aircrafttoHOUtower.AfterbothaircraftwereonHOUtowerfrequency,thespacingappearedtobe

diminishingbetweenN4252GandthetrailingB737.Theapproachcontrollerwasrequiredtocontinue

tomonitorspacingonfinalevenafteraircraftwereswitchedtothetower.Hewasworkingfiveorsix

otheraircraft,andnoticed thatN4252Gstill seemed tobeheaded toward theoutermarker, sohe

called the tower to have them turn the aircraft direct to the runway. N4252G showed a 120kts

TUGrazIMasterthesis

HAppendix

H-11

groundspeedtoabout3milefinal,thenstartedreducingspeed.Hetoldthenextjetarrivaltoreduce

speedto150kts,andtoldthepilottocontactthetower.

After N4252Gwent around on runway 4, the I90 – Approach Controller received a call fromHOU

toweraskinghimtoslowthenextarrivaltorunway4duetoN4252Glanding.Thefinalwasfairlyfull

out toabout20NM.The I90–ApproachControlleradvised theHOUcontroller thathewouldwork

N4252G,butHOUsaidtheywouldkeeptheaircraft.

TheI90–ApproachControllertoldthetowerhecouldnot issuethereduction,anddidnotslowthe

nextarrivalbecausetheaircraftwasalreadyatthefinalapproachfixandhedidnotthinkthatHOU

towercouldsequenceN4252Ginsideofthetraffic.HeswitchedthenextarrivaltoHOUtower.Hefirst

recognized that N4252G was landing runway 35 when he saw the aircraft turning final for that

runway,priortowhichhethoughtthetowerwasgoingtohaveN4252Glandonrunway4.

The I90 – Approach Controller said that HOU tower has control for speed changes of aircraft on

contact,withnorequirementforHOUtowertocoordinatethespeedchangeswithapproachcontrol.

Itisnormalpracticetorestrictarrivalsto170ktsonfinal.

Intheeventofago-aroundbyanaircraftoperatingunder instrumentflightrules,mostofthetime

thetowerwouldswitchtheaircraftbacktoapproach.IftheaircraftwasoperatingVFR,HOUtower

wouldusuallyworktheaircraftbackinforlanding.Iftheycouldnotdothat,thenI90wouldtakethe

go-aroundaircraftbackandre-sequenceitforanotherapproach.

TheI90–ApproachControllerwasfirstinformedabouttheaccidentbyanothercontrollerwhoheard

about it while on a break (rf. (NTSB, Air Traffic Control, Group Chairman's Factual Report,

CEN16FA211,2016,p.29,30)).

TUGrazIMasterthesis

IAppendix

I-1

APPENDIXI

SummaryofCFIStatements

ReferringtothepublisheddocumentintheNTSBDMScalled“CFIStatements”(2016),thecontentof

the informationfromtwoCFIs thathadflownwiththepilotofN4252G inthepast (in thiscontext

solelycalledthepilot)wassummarizedbytheauthorasfollows:

CFI-1:

Recentflightswiththepilot:September15,23and28,2015

These three flightswereconsidered the first flightsofher instrument training.Theyhadapre-and

post-flightdiscussionwithevery lesson.Specifically,before the lessononSeptember15,2015, they

talked about checklists, pre-flight, basic instrument control and reviewed the PAVE and IMSAFE

checklists.OnSeptember15,2015 theydidclimbs, turns,descents, instrumentscan,pre-andpost-

flightanddiscussedcollisionavoidanceandrunwayincursions.OnSeptember23,2015,theydidmore

of the sameandadded compass turns, timed turnsand introducedVORs.OnSeptember28, 2015,

theydidVORinterceptingandtracking.

NTSBaskedtheCFI-1whetherthesethreeflightscouldbeconsideredabiennialflightreview,which

wasansweredasno.

WhenaskedabouttheexperienceofCFI-1 intheCirrus, itwasansweredthattheCFI-1hadbeena

CirrusTrainedInstructorandhadover1100hoursofdualgiven,80hoursofwhichwasinaCirrus.

ThefinalquestionaskedwaswhethertheCFI-1hadseenthepilot inastressfulsituation.TheCFI-1

answeredthateverysituationinwhichtheyhadbeenwashandledbythepilotwithcomposureand

thecontrolof theairplanewasmaintained,comparablewithanystudentwithwhomtheCFI-1has

worked.

CFI-2:

Recentflightswiththepilot:onceonAugust4,2014andonceonSeptember24,2014

TheCFI-2flewwiththepilotonlytwiceafterbeingcertificated.Bothflightswererecurrenttraining

flights, but neither flight would complete the requirements of Title 14 CFR part 61.56 for a flight

review.

Regardingthepilot’sabilitytohandlestressfulenvironments,theCFI-2onlyflewahandfuloftimes,

and the few times when a stressful situation was observed the pilot handled it within acceptable

levelsandretainedcomposureandtheabilitytoflytheairplane.

TUGrazIMasterthesis

IAppendix

I-2

In terms of qualifications, the CFI-2 has been a Chief Instructor for a Cirrus Training Center, and a

qualifiedCirrusStandardizedInstructorPilot.TheexperienceoftheCFI-2is400hoursindualgivenin

Cirrus aircraft, 500 hours Cirrus total hours and 2900 hours overall (rf. (retrieved from

https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60618&CFID=2395938&CFTOKEN=81732

fd00bba5423-5AB1BC7B-CB39-E91F-3732EB517FD2FBDB,CFIStatements,2016,p.1,2)).

TUGrazIMasterthesis

JAppendix

J-1

APPENDIXJ

RecordedFlightData

ReferringtotheNTSB,CockpitDisplay(s)–RecordedFlightData(2017)document,theGarminG1000

Integrated Flight Deck in N4252G included a data-logging feature. The SD memory card was

recoveredandingoodconditionandthedatarecordswereextracted.Itcontained820logfiles.The

accident flight recording was the last file recorded and it contained approximately 3hours and

10minutesofdatarecords.Additionally,aHeads-UpTechnologiesRDMdatarecorderwasmounted

in the tailof theaircraft,which isa lightweight impactand fire-hardened recorder. It is capableof

recordingapproximately150hoursofaircraftdataata rateofone recordper second.Each record

includesapproximately105positional,aircraftflightandengineparameters.Anexteriorexamination

revealed that the unit had not sustained any impact or heat/ fire damage. The unit powered up

normally and the recorded information was extracted using themanufacturer’s software, without

difficulty.

“The data extracted included 522220 total data records. The accident flight was the last session

recorded(approximately12000totaldatarecords(seconds))(rf.(NTSB,CockpitDisplay(s)-Recorded

FlightData,2017,p.2,3)).

For the STAMP (Leveson, 2011) modeling of this accident, the availability of flight data in an

electronic coded format supported the author in the analysis. For this reason, the data was

downloadedviatheDMSoftheNTSBwebsiteandanalysedindetail,inboththerawdatatablesand

subsequentlygraphicallyintheformofdiagrams.FordetailsrefertotheChapter2.2.

TUGrazIMasterthesis

KAppendix(SystemComponents)

K-1

APPENDIX(SYSTEMCOMPONENTS)KThis appendix provides basic descriptions of each individual system component, which was

consideredinmodelingoftheN4252Gaccident:

TrainingOrganisation

“Pilot training is availableon-site atmost airports in theUSA, either throughan FAA-certificated46

(approved) pilot school or through other47 training providers. […] Enrollment in an FAA-approved

pilot school usually ensures a high quality of training. Approved schools must meet prescribed

standardswith respect toequipment, facilities,personnel,andcurricula.However, individual flight

instructorsand trainingcompanies thatarenotcertificatedby theFAAas“pilot schools”mayalso

offerhighqualitytraining,butfindit impracticaltoqualifyforFAAcertification.Anotherdifference

between training provided by FAA-approved pilot schools and other providers is that fewer flight

hours are required to be eligible for a pilot certificate when the training is received through an

approvedschool”

(FAA.gov,retrievedfromhttps://www.faa.gov/training_testing/training/pilot_schools/,2019).

ATCControlService

“Air traffic control service is a service provided for the purpose of preventing collisions between

aircraft and on the manoeuvring area between aircraft and obstructions and for the purpose of

expeditingandmaintaininganorderlyflowofairtraffic”(ICAO,Annex11,2016,p.1-3).

AircraftManufacturer(Cirrus)

“AsofApril2018,thecompanyhaddeliveredover7,000SR-aircraftinnearly19yearsofproduction,

and has been theworld's largest producer of piston-powered aircraft since 2013” (Wikipedia.org,

retrievedfromhttps://en.wikipedia.org/wiki/Cirrus_Aircraft,2019).

COPA

“CirrusOwnersandPilotsAssociation (COPA) isanorganisation thatwelcomes themembershipof

Cirrus owners, pilots, and enthusiasts with an interest in aviation and Cirrus aircraft issues and

events. Three main training and safety related events provided by COPA are the Cirrus Pilot

46Author’snote:fordetails,refertoTitle14CFRpart141-PilotSchools47Author’snote:fordetails,refertoTitle14CFRpart61-CertificationPilots,FlightInstructors[…]

TUGrazIMasterthesis


K-2

Proficiency Program (CPPP), the Critical Decision Making (CDM) seminar, and the Partner in

Commandseminar.

TheCPPPisdesignedtoexposeCirruspilotstosituationstheymayencounterwhileoperatingtheir

aircraft. Topics such as weather, accident review, advanced avionics, emergency procedures, and

enginemanagementarediscussedandappliedduringaCPPP.

TheCDMseminar isafacilitatedinteractivehangar-flyingsessionwherethegrouplooksatgeneral

aviationandCirrusaccidentstatistics,reviewscasestudiesofCirrusaccidents,andparticipatesinthe

reenactmentofanactualaccident.

The Partner in Command seminar has been designed to give frequent Cirrus passengers more

knowledgeregardingsafetysystemoperationsintheunlikelyeventthatthepilotincommandshould

become incapacitated. Procedures include using basic radio communication and CAPS activation”

(FOM-SR20,2011,p.2-3,2-4).

HOUAirport

“William P. Hobby Airport […]HOU is an international airport in Houston. […]Hobby is Houston's

oldest commercial airport and was its primary commercial airport until Houston Intercontinental

Airport[…]opened”

(Wikipedia.org,retrievedfromhttps://en.wikipedia.org/wiki/William_P._Hobby_Airport,2019).

Operator/AircraftOwner

Itcouldnotbeverifiedunderwhichpre-requisitestheoperator/aircraftownerpermittedthepilot

tooperatetheaircraft.

Pilot

Forpersonaldetailsregardingthepilotoftheaccidentaircraft,refertoDAppendix.

Passengers

TheofficialNTSB accident report provided no details about the passengers on board the accident

aircraft.Recherches48by theauthorof this thesis revealedthat thepassengers (twomales,age52

and 27) were family members of the pilot, with the purpose of visiting a close relative who was

48Retrievedfromhttp://www.kathrynsreport.com/2016/06/cirrus-sr20-n4252g-safe-aviation-llc.htmlandhttps://www.dailymail.co.uk/news/article-3636188/Ma-ma-straighten-straighten-Tragic-words-woman-piloting-plane-husband-brother-filmed-crashing-killing-three.html

TUGrazIMasterthesis


K-3

receivingcancertreatmentinHouston(rf.(PassengerRecherches,2019)).Itcouldnotbeascertained

whetheranyofthepassengershadbeenalicensedpilotorpossessedpilot-relatedknowledge.

AircraftSR20

“TheCirrusSR20isanAmericanpiston-enginefour-or-five-seat,compositemonoplanebuiltbyCirrus

AircraftofDuluth,Minnesotasince1999.TheSR20wasthefirstproductiongeneralaviationaircraft

equipped with a parachute to lower the airplane safely to the ground after a loss of control,

structural failure or mid-air collision. It was also the first manufactured light aircraft with all-

composite construction and flat-panel avionics” (Wikipedia.org, retrieved from

https://en.wikipedia.org/wiki/Cirrus_SR20,2019).

TUGrazIMasterthesis

LAppendix(Illustrations)

L-1

APPENDIX(ILLUSTRATIONS)LFigure6-1illustratesaschematicoftheHOUAirport.

(HOU-ATCT-0064,2018,p.40)

Figure6-1HOUairportdiagram

TUGrazIMasterthesis


L-2

Figure 6-2 illustrates the Guidance for establishing personal weather minimums for Cirrus Pilots,

whichwasretrievedfromSR20FlightOperationsManual(2011).

(FOM-SR20,2011,p.2-6)

Figure6-2GuidanceforestablishingPersonalWeatherMinimums

TUGrazIMasterthesis


L-3

Figure6-3 illustrates theEnvelopeofSafety forCirrusPilots,whichwas retrieved fromSR20Flight

OperationsManual(2011).

(FOM-SR20,2011,p.2-7)

Figure6-3EnvelopeofSafety

TUGrazIMasterthesis


L-4

Figure6-4 illustratesadiagram to calculate thewindcomponents,whichwas retrieved fromSR20

Pilot’sOperatingHandbook(2015).

(POH-SR20,2015,p.5-13)

Figure6-4Windcomponentdiagram

TUGrazIMasterthesis

MAppendix(ATCTranscript)

M-1

APPENDIX(ATCTRANSCRIPT)MThefollowingTable6-1summarizestheATCtransmissionsfromthefirstgo-arounduntiltheaccident

asretrievedfromHOUTowerAccidentPackageN4252G(2018).

CDT COM ATCTransmission/Note RY12:57:02 LCI “justgo-aroundandflyrunwayheadingfornow,maintainVFR,andI’mgoingtoputyouback

onthedownwindforrunway35.Thewindsare090at13gusts18.Canyouacceptrunway35?”4

12:57:15 52G “We’retogo-aroundandlineupforrunway35downwind” 35

12:57:20 LCI “N4252G,flyrunwayheadingforrunway4forrightnow” 35

12:57:23 52G “We'llflyrunwayheadingfor4,4252G” 35

12:57:34 LCI “N52Gwhenablegoaheadandmakearightdownwindnowforrunway35andthenwe’lljustgoaheadandkeepthatrightturn,runway35clearedtoland”

35

12:57:46 52G “OK,makearightdownwindforrunway35?” 35

12:57:50 LCI “N52Gyesandjustkeeptherightturnallthewayaround,you’rejustgoingtorollrightintothebaseforrunway35,clearedtoland.I’vegotanother737on5milefinaltorunway4andyou’regoingtobeinfrontofhim”

35

12:58:06 52G “...turningaroundforrunway35” 35

12:58:10 LCI “...justenterthedownwindforrunway35,”andthepilotacknowledged 35

12:58:16 LCI “I'llcallyourrightbasenow” 35

12:58:48 LCT “Cirrus52G737atyour2:00o’clockand3milesat900ftinboundforrunway4advisethattrafficinsight”

35

12:58:56 52G “Ihavetrafficsight,4252G” 35

12:58:58 LCT “52Gmakearightbasebehindthattrafficrunway35clearedtolandyou'regoingtobelandingthecrossingrunwaypriortoyourarrival”

35

12:59:07 52G “We'llmakearightbasefollowingthem4252Gfor35” 35

12:59:20 LCT “Cirrus52Gmakeaturnleftheading30degrees” 35

12:59:26 52G “Leftheading30degrees4252G” 35

12:59:30 LCIasksthepilotifshe,“...wantedtofollowthe737torunway4?” 35

12:59:35 52G “yesthatwouldbegreat,4252G” 35

12:59:38 LCI “Followthe737andtorunway4clearedtoland” 412:59:45 52G “AmIturningarightbasenow,4252G?” 4

12:59:48 LCI “N52Groger,justmaneuverbackforthestraight-in,Idon’tknowwhichwayyou’regoingnow,sojustturnbackaroundtorunway35”.

35

12:59:56 52G “Turningto35,I’msosorryfortheconfusion,4252G”. 35

13:00:00 LCI “That’sOK,we’llgetit” 35

13:00:13 LCI “Cirrus52Gwhichwayareyouturningnow?” 35

13:00:18 52G “IthoughtIwasturningarightbasefor35,4252G” 35

13:00:22 LCI “...that’sfine52G,uh,justmakeituh,yousayyou’reinarightturn,keepittight,Ineedyoutomakeittight”

35

13:00:29 52G “Keepingturntight,4252G” 35

13:00:31 LCI LCIprovidedatrafficalertto“0GA”abouttraffic1mileawayat900ft,whichwasN4252G.Thatpilotreportedthatshewas“looking”

35

13:00:37 LCI “N52GIneedyoutouhthereyougo,straightintorunway35,clearedtoland” 35

13:00:43 52G “Straightintorunway35andIdon’tbelieveI’mlinedupforthat” 35

13:00:49 LCI “Okay52Grogerturntotherightandclimbandmaintain1600,rightturn” 35

13:00:57 52G “1600rightturn4252G” 35

13:01:00 LCI “Yes,ma’am,headingabout040,which52Greadbackcorrectly 35

13:01:16 LCI “OK52G,let’sdothis.Canyoudoarightturnbacktojointhestraight-into35?Couldyoudoitlikethat?”

35

TUGrazIMasterthesis

MAppendix(ATCTranscript)

M-2

CDT COM ATCTransmission/Note RY13:01:25 52G “Yes,rightturnbackto35,N4252G” 35

13:01:29 LCI Thecontrollerinstructedthepilottomakearightturn,“allthewayaroundtorunway35,”andagainclearedthepilottoland.Thepilotacknowledged.

35

13:01:37 52G “35clearedtoland4252G”,repliedby52Gwith“thankyou”.Atthesametime,theHobbyFinalcontrollerwascallingthetowertoofferaspacetoputN4252Gbehindanotheraircraft,N4JJ,inboundontherunway4final.TheLCIcontrollerdidnotrespondtothatcall.

35

13:01:44 LCI N4JJcontactedthetoweronavisualapproachtorunway4.TheLCIcontrollertoldthepilottoreducetominimumspeed,andadvisedthathewouldbenumber2fortheairportfollowingaCirruson1milefinalforrunway35.ThepilotofN4JJacknowledgedtheinformation.

35

13:02:02 LCI “Cirrus52G,OK,you’relookinggoodjustcontinuearightturnforrunway35.Doyouseerunway35still?”

35

13:02:10 52G “Yes,35,4252Ghaveitinsight,continuingmyrollaround” 35

13:02:14 LCI “Yes,ma’am,yeahyou’regoodsoyoucanstartyourdescenttorunway35there,anduhclearedtolandon35”

35

13:02:21 52G “Clearedtolandon35,52G,thankyouverymuch” 35

13:02:25 LCI “Noproblemswindsareonezerozeroatonezero,I'msorrywindsareonezerozeroatonefiveguststotwozero”

35

13:02:30 52G “OKthankyou,tryingtolosealtitude,4252G” 35

13:02:38 LCI “Noproblem,littlebitofwindofftheright” 35

13:03:01 LCI “N52Gifyoudon’twanttoland–ifthat’stoohigh,wecanputyoubackaroundthedownwind,don’tforceitifyoucan’t”

35

13:03:08 52G “OK–we’llsee,thankyou,4252G” 35

13:03:28 LCI “OK,Ithinkyou’retoohigh,Cirrus52G,youmightbetoohigh” 35

13:03:32 52G “OK–we’llgo-aroundthen,N4252G” 35

13:03:44 LCI “Cirrus52G,roger,justuhokaymakeyou'rejustgoingtomakearighttrafficnowforrunway35we'llcomebackaroundandwegotitthistime”

35

13:03:53 52G “Soundsperfect,righttrafficforrunway35,4252G” 35

13:04:38 LCI thecontrollerclearedN4252Gtoland,stating,“...makerightdownwindtorunway35,andyouareclearedtoland–therewillbenoothertrafficforrunway4sothisonewillbeeasy”

35

13:04:48 52G “Makingrighttrafficfordownwindforrunway35,4252G” 35

13:04:53 LCI “...affirmative,andclearedtolandonrunway35viatherightdownwindandrightbase” 35

13:05:02 52G “Thankyou–rightdownwind,rightbase,runway35,4252G” 35

13:06:00 LCI “...there’sa737onshortfinalrunway4touchingdownrightinfrontofyousojustcautionwaketurbulencerightthereatthatintersection”

35

13:06:08 52G “OK,Igotthatinsight,N4252G” 35

13:07:01 ApositionreliefbriefingoccurredontheLCpositionandanewcontroller(LC)tookover. 35

13:07:03 LCI ThecontrolleraskedifthepilotofN4252Ghadrunway35insight. 35

13:07:07 52G “Runway35insight,4252G” 35

13:07:10 LCI “winds090at13gust18,runway35again,clearedtoland” 35

13:07:18 52G “35clearedtolandtryingtoget[laugh]downagain,4252G” 35

13:07:22 LCI “noproblem” 35

13:08:20 52G “4252G,goingaroundagain,thirdtimewillbeacharm” 35

13:08:25 LCC “OK,Cirrus52G,justgoaheadandmaketheleftturnnowtoenterthedownwind,midfielddownwindforrunway4,ifyoucanjustkeepitinanicetightlowpattern,I’mgoingtohavetraffic4milesbehindyousoIneedyoutojustkindofkeepitintightifyoucould”

35

13:08:41 52G “OK,thistimeI'llberunway4,turningleft,4252G” 4

13:08:45 LCC “YeahandactuallyImightendupsequencingyoubehindthattraffic,he’son4milesaminute,umitisgonnabeabittightwiththeonebehinditso,uh,whenyougetonthedownwind,stayonthedownwindandadvisemewhenyouhavethat737insight.We’lleitherdo4orwemightswingyouaroundto35uhuhma’am,ma’amuhstraightenupstraightenup!”

4

(HOU-ATCT-0064,2018,p.44-49)

Table6-1SummaryofATCtransmissions,12:57:02-13:08:45CDT

wolfgang loppitsch stamp modeling of the accident n4252g

Documents