HICS

latent critical fuel scenarios

capt. raimund zoppflugwerkzeuge aviation software

• Airbus 310, Charter flight from Chania/Greece to Hannover/Germany

• Landing gear retraction fault at takeoff in Chania• Flight continuation to reach commercially favorable alternate• fuel planning exclusively by FMS• Repeated replanning to MUC and then to VIE after FMS fuel

prediction deteriorates• Early start of descent 90NM before optimum • Fuel below original final reserve and fuel low level warning abeam

ZAG, 133NM out of VIE• Emergency declared 8 minutes later• Both engine flame-out short before outer marker• Crash landing on grass 500m before runway• Only light injuries, aircraft written off

HLF 3378 (Vienna, July 2000)

HLF3378 Flightpath Overview

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aber jetzt hamm wir 800 Kilo (CVR/CM1)

Fuel low level warning (ACARS)

EFOB VIE below Holding Fuel (Estimate)

FQ below Holding fuel (Estimate)

HER

• Aircraft operated beyond range capability with landing gear down

• FMS fuel predictions used as sole means of fuel planning

• No ground support for fuel planning

• Subtle loss of situational awareness

• Violation of rules in final stage:no diversion to ZAG or GRZ when fuel quantity dropped below final reserve

official report should be available soon on http://versa.bmvit.gv.at

HLF 3378 (Vienna, July 2000)

HLF3378 Fuel Situation

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Tanks Empty

abeam ZAG

FQ Low Level Warning

EFOB VIE goes below Holding Fuel

• repeated replanning and shortcuts gave impression that FMS fuel prediction was still reliable• documentation confusing and incomplete• no other method for fuel planning considered

swiss cheese model of accident causation

according to j. reason

in the case of HLF3378, active inflight support from dispatch would have been one of the defense layers

one of several safety recommendation:(free translation from German language, since official translation not yet available)

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application of support to cockpit crew by the flight dispatcher as required by ICAO Annex 6 and the quality manual of the operator

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remaining crucial questions: • is the dispatcher obliged to support the flight crew only on request ?• does his support involve a fuel recalculation ?• can (or shall) the dispatcher initiate an emergency ?• how shall a dispatcher perform the neccessary calculations ?

HLF 3378 accident investigation

HLF3378 - just a singular case?

• actual case: gear-down diversion due to weather / hydraulic loss– loss of hydraulic system early during flight– continuation to destination with approaching frontal weather– go-around due to weather– gear retraction impossible– diversion with gear down– severe fuel situation / landing below final reserve – loss of gear retraction capability was known for hours – documentation gives no advice to adjust fuel planning

• potential case: engine fail with locked rotor– quiz: how much does the fuel burn increase?

commercial pressure as a risk factor ?

2000/07/12 HFL3378• prolonged gear down flight

from Greece to Vienna• uncritical weather• good communication• strong commercial

motivation to continue• insufficient ground support• loss of situational

awareness• all engine flame-out• crash

2005/02/19 BA268

• with a failed engine from US west coast to UK

• uncritical weather• good communication• strong commercial motivation

to continue• professional ground support

available, but not used• late, but correct decision to

abort initial goal (LHR)• successful diversion to MAN• how many lucky cases like

this get away unnoticed?

latent limitations of the 2-man cockpit

• some tasks of the flight engineer / navigator were actually never fully taken over by computers

• FMS / ECAM have severe limitations in abnormal operation

• no detailed documentation available onboard• no training about latent limitations• ICAO Annex 6 requires ground support from

dispatch• modern ground-based systems and high-quality

communication channels are available worldwide

????

latent critical scenarios - handling

• prevent- additional fuel even for non-ETOPS enroute alternates

- base diversion decisions on accurate calculations

• detect- use all available information to accurately predict potential scenarios

- follow flight progress with all available means

• assistprovide optimum tactical assistance in actual enroute diversions

- based on precise aircraft performance data for the current configuration- based on up-to-date wind forecasts- select most suitable alternate- optimize flight profile- avoid terrain

latent critical scenarios - triggers

• change in destination / enroute alternate selection• replanning without recalculation• overburning / using up of contingency fuel• rerouting / diversion• change of wind / weather conditions• change of aircraft status / configuration

- engine fail

- gear down

- flight control problems

- drag items

- fuel leak

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critical fuel scenario exceeds actual fuel

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latent critical scenarios & cost saving

• reduction of fuel reserves will bring us close to latent critical scenarios more often

• pilots instinctively uplift extra fuel for "safety reasons" – sometimes counteracting reductions of reserves

• "instinctive" extra fuel is a significant cost factor with today's high fuel prices

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credible in-flight support reduces this cost factor and ensures a high safety level even when operating under strong commercial pressure