Findings
The findings are statements of all significant conditions, events or circumstances in the accident sequence. The findings are significant steps in the accident sequence, but they are not always causal or indicate deficiencies.
1. The crew of the inbound sector from Hong Kong reporteda PACK 1 failure. This failure could not be replicated on the ground in Dubaiby the ground engineer.
2. The Boeing 747-400 fleet was experiencing a lower thanpredicted MTBF of the turbine bypass valve [TBV], which is a component of theAC PACKs.
3. A consignment of mixed cargo including a significantnumber of batteries, including lithium types, was loaded on the inbound flightfrom Hong Kong onto the pallets located at MD positions 4, 5, and 6, amongstother positions. This cargo was not unloaded in Dubai.
4. At least three shipments including lithium typebatteries should have been classified and fully regulated as Class 9 materials per ICAO TechnicalInstructions, and thus should have appeared on the cargo manifest. Theseshipments were located in the cargo at MD positions 4 and 5.
5. Shippers of some of the lithium battery cargo loadedin Hong Kong did not properly declare these shipments and did not provide TestReports in compliance with the UN Recommendations on the Transport of DangerousGoods Manual of Tests and Criteria, Section 38.3, to verify that such these batterydesigns were in conformance with UN Modal Regulations.
6. The aircraft was airworthy when dispatched for theflight, with MEL items logged. These MEL items are not contributory to theaccident.
7. The mass and the Center of Gravity [CG] of theaircraft were within operational limits.
8. The crew was licensed appropriately and no fatigueissues had been identified.
9. The Captains blood sample was positive for ethylalcohol with a concentration of (11 mg/dl).
10. Currently a universal fire protection certification standardcovers all transport category aircraft.
11. FAA Advisory Circular 25-9A Smoke Detection,Penetration, And Evacuation Tests And Related Flight Manual EmergencyProcedures does not require the consideration of continuous smoke generation forcockpit smoke evacuation, the FAA recommends that the airframe design addressthis situation but it is not mandatory.
12. The crew were heard to confirm the oxygen masksettings during preflight, however sound spectrum analysis indicated that for unknown reasons, theFirst Officer’s mask was set to Normal instead of 100%, which likely allowedambient air contaminated with smoke to enter his mask.
13. The take-off at 14:50 UTC and initial climb wereuneventful.
14. At 14:58 UTC, Pack 1 went off line and was reset 2minutes later by the PM.
15. The crew acknowledged Bahrain radar and crossed intothe Bahrain FIR at 15:11 UTC.
16. At some point prior to the fire warning, contents ofa cargo pallet, which included lithium batteries, auto-ignited, causing a largeand sustained cargo fire which was not detected by the smoke detectors when inthe early stages of Pyrolysis.
17. Pallets with rain covers can contain smoke until alarge fire has developed.
18. Two minutes after passing into the Bahrain FIR,Twenty one minutes after take-off there is a fire alert at 15:12 indicating a,FIRE MAIN DK FWD.
19. The Captain assumes control as Pilot Flying, the F.Obegins the FIRE MAIN DK FWD non-normal checklist.
20. The Capt advises the F.O they are to return to DXBbefore alerting Bahrain Area East Control [BAE-C] of the fire onboard,declaring an emergency and requesting to land as soon as possible.
21. BAE-C advised the crew that Doha airport was 100 nmto the left. The turn back to DXB totaled 185 nm track distance. The likelyoutcome of a hypothetical diversion is inconclusive.
22. At the time the Captain decided to turn back, thecrew was not yet aware of the full extent of the fire and its effects.
23. By the time that the smoke in the cockpit and firedamaged controls became apparent, diverting to Doha was no longer a feasibleoption.
24. The course to DXB resulted in the airplane flying outof direct radio communication with ATC, requiring a complex relay ofcommunication and increased task saturation for the F.O.
25. In addition to the energy release from Lithiumbatteries resulting in combustion, there is an associated mechanical energy release. This mechanicalenergy release is capable of compromising the integrity of packaging andcreating incendiary projectiles.
26. The control of the aircraft when in manual controlwas compromised due to the thermal damage to the control cable assemblies. Thefirst indication of the deteriorated synchronization problems between the controlcolumn movement and elevator position appear when the Captain disconnects theautopilot.
27. The time interval between fire detection and theonset of aircraft system failures was two minutes and thirty seconds at thepoint of detection. In all probability the fire had damaged the control cablesprior to autopilot disconnection.
28. The aircraft begins to turn on to a heading for DXBand descends. As it was dusk, the aircraft is now descending to the east andback into an easterly time zone where there is limited available ambient solarlight.
29. The cargo compartment liner failed as a fire andsmoke barrier under combined thermal and mechanical loads.
30. Consequently, the damaged cargo compartment linerexposed the area above the cargo bay in fire zone 3 to sustained thermalloading either breaching the cargo compartment liner or causing the aluminiumstructure retaining the liner to collapse, exposing the area above and adjacentto the breach to continuous thermal loading.
31. Consequently, the damaged cargo compartment linerexposed the supernumerary and cockpit area to sustained and persistent smokeand toxic fumes.
32. Based on the NTSB pallet and container testingresults, it is now known that the growth rate of container fires after theybecome detectable by the aircraft’s smoke detection system can be extremely fast, precluding any mitigating action andresulting in an overwhelming fire that cannot be contained.
33. The high thermal loading damaged or destroyed thesupporting trusses for the control cables directly affecting the control cabletension. The control column effectiveness was significantly reduced,subsequently the movement of the elevators, speed brake, rudders, brakes andlanding gear control had been compromised.
34. The high thermal loading caused damage to the ECSducting,
35. The ACARS/AHM data indicates a series of sensorfailures and fire wire loops tripping to active in the area of the fire, thefault timing and the fire warning are corollary.
36. The crew donned their oxygen masks, and experienceddifficulty hearing each other.
37. The oxygen masks had a required setting of100% and inemergency for smoke in the cockpit.
38. The oxygen selector position cannot be viewed whenthe mask is on. The technique used to determine the selector position when the mask was on wasnot an operator technique or reinforced through training scenarios and non-cognitivemuscle memory techniques.
39. The mask settings remain unchanged for the durationof the flight.
40. The main deck fire suppression system was activatedand the cabin depressurized.
41. Lithium-metal cell thermal stability and reactionsthat occur within a cell with elevated temperatures, up to the point of thermal runaway are notoxygen dependent. Electrolyte or vent gas combustion properties and the firehazards associated with thermal runaway reactions do not respond to the FL250assumed hazard mitigation methodology.
42. The Class E cargo compartment fire suppressionstrategy of preventing venting airflow in to cargo compartment,depressurization and maintaining 25,000ft cabin altitude may not be effectivefor Class D metal fires.
43. For unknown reasons Pack 1 went off and was notmentioned by the crew. The cockpit smoke prevention methodology when the firesuppression is active is to have pack one on low flow pressurizing the cockpitarea to a higher than ambient pressure, preventing smoke ingress.
44. It is unknown in this instance that if Pack one hadbeen active this method would have worked as described based on the volume andflow of the smoke The Capt requests a descent to 10,000ft
45. The QRH Fire Main Deck checklist does not address thekey factor of descend or divert decision making. The checklist fire suppressionmethodology advises the crew to remain at 25,000 cabin pressure altitude tosuppress a fire or land at nearest suitable airport. It does not provideguidance for when or how to transition to landing or the fact that descendingearly might provide more atmospheric oxygen to the fire. There is nointermediate step to verify or otherwise assess the condition of the fire andto evaluate the risk to the aircraft if a decent is initiated.
46. The Class E certification standards for firesuppression does not require active fire suppression.
47. Within three minutes of the fire alarm, smoke entersthe cockpit area. This smoke in the cockpit, from a continuous source near andcontiguous with the cockpit area, entered with sufficient volume and density tototally obscure the pilot’s view of the instruments, control panels and alert indicatingsystems for the duration of the flight.
48. Once the liner had been breached, the openings in theliner would progressively expand, allowing an increase in the volume of densenoxious smoke, fire and combustion by-products to escape the cargo compartment.
49. The cargo compartment liner structure certificationdoes not include extreme heat and other input loads such as vibration,multi-axial loading, intermittent pressure pulses, thermo mechanical loadingsbased on differential materials coefficients, acoustic and ballistic damagetesting.
50. The crew made several comments concerning theirinability to see anything in the cockpit. The crew in the smoke environment hadreduced visibility and could not view the primary instruments such as the MFD,PFD, Nav Displays or the EICAS messages.
51. The Captain selected the Autopilot on and leveled outfollowing the pitch control problems. The aircraft remained in a stable steadystate when controlled via the AP. There was no communication between theCaptain and the F.O. that the controllability problem was resolved using theAP.
52. Effective elevator and rudder control was onlyavailable with the autopilots. The aircraft was controllable with the AP as theservos are electrically controlled and hydraulically actuated, which for pitchcontrol is in the tail section aft of the rear pressure bulkhead, and the firehad not compromised the electrical cabling to the actuators.
53. The PF was not fully aware of the extent of thecontrol limitations, could not see the EICAS messages and was not aware of all of the systemsfailures.
54. The Captain called for the smoke evacuation handle tobe pulled as the smoke accumulated in the cockpit. The smoke evacuation handlewhen pulled opens a port in the cockpit roof, which if the smoke is sustainedand continuous, will draw smoke through the cockpit as the pressure is reduced bythe open port venturi effect compounding the problem. The smoke evacuation handleremained open for the remainder of the flight.
55. There are several instances of checklist interruptionat critical times at the beginning of the emergency. The speed and quick succession of thecascading failures task saturated the crew. The smoke in the cockpit, combinedwith the communications problems further compounded the difficult CRMenvironment. With the incapacitation of the captain, the situation in thecockpit became extremely difficult to manage.
56. One factor when dealing with the QRH and runningchecklists is that the B747 does not have a hot microphone function. Thiscaused increasing difficulty managing cascading failures and high workload.
57. The crew was unable to complete the Fire Main Deckchecklist. The aircraft was not leveled off at 25,000 ft. Directly descendingto the 10,000 ft may have exacerbated fire and smoke problem due to the extraavailable oxygen.
58. The Captain instructed the F.O. to input DXB RWY12Linto the FMC. This action was completed with difficulty due to the smoke. Therewas no verbal confirmation of the task completion, however, the aircraftreceivers detected the DXB Runway 12L glide slope beam when approaching Dubai.
59. Captain made a comment mentioning the high cockpittemperature, almost immediately the Captains oxygen supply abruptly stoppedwithout warning, this occurred seven minutes six seconds after the first MainDeck Fire Warning.
60. The Captain’s inability to get oxygen through hismask was possibly the result of the oxygen hose failure near the connector. Thehigh thermal loading was conducted through the supplementary oxygen stainlesssteel supply lines heating the supplementary oxygen directly affecting theflexible hose connector causing the oxygen supply line to fail.
61. Systems analysis indicates that the oxygen supply ispressure fed, therefore venting oxygen could be released by a failed oxygenhose which could then discharge until the oxygen line fails or the oxygensupply is depleted.
62. The Captain requests oxygen from the F.O. severaltimes over approximately one minute. The First Officer due to possible tasksaturation was not able to assist the Captain.
63. The oxygen requirement of the Captain becamecritical, the Captain removes the oxygen mask and separate smoke goggles andleaves the seat to look for the supplementary oxygen. The Captain did notreturn. The Captain was in distress locating the supplementary oxygen bottleand could not locate it before being overcome by the fumes.
64. The Captain was incapacitated for the remainder ofthe flight. A post-mortem examination of the Captain indicates that the causeof death was due to carbon monoxide inhalation.
65. A full face emergency oxygen supply is available inthe cockpit. Oronasal masks are available in the lavatory, jump seat area andcrew bunk area.
66. Due to the Captain’s incapacitation the F.O becameP.F. for the remainder of the flight, operating in a single pilot environment.Exposure to this type of environment in a controlled training environment couldhave been advantageous to the remaining crew member.
67. The FO had breathing difficulties as the aircraftdescended as the normal mode function of the mask supplies oxygen at a ratio toatmospheric, ambient air. The amount of oxygen supplied was proportional to thecabin altitude.
68. The cockpit environment remained full of smoke in thecockpit, from a continuous source near and contiguous with the cockpit area forthe duration of the flight.
69. As the flight returned towards DXB, the crew were outof VHF range with BAE-C and should have changed VHF frequencies to the UAE FIRfrequency 132.15 for the Emirates Area Control Center [EACC]. Due to the smokein the cockpit the PF could not view the audio control panels to change thefrequency selection for the duration of the flight.
70. The flight remained on the Bahrain frequency 132.12MHz on the left hand VHF ACP for the duration of the flight. To solve the direct line ofcommunication problem, BAE-C requested traffic in the vicinity to relaycommunication between crew and BAE-C.
71. The PF made a blind Mayday call on 121.5 MHz at 15:21UTC.
72. The PF had to relay all VHF communication throughother aircraft. The radio communication relay between the PF, the relayaircraft and the ANS stations resulted in confusion communicating the natureand intent of the PF’s request for information with the required level ofurgency.
73. The PF requested from the relay aircraft immediatevectors to the nearest airport, radar guidance, speed, height and otherpositional or spatial information on numerous occasions to gauge the aircraft’sposition relative to the aerodrome and the ground due to the persistent andcontinuous smoke in the cockpit.
74. The relay aircraft did not fully comprehend orcommunicate to the BAE-C controller the specific nature of the emergency andassistance required, particularly towards the end of the event sequence.
75. There was a multi-stage process to complete astandard request for information between the accident flight and thedestination aerodrome via the relay aircraft and the ATCU.
76. The flight crew did not or could not enter thetransponder emergency code 7700, however all ATCUs were aware that the airplanewas in an emergency status.
77. DXB controllers were aware that the flight was in anemergency status, however were not aware of the specific nature of theemergency or assistance required, due to the complex nature of the relayedcommunications.
78. There was no radar data sharing from the UAE toBahrain ATC facilities. Bahrain had a direct feed that goes to the UAE butthere was no reciprocal arrangement. This lack of data resulted in the BAE-CATCO not having radar access the SSR track of the accident flight.
79. The ATC facilities are not equipped with tunabletransceivers.
80. The accident aircraft transmitted on the Guardfrequency 121.5 Mhz. The transmissions were not heard by the EACC or DXB ATCplanners due to the volume of the 121.5 Mhz frequency being in a low volumecondition.
81. The PF did not respond to any of the calls from theACC or the relay aircraft on 121.5 MHz, which were audible on the CVR, afterthe Mayday transmission.
82. During the periods when direct radio communicationsbetween the pilot flying and the controllers was established, there was nonegative effect. Therefore it is likely that if direct 121.5 contact had beenestablished the communications task could have been simplified.
83. The relay aircraft hand off between successiveaircraft caused increasing levels of frustration and confusion to the PF.
84. All Dubai aerodrome approach aids and lightingfacilities were operating normally at the time of the accident.
85. There is no requirement for full immersion smoke,fire, and fumes cockpit training for flight crews.
86. The PF selected the landing gear handle down. Thelanding gear did not extend, likely due to loss of cable tension.
87. The flaps extended to 20°. This limited the autothrottle power demand based on the max flap extension placard speed at 20°Flaps.
88. The PF was in radio contact with a relay aircraft,who advised the PF through BAE-C that Sharjah airport was available, and a lefthand turn onto a heading of 095° was required.
89. The PF made an input of 195° into the MCP for anundetermined reason when 095° was provided. The aircraft overbanked to theright, generating a series of audible alerts. It is probable that the PF, inthe absence of peripheral visual clues, likely became spatially disorientatedby this abrupt maneuver.
90. The aircraft acquired 195°, the AP was selected off.The throttle was retarded and the aircraft began a rapid descent.
91. The PF was unaware of the large urban area directlyin the airplane’s path. The aircraft began a descent without a defined landingarea ahead.
92. Spatial disorientation, vestibular/somatogyralillusion due to unreliable or unavailable instruments or external visualreferences are a possibility. The PF was unaware of the aircraft locationspatially. The PF may have been attempting an off airfield landing, evidencedby numerous control column inputs.
93. The control column inputs to the elevators had alimited effect on the descent profile. The pilot made a series of rapid columninputs, in response to GPWS warnings concerning the sink rate and terrain. Theinputs resulted in pitch oscillations where the elevator response decreasedrapidly at the end of the flight
94. The available manual control of pitch attitude was minimal,the control column was fully aft when the data ends, there was insufficienttrailing edge up [nose up] elevator to arrest the nose down pitch. Control ofthe aircraft was lost in flight followed by an uncontrolled descent intoterrain.
95. The aircraft was not equipped with an alternativeviewing system to allow the pilot(s) to view the instruments and panels in thesmoke filled environment.
Last edited by F111UPS767; 24th Jul 2013 at 14:13.