Causes and Contributing Factors
Causes
Causes are actions, omissions, events, conditions, or acombination thereof, which led to this accident.
3.2.1 A large fire developed in palletized cargo on themain deck at or near pallet positions 4 or 5, in Fire Zone 3, consisting ofconsignments of mixed cargo including a significant number of lithium typebatteries and other combustible materials. The fire escalated rapidly into acatastrophic uncontained fire.
3.2.2 The large, uncontained cargo fire that originatedin the main cargo deck caused the cargo compartment liners to fail under combined thermal and mechanicalloads.
3.2.3 Heat from the fire resulted in the system/componentfailure or malfunction of the truss assemblies and control cables, directly affecting thecontrol cable tension and elevator function required for the safe operation of the aircraft when inmanual control.
3.2.4 The uncontained cargo fire directly affected theindependent critical systems necessary for crew survivability. Heat from thefire exposed the supplementary oxygen system to extreme thermal loading,sufficient to generate a failure. This resulted in the oxygen supply disruptionleading to the abrupt failure of the Captain’s oxygen supply and theincapacitation of the captain.
3.2.5 The progressive failure of the cargo compartmentliner increased the area available for the smoke and fire penetration into thefuselage crown area.
3.2.6 The rate and volume of the continuous toxic smoke,contiguous with the cockpit and supernumerary habitable area, resulted in inadequatevisibility in the cockpit, obscuring the view of the primary flight displays, audio control panelsand the view outside the cockpit which prevented all normal cockpit functioning.
3.2.7 The shutdown of PACK 1 for unknown reasons resultedin loss of conditioned airflow to the upper deck causing the ElectronicEquipment Cooling [EEC] system to reconfigure to “closed loop mode”. The absence of a positive pressuredifferential contributed to the hazardous quantities of smoke and fumes entering the cockpit andupper deck, simultaneously obscuring the crew’s view and creating a toxic environment.
3.2.8 The fire detection methodology of detecting smokesampling as an indicator of a fire is inadequate as pallet smoke masking can delay the time ittakes for a smoke detection system to detect a fire originating within a cargo container or apallet with a rain cover.
3.3 CONTRIBUTING FACTORS
Contributing factors. Actions, omissions, events,conditions, or a combination thereof, which, if eliminated, avoided or absent, would have reduced theprobability of the accident or incident occurring, or mitigated the severity ofthe consequences of the accident or incident.
The identification of contributing factors does not implythe assignment of fault or the determination of administrative, civil or criminalliability.
3.3.1 There is no regulatory FAA requirement in class Ecargo compartments for active fire suppression.
3.3.2 Freighter main deck class E fire suppressionprocedures which relay on venting airflow and depressurisation as the primary means of controlling afire are not effective for large Class E cargo fires involving dangerous goodscapable of Class D metal fire combustion.
3.3.3 No risk assessment had been made for the failure ofthe cargo compartment liner based on the evolution of cargo logistics andassociated cargo content fire threats, cargo hazards and bulk carriage ofdangerous goods.
3.3.4 The regulation standards for passive firesuppression do not adequately address the combined total thermal energyreleased by current cargo in a large cargo fire and the effect this has on theprotection of critical systems.
3.3.5 FAA and EASA regulatory requirements do notrecognize the current total fire risk associated with pallets, pallet coversand containers as demonstrated by the NTSB/FAA testing.
3.3.6 Class 9 Hazmat packing regulations do not addressthe total or potential fire risk that can result from lithium battery heatrelease during thermal runaway. Although non-bulk specification packaging isdesigned to contain leaks and protect the package from failure, the packagingfor Class 9 does not function to contain thermal release.
3.3.7 The growth rate of container and pallet fires afterthey become detectable by the aircraft’s smoke detection system can beextremely fast, precluding any mitigating action and resulting in anoverwhelming total energy release and peak energy release rate for a standardfire load that cannot be contained.
3.3.8 The course to return to Dubai required a series ofcomplex radio communication relays due to the Pilot Flying’s inability to viewand tune the radio transceivers.
3.3.9 The relay communication between the Pilot Flying,relay aircraft and the various ATC stations resulted in communicationconfusion, incomplete and delayed communications, which contributed to the escalated workload and task saturationfor the Pilot Flying.
3.3.10 The Fire Main Deck non-normal checklist in the QRHwas not fully completed by the crew or adhered to regarding the firesuppression flight level or land at nearest airport instruction.
3.3.11 Task saturation due to smoke and multiple systemsfailures prevented effective use of the checklist by the crew.
3.3.12 Communications between the ATCO units involvedmultiple stages of information exchange by landline and the destinationaerodrome was not fully aware of the specific nature of the emergency, thedifficulty that the Pilot Flying was experiencing or the assistance required.
3.3.13 The Pilot Flying had not selected transponder code7700, the emergency code, when radio communication with the destinationaerodrome was not established.
3.3.14 Task saturation due to smoke and multiple systemsfailures prevented effective use of the checklist by the crew
3.3.15 The incapacitation of the Captain early in theevent sequence, resulted in a single pilot scenario. The numerous cascadingfailures and smoke in the cockpit resulted in task saturation and an extremeworkload for the remaining pilot.
3.3.16 The crew was not equipped with an alternativevision system or method for managing a smoke filled cockpit that would allowthe crew to view the primary instruments.