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Time of India

Dual-engine failure or human error? Pilots on edge over cause

Kolkata: Experienced pilots, awaiting investigation results of the Air India Dreamliner crash in Ahmedabad, suggest two possible causes: an extremely rare simultaneous engine failure or incorrect cockpit response during an emergency, after eliminating other scenarios. "What is clear from the visuals, especially the airport CCTV footage, is that the aircraft took off normally before experiencing a loss of lift possibly due to loss of thrust on both engines. This can happen only if both engines stall," said an Air India captain, adding the sound of the plane from an amateur video suggested the whine of a Ram Air Turbine (RAT), a backup power source deployed automatically in the B-787 aircraft when it detects loss of both engines. The captain explained the B-787's sophisticated, multiple backup systems made engine stalling due to electrical or software issues unlikely. The auxiliary power unit can be activated. Fuel contamination is unlikely during take-off when fuel flow is maximum. Also planes have dual independent fuel systems and cross-feed capabilities. An IndiGo veteran dismissed incorrect flap and slat deployment or landing gear retraction issues as causes. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Play Chess on Your PC, Free Play Classic Chess Install Now Undo "Any of this would have caused a drag but not caused the aircraft to fall off the sky. In any case, there will be alerts if there is an incorrect setting for pilots to take corrective measures," the pilot said. Pilots dismissed bird strikes, noting no visible large bird flocks in CCTV footage. "The US Airways flight had run into a flock of Canada geese that got sucked into both engines and caused them to stall. The plane captained by Chesley 'Sully' Sullenberger had touched down on the Hudson river. This did not happen in Ahmedabad as there was no fire visible or smoke trail from the engine visible in the video footage," a retired AI pilot said. Dismissing sabotage theories, commercial pilots proposed a scenario, where one engine's failure during take-off led to incorrect cockpit actions, resulting in thrust loss in both engines. "A pilot of an IndiGo flight, which was next to the Ahmedabad runway, reported a loud bang to the ATC around V1. The V1 is the take-off decision speed after which a pilot can no longer stop the aircraft but must continue with the take-off. A compressor stall could have taken out one engine. Or it could have been some other reason. After take-off, the plane climbed on the second engine. The pilot usually reports the engine loss to the ATC, turns around and lands. From the visuals, we know the plane encountered a sudden loss of lift during initial climb-out and then started to descend. This could have been due to the thrust lever of the live engine being pulled back that left the plane without any thrust," the pilot said, adding this mistake is not uncommon during simulator training. Another pilot supported this possibility, explaining engine failure procedures during take-off required pilots to take action to secure the failed engine from further damage when the aircraft reached 400 ft. If thrust is pulled back from the live engine, the plane will stall. Quick thrust restoration attempts might be manageable at higher altitudes but could be fatal at 600 ft-800 ft, with not enough time for the engine to spool up and regain thrust with the plane descending at 400 ft-500 ft descent per second. Pilots reminded that what actually transpired in the cockpit and the aircraft would be known only when the Cockpit Voice Data Recorded and the Digital Flight Data Recorder were analysed. A team from the National Transport Safety Board (NTSB), US, will assist the Aircraft Accident Investigation Bureau (AAIB), along with the UK Air Accidents Investigation Branch (AAIB) and officials from the aircraft manufacturer Boeing Co. Follow more information on Air India plane crash in Ahmedabad here . Get real-time live updates on rescue operations and check full list of passengers onboard AI 171 .