Air India plane crash linked to fuel cut-off, says AAIB preliminary report

NEW DELHI: A preliminary report on the June 12 crash of an Air India Boeing Dreamliner aircraft in Ahmedabad reveals that fuel supply to both engines was cut off immediately after take-off within one second of each other, leading to a loss of thrust and crash of the aircraft. According to the report released by India’s Aircraft Accident Investigation Bureau (AAIB) on July 11, the fuel switches of Boeing 787-8 aircraft transitioned from ‘RUN’ to ‘CUTOFF’ within one second of each other that led to a loss of thrust. Unable to gain height, the aircraft crashed in the Meghani Nagar area, killing 260 people, including 19 on the ground, in what was the worst aviation disaster involving an Indian airline in four decades. The sole survivor from among the 242 onboard passengers and the crew was a British-Indian man seated in row 11A. This was the first fatal crash of a Boeing 787 since its commercial debut in 2011. The 15-page preliminary probe report by the AAIB points to a series of possibilities and also raises multiple questions on what transpired inside the doomed flight. The report says that in the cockpit voice recording, one unidentified pilot asked the other why he had cut off the fuel, which the other denied.

On June 12, the London-bound Dreamliner began to lose thrust almost immediately after taking off from the Ahmedabad airport and ploughed into a medical college hostel. According to a chronology laid out in the report by AAIB, both fuel control switches - which are used to turn the engines off - were moved to the cutoff position almost immediately after takeoff. The report however did not say how this happened or who did it. Soon after a RAT pump was deployed to supply hydraulic power as both engines fell below minimum idle rate. About 10 seconds later, Engine 1 fuel cutoff switch moved to its so-called RUN position, followed by Engine 2 four seconds later. The pilots managed to relight both engines, but only Engine 1 recovered while Engine 2 failed to build up enough power again to reverse deceleration. One of the pilots issued a “Mayday, Mayday, Mayday” distress call but before air traffic controllers could get a response about what had gone wrong, the plane crashed just outside the Ahmedabad airport boundary having grazed some trees before plunging into a hostel packed with students. At the time the aircraft took off, the co-pilot was flying the plane, while the captain was monitoring. The time between the takeoff and the crash was only about 30 seconds. The preliminary report by AAIB released on Saturday, recommended no action for now for the operators of Boeing 787-8 planes. “The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC (13.38 IST) and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec,” the report said.

As per the report, the engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. “In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so,” it said. Almost immediately after the plane lifted off the ground, CCTV footage shows a backup energy source called ram air turbine (RAT) had deployed, indicating a loss of power from the engines. The report provided only a limited picture of the interaction between the two pilots in the flight deck and also did not say how the switches could have flipped to the cutoff position during the flight. The report did not indicate there was any emergency requiring an engine cutoff. The report said both fuel switches were found in the run position at the crash site and that there had been indications of both engines relighting before the low-altitude crash. In a statement, Air India said it was “working closely with stakeholders, including regulators” and “continue to fully cooperate with the AAIB and other authorities as their investigation progresses.” On its part, Boeing said: “Our thoughts remain with the loved ones of the passengers and crew on board Air India Flight 171, as well as everyone affected on the ground in Ahmedabad. We continue to support the investigation and our customers.” The US National Transportation Safety Board noted that there were no recommended actions in the report aimed at operators of Boeing 787 jets or the GE engines. The flight was commanded by Sumeet Sabharwal, 56, a veteran with 30 years of experience at Air India. He had logged 15,638 flying hours, including 8,596 on the Boeing 787. He was also an Air India instructor. His co-pilot was Clive Kunder, 32, who had 3,403 hours of total experience, with 1,128 on the Dreamliner. Kunder was the pilot flying, while Sabharwal was the pilot monitoring. The crew had passed pre-flight breathalyser tests and were seen at the gate on CCTV before they took off, the report adds. The June 12 accident was India’s worst aviation disaster in almost four decades and the industry’s deadliest in 11 years, as well as the first fatal involving a Boeing Dreamliner. The investigation was conducted with assistance from the UK’s Air Accident Investigation Branch and the US National Transportation Safety Board.

Aviation experts have said it is difficult for pilots to inadvertently move the fuel switches as there is a little mechanical gate built into the switch. Switches need to be lifted up over this little gate to shut off supply. They also asked why the report made no reference to cockpit camera footage. The AAIB report cited a FAA airworthiness bulletin from 2018 on the “potential disengagement of fuel control switch locking feature” on Boeing planes including the 737 and 787. The Air India jet was not inspected for the locking mechanism fault as it was never mandatory and that there has been no defect reported pertaining to the fuel control switch since 2023, it said. In the report, AAIB also said fuel samples taken from bowsers and tanks used to refuel the aircraft were tested at the DGCA Lab and were found satisfactory. The AAIB said the wreckage site activities, including drone photography/ videography have been completed and the wreckage has been moved to a secure area near the airport. “Both engines were retrieved from the wreckage site and quarantined at a hangar in the airport. Components of interest for further examinations have been identified and quarantined,” it said. According to the report, fuel samples taken from the bowsers and tanks used to refuel the aircraft were tested at the DGCA’s Lab and were found satisfactory. The AAIB is gathering additional details based on initial leads and data downloaded from the forward Enhanced Airborne Flight Recorder (EAFR) is being analysed. “At this stage of investigation, there are no recommended actions to B787-8 and/or GE GEnx-1B engine operators and manufacturers,” the report said. The plane that crashed was powered by GEnx-1B engines. Statements of the witnesses and the surviving passenger have been obtained by the investigators. The complete analysis of post-mortem reports of the crew and the passengers is being undertaken to corroborate aeromedical findings with the engineering appreciation, the AAIB said.