The preliminary report by the Aircraft Accident Investigation Bureau (AAIB) did not recommend action against the manufacturer Boeing, or engine supplier General Electric, indicating no major fault with the plane or its engines, aviation safety experts said.
AAIB said analysis of the aircraft’s cockpit voice recorder (CVR) and flight data recorder (FDR) showed both fuel control switches, which regulate flow to the engines, had been disengaged seconds after lift-off.
Ten seconds later, the switches were turned on again, but the plane failed to regain power fast enough to stop its descent, before crashing.
The fuel cut-off switches in a modern aircraft such as the Boeing 787 are located below the thrust lever and have safeguards such as a metal lock, as well as a guard built around them, to avoid accidental switching off. The safeguards were built in after multiple incidents of unintentional fuel shut-off on older generation planes.
The report also pointed to apparent confusion over the rapidly-unfolding scenario between the two pilots. “In the CVR, one of the pilots is heard asking the other why he cut off. The other pilot responded that he did not do so,” the report said.
Sumeet Sabharwal, with more than 15,000 hours of flying experience, was the captain of Air India flight AI71 on a scheduled service from Ahmedabad to Gatwick. First Officer Clive Kunder had 3,400 hours of flying experience, according to Air India.
ET BureauThe AAIB report did not offer any final conclusion about the factors that could have led to the fuel switches getting turned off.A person aware of the development said investigators will now determine whether any software problem with the plane’s control could have led to the confusion. The person pointed to the possibility of a second interim report if there are more significant findings, but safety experts said investigators have more or less determined the cause to be human error. “It’s not Boeing or the engines, as we can see from the fact that there have been no recommendations for them,” said John Goglia, a former member of the National Transportation Safety Board of the US.
ET BureauIntentional Or Not
“They clearly say somebody turning fuel switches off at an inappropriate moment. I believe the investigation will now focus on determining whether the act was intentional,” said Goglia.
Goglia said the presence of an aviation psychologist at the initial stage of an air crash probe is very unusual, and indicates the investigators were focusing more on the angle of human error.
The AAIB team probing the crash also comprises a psychologist. Air India said it will fully cooperate with investigators.
“Boeing will defer to India’s AAIB to provide information about Air India Flight 171, in adherence with the United Nations International Civil Aviation Organization protocol known as Annex 13,” the American aircraft manufacturer said.
FAA’s 2018 recommendation
AAIB also noted that the US Federal Aviation Administration (FAA), in 2018, recommended airlines inspect the fuel control switches on the 787 and other Boeings, after a few airlines reported incidents of the fuel-locking mechanisms getting disengaged. The FAA, however, mentioned the recommendations were not mandatory.
Fuel switches changed
Moreover, the fuel switches on the crashed plane had been changed when Air India replaced the throttle control module — once in 2019 and then in 2023. A maintenance record of June 11 for the same aircraft, a day before the crash, did not reveal any fault with any critical part.
