Switches controlling the supply of fuel to the engines of the Air India flight that crashed last month were turned off seconds before impact, a preliminary investigation report released on Saturday has shown.
Data from the cockpit voice recorder showed that both pilots were confused about how the switch settings moved from the "run" to the "cut-off" position, the report by India's Aircraft Accident Investigation Bureau said.
The Air India aircraft – a Boeing 787-8 Dreamliner – crashed shortly after taking off from Ahmedabad airport on June 12, killing all but one of the 242 people on board and at least 19 on the ground.
According to the report, the flight lasted about 30 seconds between take-off and crashing. Once the aircraft achieved its top recorded speed, “the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another" within a second, it said.
One pilot can be heard in the voice recording asking the other why he cut off the fuel. "The other pilot responded that he did not do so," the report said. It did not identify which of the remarks were made by the flight's captain and which by the first officer, nor which pilot transmitted "Mayday, Mayday, Mayday" just before the crash.
The switches were flipped back to the run position, the report said, but the plane could not gain power quickly enough to avoid crashing.
The flight to London was carrying 230 passengers — 169 Indians, 53 British, seven Portuguese and a Canadian — along with 12 crew members. It crashed into buildings of a medical college near the airport.
The investigation into the incident is being led by the AAIB, an office under India's Civil Aviation Ministry, with US aviation authorities and Boeing also taking part.
The US National Transportation Safety Board thanked Indian officials for their co-operation in a statement and noted that there were no recommended actions in the report aimed at operators of Boeing 787 jets or the GE engines.
Air India said it was fully co-operating with authorities investigating the crash.
“Air India is working closely with stakeholders, including regulators. We continue to fully co-operate with the AAIB and other authorities as their investigation progresses,” it said.
The plane’s black boxes — combined cockpit voice recorders and flight data recorders — were recovered in the days following the crash and later downloaded in India.
Indian authorities also ordered intensified checks of Air India’s entire fleet of Boeing 787 Dreamliners. Air India has 33 Dreamliners in its fleet.
