An Air India pilot denied switching the engines to cut off just seconds before the 787 crashed after takeoff, an investigation has found.
A preliminary report on the crash said that both engines lost fuel supply moments after the aircraft lifted off the ground.
It also revealed that Air India engineers had attended to a fault on the plane just an hour before the flight’s scheduled departure from Ahmedabad airport in Gujarat.
All but one of the 230 passengers on board the flight bound for London Gatwick were killed in the disaster, which also claimed the lives of 19 people on the ground and injured a further 67.
The pilots of the previous flight had flagged an error with the plane’s stabiliser sensor, which indicates the horizontal trim setting.
The report confirmed that Air India Flight 171 had reached a maximum airspeed of 180 knots when the fuel supply to both engines was cut off within a second of each other.
Cutoff switches are usually only deployed to power down engines after landing or in the event of an emergency in the air, such as an engine fire.
CCTV footage from the airport showed the aircraft’s backup Ram Air Turbines (RAT) were activated after the engines cut out.
Analysis of the cockpit voice recorder found that one of the pilots asked his colleague why he had cutoff the engines, to which they responded they hadn’t.
Within a minute of the engines switching to cutoff, the crew responded and put them back into ‘run’ mode in an attempt to restart them.
However less than ten seconds later one of the pilots made a ‘mayday’ call to ATC.
A question by the ATC operator about the aircraft’s call sign went unanswered and the plane crashed just outside the airport’s boundary at a residential hostel.
The aircraft was airborne for a total of 40 seconds before it smashed into the ground.
Investigators from India’s Air Accident Investigation Bureau have focussed on the 787’s fuel control locking feature, which is supposed to prevent accidental deployment during flight.
The system, designed originally in the 1950s, requires pilots to pull up the switch before being able to flip it.
A notice was issued by the US’s FAA in 2018 following reports that the feature was installed disengaged on some 737 aircraft.
However Air India did not undertake the recommended inspections as they were not mandatory, the Flight 171 report stated.
There had been no reports of defects on the fuel control switch in the accident aircraft since 2023.
However an unnamed air accident investigator based in Canada suggested the simultaneous deployment of the switches made this crash particularly unusual.
They told the BBC: ‘It would be almost impossible to pull both switches with a single movement of one hand, and this makes accidental deployment unlikely.’
Aviation expert Keith Tonkin said it was ‘inexplicable’ that a pilot would flip the switch just after take off.
He told ABC News Australia: ‘It’s important to have fuel flowing to the engines, unless you turn them off in the event of an emergency where the procedure requires that. It would not normally be done and it’s a deliberate decision to do that.’
It was the first major incident on a Boeing 787, which entered service in 2014.
The aircraft operating Flight 171, VT-ANB, was manufactured in 2013. Both of its engines had been replaced this year – the left hand side in May, just weeks before the crash.
The investigation has so far ruled out several possible factors, including weather conditions, which were found to be normal during the time of the flight.
The 787 was found to be within acceptable weight limits and not carrying any dangerous goods, and both the pilot and first officer were both adequately rested and declared to fit to fly following a breath analyser test an hour before departure.
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