A preliminary investigation report into last month’s Air India plane crash at Ahmedabad found that moments after the aircraft took off, its fuel control switches transitioned from “RUN” to “CUTOFF” within a second of each other, because of which both engines shut down.

The plane crash on June 12 killed at least 260 persons, and was said to be the world’s worst aviation disaster in a decade.

The report by the Aircraft Accident Investigation Bureau said that one of the pilots could be heard on the cockpit voice recorder asking the other why he shut down the fuel, in response to which the other pilot said that he did not.

After a gap of about 10 seconds, the switches went back to the “RUN” position, in what appeared to be an attempt by the pilots to regain thrust in the engines. Subsequently, one of the engines progressed to recovery, and deceleration stopped, but deceleration could not be stopped on the second engine.

The report said that the flight lasted for about 30 seconds from the lift-off to the crash.

The Aircraft Accident Investigation Bureau said that on December 17, 2018, the United States’ aviation regulator Federal Aviation Administration had issued an advisory about the potential disengagement of the fuel control switch locking feature. The inquiry said that on this, Air India said that the suggested inspections were not carried out as the bulletin was an advisory, and did not require mandatory action.

A scrutiny of maintenance records showed that no defect was reported in the fuel control switch on the aircraft since 2023, when the throttle control module was last replaced. The throttle control module, however, was not replaced due to the fuel control switch.

The report said that at this stage, there were no recommended actions for operators of Boeing 787-8 aircraft and GE GEnx-1B engines.

Aviation safety expert and founder of non-governmental organisation Safety Matters Amit Singh told The Hindu: “Until the investigation explains how a supposedly locked fuel switch could have moved to CUTOFF and provides a detailed sequence of failure messages and aircraft response, the full truth remains elusive.”

Air India on Saturday acknowledged having received the preliminary report of the Aircraft Accident Investigation Bureau.

“We continue to fully cooperate with the AAIB and other authorities as their investigation progresses,” the airline said. “Given the active nature of the investigation, we are unable to comment on specific details and refer all such enquiries to the AAIB.”

On June 12, Air India’s Boeing 787-8 Dreamliner aircraft, which was en route to London’s Gatwick airport from Ahmedabad, crashed just 33 seconds after taking off.

There were 242 people aboard the aircraft. One passenger survived with “impact injuries”.

Thirty-four persons were also killed on the ground after the plane crashed into the hostel building of the BJ Medical College and Hospital in Ahmedabad, according to Air India.

Tone of probe suggests bias towards pilot error, says pilot’s association

The Airline Pilots’ Association of India said that the tone and direction of the investigation suggest “a bias toward pilot error”.

The association said that it was concerned that the preliminary report had been “shared with the media without any responsible official signature or attribution”.

The investigation continues to be “shrouded in secrecy, undermining credibility and public trust”, the association said in a statement, alleging that “qualified, experienced personnel” were not being included in the probe team.

“The report refers to a serviceability bulletin concerning the fuel control switch gates, which indicates a potential equipment malfunction,” the association said. “While the bulletin exists, [the association] demands clarity on whether the recommendations outlined in the bulletin were implemented prior to the flight.”

Also read: Air India crash: What is the Boeing 787 Dreamliner’s safety record? An expert explains