Air India crash probe: What we know so far about the fatal Boeing 787 accident

Mystery of why aircraft's fuel control switches were turned off remains unsolved, but theories abound

Wreckage of the Air India Boeing 787-8 Dreamliner. Reuters

A preliminary report on the investigation into the Air India flight that crashed last month has answered some questions about the fatal accident but raised many more and fuelled speculation about the cause.

India's Aircraft Accident Investigation Bureau released the report on July 12, shedding some light on the tragic crash of Air India Flight AI 171.

But it has also led to debate about the role of the pilots, the flow of fuel to the plane's engines and the merits of installing cockpit cameras to help aviation safety authorities in their investigations.

So what do we know so far about the accident and the shockwaves it has sent through the aviation industry?

Sole survivor of Air India plane crash recounts moment aircraft came down

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What happened?

The Air India aircraft – a Boeing 787-8 Dreamliner – crashed shortly after taking off from Ahmedabad Airport, in Gujarat, north-west India, on June 12.

The London Gatwick-bound flight, which was carrying 230 passengers and 12 crew members, crashed into buildings of a medical college near the airport. The accident killed 260 people − all the crew, all but one of the passengers and 19 people on the ground.

The aircraft, registration VT-ANB, was fitted with GE engines.

What is the cause of the crash?

The 15-page preliminary report released by the AAIB suggested that the aircraft's fuel control switches were turned off, cutting fuel to the engines and causing a loss of engine thrust shortly after take-off.

Fuel control switches regulate fuel flow into an aircraft's engines, used by pilots to start or shut down engines on the ground or to manually shut down or restart engines, if an engine failure occurs during a flight.

“In the cockpit voice recording, one of the pilots is heard asking the other why did he cut off. 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 had been flipped back to the run position, the report said, but the plane could not gain power quickly enough to avoid crashing.

The report findings left a key question unanswered: Why and by which pilot were two fuel switches moved to a cut-off position, starving the two engines of thrust just as the plane needed the most lift.

The report is based on data from the aircraft's black boxes, which combines digital flight data and cockpit voice information.

Can theories by substantiated?

In a statement on July 17, the AAIB said that it is “too early to reach any definitive conclusions” about the cause of the crash.

“The investigation by the AAIB is still not complete. The final investigation report will come out with root causes and recommendations,” it said.

The body urged the public and the media to refrain from “spreading premature narratives” that risk undermining the integrity of the investigative process.

It added that “certain sections of the international media are repeatedly attempting to draw conclusions through selective and unverified reporting.”

This came after media reports abounded about the role of one of the pilots in cutting the flow of fuel to the plane's engines, but these have not been substantiated by official findings.

When will the final report come out?

The AAIB said on July 17 that it will publish updates “as and when required”.

“AAIB appeals to all concerned to await publication of Final Investigation Report after completion of the investigation. AAIB will also publish updates, as and when required, which have technical and public interest,” the body said in a statement, without providing a date for the final report.

What have Boeing said so far?

The Air India crash marks the first hull loss for Boeing's 787 widebody aircraft.

Boeing has said it continues to support the investigation.

The accident will be a “stress test” for Boeing, which had made progress in rebuilding trust after a series of safety and production quality lapses, analysts have said.

“At this stage of investigation, there are no recommended actions to 787-8 and/or GE GEnx-1B engine operators and manufacturers,” according to the AAIB report.

Willie Walsh, director general of the International Air Transport Association, said earlier this week that there is a “strong argument” to install cockpit cameras that would help aviation safety authorities investigating accidents such as the Air India crash, Bloomberg reported.

What has Air India done in response to the accident?

India's civil aviation regulator ordered the country's airlines this week to investigate the locking feature on the fuel switches of several Boeing models.

Air India's inspection of the locking feature on the fuel control switches of its existing Boeing 787 aircraft found no issues, AFP reported, citing an internal airline memo.

What are other Boeing 737 and 787 operators doing?

Flydubai has joined several other airlines in the Middle East in checking the cockpit fuel switches on their Boeing aircraft, following the Air India crash investigation report.

Flydubai conducted “precautionary inspections” of the fuel switches on its Boeing 737.

Elsewhere in the region, Saudia said it had completed precautionary inspections on the fuel shut-off switch system across its 787 fleet and that “all aircraft remain fully operational.”

Oman Air said it has finished checks on its 787s and is completing inspections of its 737s.

When will Air India resume normal flight schedules?

Air India on July 15 said it had performed additional precautionary checks on its Boeing 787 aircraft and would partially restore its international flight schedule, which it had scaled back after the crash.

It will resume some flight frequencies from August 1, with full restoration planned from October 1.

With the partial restoration, Air India will operate more than 525 international flights per week on 63 short, long and ultra long-haul routes.