Was pilot action to blame for Air India Ahmedabad crash? Here’s what we know so far

Experts suggest that it is next to impossible for these switches to have moved on their own or by accident.

Union Minister of State for Civil Aviation and Cooperation Murlidhar Mohol has said that the report is not yet final, and the information is “still under the purview of investigation”.

Here’s a breakdown of what might have happened, and how.

Both engines ‘failed’

Experts have long believed that the crash was caused due to both engines ‘failing’ during the critical take-off phase. This conclusion is borne out of three key facts.

* The aircraft had barely taken off before it began to lose altitude: it “started to lose altitude before crossing the airport perimeter wall,” AAIB’s report says. The Boeing-787 is designed to be fully operational at all phases of flight on one engine alone: such a rapid loss of altitude indicates both engines had major trouble.

* Footage of the ill-fated aircraft showed that its Ram Air Turbine (RAT) was deployed very shortly after lift-off. RAT is a small wind-turbine that acts as an emergency power source: it is only activated in case both engines are lost, and is meant to provide electrical and hydraulic power for critical operations.

* If only one engine had failed, the aircraft would have swerved to the other side before the plane’s computer would make appropriate corrections. This did not happen, indicating both engines lost thrust at the same time.

Behind double-engine ‘failure’

The question then is what led to both engines losing power at the same time. Modern aircraft engines are extremely reliable, meaning a double-engine failure is not just rare but also very difficult to explain.

* One possible cause being discussed in the aftermath of the crash was fuel contamination. However, this would likely have been spotted during the pilots’ pre-flight routine. Furthermore, the preliminary report states that “samples taken from the bowsers and tanks used to refuel the aircraft were tested… and found satisfactory”.

* Catastrophic bird strikes (re: “Miracle on the Hudson” in 2009) too could be a plausible, although improbable, explanation. That said, modern jet engines are capable of withstanding a lot of bird damage, and the AAIB report states: “No significant bird activity is observed in the vicinity of the flight path.”

* Pilot error is the third possible explanation for the loss of two engines. An incorrect input of flight parameters before takeoff could have caused the failure, as could have, as the preliminary report suggests, cutting off the fuel supply to the engines.

“The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec,” the report states.

An inexplicable action

As such, these switches controlling the flow of fuel into the engines are put in the “cutoff” position only while the aircraft is on the ground, or in emergency situations such as an engine fire while at a high altitude. There is no official protocol for this action during takeoff, even in case of an engine fire. The aircraft must be at a pre-determined safe altitude before such an action is taken.

Moreover, it is next to impossible to accidentally move the switches to the cutoff position. Not only are there brackets — basically, raised surfaces — to prevent accident handling, since the 1950s, fuel control switches have come with a standard stop-lock mechanism: they must be pulled up to unlock before being flipped.

“It would be almost impossible to pull both switches with a single movement of one hand, and this makes accidental deployment unlikely,” a Canada-based air accidents investigator told the BBC.

There also seems to have been some confusion about these switches being flipped in the cockpit. The preliminary report states: “In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so.”

Note that both fuel control switches were found in the “run” position in the wreckage, and the AAIB report indicates both engines were relit in-flight but could not help the aircraft recover at a low altitude.

More questions than answers

The preliminary report provides seemingly concrete answers for the “what” and “how” questions around the crash that killed 260 people (241 on board and 19 on the ground). But it does not answer the “why” of the question: why would a pilot cut fuel off to both engines, especially at such a low altitude?

Both pilots were experienced operators, with a flying experience of more than 9,500 hours on the specific aircraft. They also passed breathalyzer tests in the morning, and were deemed fit to fly.

Peter Goelz, a former managing director of the US’s NTSB, told the BBC: “The finding is very disturbing — that a pilot has shut off the fuel switch within seconds of flying.” According to him, “There’s likely much more on the cockpit voice recorder than what’s been shared. A lone remark like ‘why did you cut off the switches’ isn’t enough.” The transcript of the conversation has not been released yet.

The preliminary AAIB report states that the United States’ Federal Aviation Authority in 2018 had flagged the potential issue with the “disengagement of the fuel control switch locking feature” in Boeing-737s, adding that this “was not considered an unsafe condition”. As such, experts say that this is unlikely to have been a major problem. The AAIB report says that the throttle control module, which contained the fuel switches, were replaced in 2019 and 2023.

Which once again brings the spotlight on pilot action. Some have speculated that the aircraft might have lost one engine, which the pilots misidentified, and ended up shutting the wrong engine. Even if this were to be the case, however, it would not explain pilots not following the standard, methodical procedure for cutting an engine off.