One year after the Air India crash, what still remains unanswered?

A year after Air India Flight AI171 crashed moments after departing Ahmedabad for London, investigators are still working to answer the question that has dominated the inquiry since June 12, 2025: why did both engines on a Boeing 787 Dreamliner lose fuel within seconds of take-off?

The tragedy, which killed 260 people, remains one of the most closely scrutinised aviation accidents in recent history.

It was the deadliest air disaster globally in a decade and the first fatal crash involving Boeing's 787 Dreamliner since the aircraft entered commercial service in 2011.

As the first anniversary of the disaster arrives, India's Aircraft Accident Investigation Bureau (AAIB) has yet to release its final conclusions.

Sources familiar with the probe indicated to Reuters that investigators require additional time to complete technical assessments involving the aircraft's engines and associated systems.

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The delay means that while investigators have established a detailed sequence of events during the aircraft's final moments, the underlying cause behind those events remains unresolved.

A disaster that shocked the world

The aircraft involved was a Boeing 787-8 Dreamliner operating as Air India Flight AI171 from Ahmedabad to London's Gatwick Airport. On board were 242 people. Only one passenger survived.

The aircraft crashed into a hostel complex near Ahmedabad airport, causing fatalities both inside the aircraft and on the ground. In total, 260 people lost their lives, including 241 of the 242 occupants of the aircraft and 19 people on the ground.

The crash occurred at a particularly sensitive moment for Air India. The airline was in the midst of a major transformation programme following its privatisation.

Efforts to modernise operations and rebuild the carrier had already been challenged by global supply-chain disruptions, restrictions resulting from Pakistan's airspace ban on Indian airlines, and now ongoing tensions tensions linked to the US-Israeli war on Iran.

Why investigators are still not ready with a final report

International aviation standards encourage accident investigators to publish a final report within one year of a crash whenever possible.

However, the rules also recognise that complex investigations can require additional time. In such cases, authorities are expected to provide updates on the anniversary of the accident while continuing their work.

According to people familiar with the investigation, Indian authorities are expected to miss the one-year target because critical technical examinations remain incomplete.

Reuters reported last month that officials were preparing an interim report rather than a final document because the inquiry remained highly complex and time-consuming. At the time, a source indicated that no decision had been taken regarding when the final report would be completed.

Subsequently, Bloomberg reported that investigators expected to conclude the probe within several months after ongoing engine studies are completed.

The continuing analysis has centred largely on the aircraft's GE Aerospace engines.

Sources familiar with the matter told Reuters that investigators carried out engine-related testing in April and travelled to France during May as part of a broader examination of the engine management unit. Components from the aircraft's engines have also been sent to the United States for detailed analysis.

These continuing technical reviews are among the principal reasons the final report has not yet been issued.

Neither the AAIB, India's aviation ministry, Air India, Boeing, GE Aerospace nor the US National Transportation Safety Board immediately commented on the latest reports regarding the timing of the final report.

What the preliminary investigation established and did not

Although investigators have not determined the ultimate cause of the accident, they have reconstructed much of what happened during the final moments of the flight.

The AAIB's preliminary report, published on July 12, 2025, identified a crucial event that occurred seconds after take-off.

According to investigators, both engine fuel-control switches moved from the "RUN" position to the "CUTOFF" position shortly after the aircraft became airborne.

The movement of those switches interrupted the flow of fuel to both engines. As a result, thrust began decreasing almost immediately.

The aircraft rapidly lost the power necessary to maintain flight and began descending. Investigators determined that the switches were later returned to the "RUN" position and that efforts were made to restart the engines. However, the aircraft did not have sufficient altitude or time to recover before impact.

The preliminary findings established what happened inside the cockpit.

What they did not establish was why it happened. That distinction remains at the centre of the investigation one year later.

The final nine minutes before departure

The preliminary report provides a highly detailed chronology of the aircraft's final movements. Earlier that morning, the aircraft, registered VT-ANB, had completed a flight from New Delhi to Ahmedabad while operating as Air India Flight AI423.

At 05:47 GMT, the aircraft landed in Ahmedabad. Roughly two hours later, preparations began for the scheduled departure to London.

At 07:48:38 GMT, the aircraft was observed leaving Bay 34. At 07:55:15 GMT, the crew requested taxi clearance, which air traffic control approved.

The aircraft then proceeded toward Runway 23 using Taxiway R4 before positioning itself for departure. At 08:02:03 GMT, responsibility for controlling the aircraft was transferred from ground control to tower control.

Take-off clearance was issued at 08:07:33 GMT. Four seconds later, the aircraft began its take-off roll.

At 08:08:39 GMT, the Dreamliner lifted off the runway. According to investigators, the aircraft's air-ground sensors switched to airborne mode as expected following lift-off.

Up to that point, the departure appeared routine. Within seconds, however, the situation changed dramatically.

The crucial seconds after take-off

The AAIB timeline shows that at 08:08:42 GMT, approximately three seconds after becoming airborne, the aircraft reached a maximum recorded airspeed of 180 knots.

Immediately afterwards, investigators recorded a change in the positions of the fuel-control switches.

According to the report, "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 added, "The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off."

The cockpit voice recorder captured a brief exchange between the pilots during this period.

The 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." Meanwhile, airport CCTV footage documented another significant development.

"The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off."

Investigators noted, "The aircraft started to lose altitude before crossing the airport perimeter wall."

At 08:08:47 GMT, both engines dropped below minimum idle speed. The RAT hydraulic pump began providing hydraulic power. Five seconds later, at 08:08:52 GMT, one of the fuel-control switches was moved back from "CUTOFF" to "RUN".

Four seconds after that, the second switch was also restored to the "RUN" position.

Investigators explained the significance of this action, "When fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction."

The report indicates that Engine 1 began showing signs of recovery.

"Engine 1's core deceleration stopped, reversed and started to progress to recovery." Engine 2 also relit but struggled to regain sufficient performance.

"Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery."

At 08:09:05 GMT, one of the pilots issued a distress call:

"MAYDAY MAYDAY MAYDAY".

Six seconds later, flight data recording ended. At 08:14:44 GMT, airport firefighting vehicles departed the airport to begin rescue and firefighting operations.

The big question: deliberate action, error or malfunction?

One year after the crash, virtually all debate surrounding Flight AI171 centres on a single issue.

What caused the fuel-control switches to move? Investigators, aviation specialists and pilot representatives have examined several possibilities.

One theory being considered is whether the switches were moved deliberately by a pilot.

Reuters reported last year that a cockpit recording reviewed by US officials formed part of an early assessment suggesting the captain may have interrupted fuel flow to the engines.

The pilots operating the aircraft were Captain Sumeet Sabharwal and First Officer Clive Kunder. Sabharwal, aged 56, had accumulated more than 15,600 flying hours, including over 8,500 hours on Boeing 787 aircraft.

Kunder, aged 32, had logged more than 3,400 flying hours after joining Air India in 2017.

Both possessed the certifications required to operate the aircraft. The theory has attracted attention because the fuel-control switches are designed with safeguards intended to prevent accidental movement.

Some aviation experts have argued that moving both switches within such a short timeframe would ordinarily require a deliberate action. However, investigators have repeatedly warned against drawing conclusions before all evidence has been examined.

The AAIB previously stated it was "too early to reach any definite conclusions."

In February 2026, the agency publicly criticised speculative reporting and reiterated that the investigation remained active. No official investigation report has concluded that the crash resulted from intentional action by either pilot.

Pilot groups reject early conclusions Pilot organisations have strongly opposed suggestions that the crew may have caused the crash.

Among the most vocal critics has been the Federation of Indian Pilots. The organisation has argued that investigators should exhaust every possible technical explanation before assigning responsibility to the flight crew.

Ahead of the anniversary, the federation renewed those concerns. Its leadership also objected to the possibility of authorities issuing an interim report before the investigation is complete.

Speaking in Ahmedabad, federation president Captain CS Randhawa said, "It will cause more speculation and more misunderstanding."

"We have requested the Indian government and India's Aircraft Accident Investigation Bureau (AAIB) not to come out with any interim report."

The federation has additionally urged investigators to obtain more technical information from Boeing and Air India, arguing that further evidence is necessary to allow for a "rebuttal of the pilot suicide theory being explored by the AAIB".

Randhawa also claimed there were deficiencies in the preliminary report and asserted that the aircraft had experienced several technical issues before departure.

According to him, the aircraft arrived from Delhi with a stabiliser-related problem, prompting replacement of motors before the aircraft was cleared for service.

He also alleged that electrical issues affected air-conditioning and other systems onboard.

The federation has also questioned aspects of the timeline contained in the preliminary report. Regarding the cockpit voice recorder evidence, Randhawa argued that only a very short portion of the recording had become the focus of public discussion, stating that "Western media picked it up as a deliberate attempt".

Could a technical problem still be responsible?

Another possibility being examined is the existence of a technical malfunction.

Some independent aviation experts have suggested investigators should continue examining whether a software anomaly, electronic fault, systems malfunction or other technical issue could have influenced the movement of the fuel-control switches or generated misleading information inside the cockpit.

Others have pointed to the aircraft's maintenance history as an area requiring continued scrutiny.

However, investigators have not publicly identified evidence showing that a design flaw in the Boeing 787 or a defect in the GE Aerospace engines caused the accident. Regulators in India and the United States have not grounded the Dreamliner fleet following the crash.

The AAIB's preliminary report also did not recommend safety actions directed at Boeing or GE Aerospace, a sign that investigators had not identified a specific technical deficiency requiring immediate intervention at that stage.

Families continue to seek answers

For relatives of the victims, the debate surrounding pilot actions, technical failures and investigative theories remains secondary to obtaining a definitive explanation.

Families of those who died, along with sole survivor Vishwashkumar Ramesh, have repeatedly called for transparency and clarity regarding the events that unfolded inside the cockpit.

Their demand has remained unchanged throughout the past year: determine exactly why both engines lost fuel moments after take-off and identify any lessons necessary to prevent a similar disaster in the future.

One year after the crash, investigators agree on a critical fact. The Boeing 787 lost thrust after both engines were deprived of fuel when the cockpit fuel-control switches moved from "RUN" to "CUTOFF" seconds after lift-off.

What remains unknown is whether that movement resulted from deliberate action, inadvertent human error, a technical malfunction or another factor that has yet to be identified.

With inputs from agencies