Flight AI-171: An investigation or a cover-up?

On 12 July, at the unearthly hour of 1.00 am, the Aircraft Accident Investigation Bureau (AAIB) released its preliminary report on the crash of Air India Flight AI-171. There was no press conference, no media briefing, no effort to contextualise the findings or address public concerns about safety. A quiet upload of a 15-page document on a government portal was deemed enough.

As mandated, the report appeared exactly a month after the crash, which killed 241 people on board the Boeing 787-8 Dreamliner and 19 on the ground, barely 32 seconds after the London-bound flight took off from Ahmedabad. Instead of clearing the fog, the details it includes — and omits — has only deepened the mystery surrounding the country’s most serious aviation disaster in recent memory.

One of the most glaring omissions was reported by the Indian Express (17 July), quoting an unnamed official who said: ‘Just hours before take-off from Ahmedabad to London Gatwick on 12 June, a pilot flying the same aircraft from Delhi to Ahmedabad noted in the technical log a “Stabilizer Position Transducer Defect”’ — a critical fault in the sensor that controls the aircraft’s pitch and transmits vital signals to the flight control system.

Though maintenance engineers addressed the issue following Boeing’s standard procedures, officials have flagged it as significant, warning that such a malfunction can interfere with flight control responses and potentially trigger unintended commands, such as fuel cutoff.

Additional entries in the technical logs include an electrical snag that led to a flight cancellation and a separate instance of a false fuel system warning. Investigators are now scrutinising these records to trace a possible pattern of sensor- or software-related vulnerabilities.

Should these vital points not have been recorded in the preliminary report?

In aviation, transparency is as essential as airspeed. While the AAIB has technically complied with the norms of the International Civil Aviation Organization’s (ICAO) Annex 13 — which requires a preliminary report within 30 days of an accident — critics say it has failed to follow the rules in spirit. ICAO recommends that preliminary findings, especially in high-fatality crashes, be accompanied by public communication to avoid speculative narratives. This report, delivered in silence, has triggered just that.

“The preliminary report raises more questions than answers,” says aviation veteran Shakti Lumba, former head of operations at IndiGo. Giving a clean chit to Boeing, Air India and General Electric in the preliminary report “sours the whole investigation”. Especially since the report only cursorily mentions the Service Bulletin (SB) on the fuel switches — issued by the US FAA (Federal Aviation Administration) — which was, for all practical purposes, ignored by both regulators and airlines. “Any airline prioritising safety would have carried out the checks prescribed by the FAA, no matter what,” Lumba adds sharply.

He also points out that India has had a long-standing tradition of ordering a judicial court of inquiry after major civil air disasters. Concerned that the current probe appears biased in favour of Boeing and GE, he feels such a court of inquiry is indeed necessary.

Rajya Sabha MP Priyanka Chaturvedi voiced outrage at reports that foreign media had access to the findings before they were made available to domestic outlets. The International Federation of Air Line Pilots’ Associations (IFALPA) also issued a rare public statement, warning against premature conclusions and urging investigators to safeguard against speculative interference.

In themselves, the preliminary findings are startling. The report maintains that after take-off, Flight AI-171 accelerated normally, reaching 180 knots — the takeoff speed — at 13:38:42 IST. Almost immediately after this, both the fuel control switches transitioned from ‘RUN’ to ‘CUTOFF’ position. Starved of fuel, both engines lost power within seconds.

“The fuel control switches did move,” he adds. “What we don’t know is why. Until we do, speculation is premature — and answers are necessary.” Rudy says it could take up to two years before a comprehensive final report is released.

Central to this line of inquiry is the role of the Boeing 787’s fuel control architecture. FADEC is an advanced engine management system that regulates fuel flow, throttle commands and numerous other performance parameters. But its sophistication comes with a caveat — it logs electrical signals, not mechanical movements. If the switches were manually flipped, or if a false electrical command was issued due to a glitch, FADEC would record the data.

As Capt. Amit Singh, a seasoned aviation safety expert, notes: “In aviation, ‘command issued’ does not always mean ‘switch moved’. FADEC doesn’t confirm intent — it only logs response.”

Further complicating matters is the aircraft’s Throttle Control Module (TCM), which houses the switches. Sources within Air India have confirmed to PTI that this module was replaced twice — once in 2019 and again in 2023 — following Boeing-issued service bulletins. While the replacements were not prompted by fuel switch malfunctions, in retrospect, their timing seems significant.

In 2018, the FAA had flagged potential vulnerabilities in the locking mechanisms of fuel switches across Boeing aircraft, including those with similar configurations to the 787. The bulletin, however, was non-mandatory, and there is no record of Air India having acted on it. Boeing has since maintained that the design remains safe. The FAA, too, has stated that there is no current indication of an unsafe condition. With 260 lives lost, these assurances offer little comfort.

Aviation professionals are divided — some suggest cockpit ergonomics may have played a role, others blame software or electronic signal corruption.

Pilot unions, including IFALPA, have urged investigators not to draw premature conclusions about the crew. The design of the switches, and FADEC’s inability to distinguish between intent and command, are now under international scrutiny.

The Ram Air Turbine (RAT) and Auxiliary Power Unit (APU) were deployed. The cockpit crew attempted to restart the engines — one engine partially reignited. Just 1.5 km from the runway, the aircraft crashed — barely 32 seconds into its flight. There were no indications of weather disturbance, bird strike, mechanical failure or weight imbalance. And yet, both engines shut down. The cause? No one knows.

A short exchange captured on the Cockpit Voice Recorder (CVR) has added to the fog: ‘One of the pilots is heard asking the other why he cut off the switch. The other pilot responded that he did not do so.’

No speaker is identified; no source microphone is specified; it’s not clear if the first speaker was the captain or the co-pilot. The ambiguity of this snippet leaves it open to all sorts of interpretations — including the reckless and insensitive suggestion that one of the two pilots was suicidal. Had the first speaker seen the second switching it off? It is not clear. Assuming it was deliberate, why would he deny it?

The report also mentions that the pilots tried to restart the engines, but by the time one of them reignited, it was too late. Doesn’t that rule out the ‘suicide theory’? Is it possible that the pilots desperately tried to switch it back to ‘Run’? The switches are designed to make a distinct ‘click’ when toggled, but the preliminary report claims that sound is missing from the audio. Was there human intervention? Was it inadvertent? Or was it a systemic fault that triggered the command? No one knows.

Rajiv Pratap Rudy, the BJP’s Lok Sabha MP from Saran in Bihar and a trained commercial pilot, says accountability must also extend to aircraft manufacturers and global regulators. He asks why earlier advisories issued by the FAA — specifically those highlighting potential vulnerabilities in the fuel switch locking mechanisms — were not acted upon more decisively. Could the aircraft’s Full Authority Digital Engine Control (FADEC) system be susceptible to erroneous shutdown signals?

So far, neither Boeing nor any regulator has suggested fleet-wide grounding of the 787 Dreamliner, though some operators have begun precautionary checks of fuel switch assemblies. The Directorate General of Civil Aviation (DGCA) issued directives to Indian operators only after Etihad, Singapore Airlines and Korean Air had taken such steps.

Meanwhile, engine malfunctions continue to trouble airlines operating in India — occurring at an average of one incident per month, affecting a variety of aircraft types. According to a response provided by the DGCA to an RTI query by the Times of India, a total of 65 incidents involving in-flight engine shutdowns have been reported across the country between 2020 and 2025 (till date).

In each of these cases, pilots successfully diverted the aircraft to the nearest airport, relying on the unaffected engine. Whether under investigation or concluded, none of them are available in the public domain. The DGCA data further reveals that between 1 January 2024 and 31 May 2025, 11 flights issued ‘Mayday!’ calls, citing various technical faults and requesting emergency landings. Notably, this figure does not include AI-171, nor the IndiGo domestic flight diverted on 19 June due to a technical issue.

Confidence in air travel is built not just on machinery and engineering, but on faith in the institutions that investigate and respond to failure. With the skies still filled with 1,148 Dreamliners (32 with Air India), the world is watching how India, Boeing and the global aviation community navigate the path ahead.

There is no room for obfuscation — only full transparency, swift accountability and a determined pursuit of truth. Until the final report is released, all possibilities remain on the table — pilot error, mechanical malfunction, a FADEC system failure, issues with the locking mechanisms.

The AAIB preliminary report on the AI-171 incident stands as a case study in silence: a tragedy shaped by 32 seconds, two switches and a lingering trail of unanswered questions.