Preliminary report into Air India crash raises questions about fuel control switches

This article has been updated.

India’s Aircraft Accident Investigation Bureau (AAIB) has released its preliminary report into the crash of Air India Flight 171 in Ahmedabad on June 12. The report raises questions about the fuel control switches, which transitioned to cut-off just after lift-off.

Only one of the 242 people on board survived the crash of the Boeing 787-8 Dreamliner, which had been bound for London’s Gatwick airport. Nineteen other people on the ground were killed when the plane crashed into a hostel for medical students.

In its 15-page report, the AAIB states that “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” within seconds of lift-off.

The black box recording indicates that this was not done by either of the pilots.

“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,” the report states.

The report adds: “The Vr speed (155 kts) was achieved as per the EAFR at 08:08:35 UTC. The aircraft air/ground sensors transitioned to air mode, consistent with liftoff at 08:08:39 UTC.”

It continues: “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 Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off.”

The report then refers to the cockpit voice recording in which one pilot asks the other why he cut off the fuel and the other pilot says he did not.

The report then recounts how the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about 08:08:52 UTC. At 08:08:56 UTC, the Engine 2 fuel cutoff switch also transitioned from CUTOFF to RUN.

This indicates an attempt to restart the engines.

The report states that, when fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engine's Full Authority Digital Engine Control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction.

“The EGT [exhaust gas temperature] was observed to be rising for both engines indicating relight," it states.

“Engine 1’s core deceleration stopped, reversed and started to progress to recovery. 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.”

The report says that at about 08:09:05 UTC one of the pilots transmitted a Mayday call and the Enhanced Airborne Flight Recorder (EAFR) recording stopped at 08:09:11 UTC.

An experienced pilot, who would prefer not to be named, told Changing Times: “In normal flight, there is no action done by pilots that early in the take-off phase, not even to raise the landing gear.”

He said that the pilots’ conversation could indicate that the fuel switches moved on their own. “There was possibly a technical issue with the aircraft, i.e., the locking mechanism of the fuel switches was somehow defective.”

Regarding the attempt to restart the engines, he said this was not as easy as starting them on the ground.

“The report mentions that the left-hand engine (engine number 1) began a successful recovery, but the plane crashed before the engine could fully recover. Engine 2, however, had problems with beginning the restart sequence,” the pilot said.

“The pilots made a brave attempt to recover the situation but, because they were too low, this didn't give them enough time to save the situation.”

The pilot makes reference to a Special Airworthiness Information Bulletin (SAIB) issued by the Federal Aviation Administration (FAA) in the US on December 17, 2018, regarding the potential disengagement of the fuel control switch locking feature.

The AAIB report states that the SAIB was issued based on reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged.

“The airworthiness concern was not considered an unsafe condition that would warrant airworthiness directive (AD) by the FAA,” the report states.

“The fuel control switch design, including the locking feature, is similar on various Boeing airplane models including part number 4TL837-3D which is fitted in B787-8 aircraft VT-ANB.

“As per the information from Air India, the suggested inspections were not carried out as the SAIB was advisory and not mandatory.”

The ‘NM-18-33’ SAIB referred to in the AAIB report states: “The fuel control switch has a locking feature to prevent inadvertent operation that could result in unintended switch movement between the fuel supply and fuel cutoff positions. In order to move the switch from one position to the other under the condition where the locking feature is engaged, it is necessary for the pilot to lift the switch up while transitioning the switch position.

“If the locking feature is disengaged, the switch can be moved between the two positions without lifting the switch during transition, and the switch would be exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in an unintended consequence, such as an in-flight engine shutdown.”

In an update to an article by Simon Hradecky on The Aviation Herald website it is stated: “On Jul 11th 2025 a reader made The Aviation Herald aware of a Service Bulletin released by General Electrics (the engine manufacturer) and the FAA: Service Bulletin FAA-2021-0273-0013 ... issued in year 2020/2021, which recommends the replacement of the MN4 microprocessor on the ECU [Electronic Control Unit] with respect to engine fuel and control stating: ‘This recommendation is to address a condition that may affect Flight Safety’.

“The service bulletin further states: ‘Accumulated thermal cycles of the EEC [Electronic Engine Control] with age causes the solder ball to fail’.”

The update adds: “Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 relating to loss of control issue were NOT implemented by Air India.”

The Aviation Herald article adds: “According to discussions in the industry it may be possible with the number of cycles VT-ANB had already completed, the solder balls were weakened sufficiently to detach the MN4 from the EEC momentarily due to loads during the take-off rotation leading to the loss of control of thrust and shut down of the engines.”

The AAIB adds in its preliminary report that fuel samples taken from the bowsers and tanks used to refuel the aircraft were tested at the Directorate General of Civil Aviation lab and were found to be satisfactory. Both the pilots had an adequate rest period before the flight, it said.

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

(The RAT is a small wind turbine deployed as an emergency power source. It generates electricity and/or hydraulic pressure from the airflow created by the aircraft's movement, providing power to critical systems when primary power sources fail.)

“As per the EAFR [Enhanced Airborne Flight Recorder] data both engines’ N2 values passed below minimum idle speed, and the RAT hydraulic pump began supplying hydraulic power at about 08:08:47 UTC,” the report states.

The report adds that no significant bird activity was observed in the vicinity of the flight path.

The aircraft started to lose altitude before crossing the airport perimeter wall, it states.

Given that the AAIB report is only preliminary, it doesn’t draw conclusions or make recommendations. A full report will be issued in due course.

The AAIB states: “This document has been prepared based on the preliminary facts and evidence collected during the investigation. The information is preliminary and subject to change.”

In conclusion, it says: “At this stage of investigation, there are no recommended actions to B787-8 and/or GE GEnx-1B engine operators and manufacturers.

“Investigation is continuing and the investigation team will review and examine additional evidence, records and information that is being sought from the stakeholders.”

In a statement, Air India said: “Air India stands in solidarity with the families and those affected by the AI171 accident. We continue to mourn the loss and are fully committed to providing support during this difficult time. We acknowledge receipt of the preliminary report released by the Aircraft Accident Investigation Bureau (AAIB) today, 12 July 2025.

“Air India is working closely with stakeholders, including regulators. We continue to fully cooperate with the AAIB and other authorities as their investigation progresses.

“Given the active nature of the investigation, we are unable to comment on specific details and refer all such enquiries to the AAIB.”

In its statement in response to the report, Boeing said: “Our thoughts remain with the loved ones of the passengers and crew on board Air India Flight 171, as well as everyone affected on the ground in Ahmedabad. We continue to support the investigation and our customer.”

The Airline Pilots' Association of India (ALPA) issued a statement in which it criticises the investigation, stating that its tone and direction “suggest a bias toward pilot error”.

The association said: “ALPA-I categorically rejects this presumption and insists on a fair, fact-based inquiry.”

It added: “ALPA-I renews its request to be included at the very least, as observers in the investigation process to ensure transparency and accountability.”

The ALPA says the investigations “continue to be shrouded in secrecy, undermining credibility and public trust”. Qualified, experienced personnel especially line pilots are still not being included in the investigation team, it says.

The association notes the reference in the AAIB report to the service bulletin about the fuel control switches and demands clarity on whether the recommendations outlined in the bulletin were implemented prior to the June 12 flight that crashed.

The International Federation of Air Line Pilots' Associations (IFALPA) said: “Whilst this preliminary report by its very nature raises many questions, it does not provide answers, and any extrapolation of its content can only be regarded as guesswork, which is not helpful to the good conduct of the investigation.”

The IFALPA said it again cautioned against “hasty conclusions published by the media and social media based on this report”.

The federation added: “IFALPA urges all parties to refrain from speculation, allow the investigation to run its full and proper course, and avoid drawing conclusions from preliminary information. The victims, including the families of the crew and passengers of Air India 171, deserve our collective professionalism while the full investigation is conducted.”

Just after the AAIB report was released, various online pundits leapt into action to blame the pilots, with two self-appointed experts on YouTube immediately proclaiming “pilot error”.

This is not what is stated or implied in the AAIB report.

The Indian Commercial Pilots' Association (ICPA) said: “We are deeply disturbed by speculative narratives emerging in sections of the media and public discourse – particularly the reckless and unfounded insinuation of pilot suicide.”

The association added: “Let us be unequivocally clear: there is absolutely no basis for such a claim at this stage, and invoking such a serious allegation based on incomplete or preliminary information is not only irresponsible – it is deeply insensitive to the individuals and families involved.”

To casually suggest pilot suicide in the absence of verified evidence was “a gross violation of ethical reporting and a disservice to the dignity of the profession”, the association said.

“Until the official investigation is concluded and the final report is published, any speculation – especially of such a grave nature – is unacceptable and must be condemned,” it added.

The association called upon media organisations and public commentators “to act with restraint, empathy, and respect for due process”.

It said the crew of AI 171 acted in line with their training and responsibilities under challenging conditions and deserved support, “not vilification based on conjecture”.

The Indian Pilots’ Guild (IPG) echoed the ICPA’s call for “restraint, empathy, and respect for due process”.

It said that aviation safety depended on transparency and accuracy, not assumptions.

“Let us be clear: premature conclusions based on half-verified data are irresponsible. They harm reputations, delay real safety lessons, and distract from the pursuit of truth,” the IPG said.

“The crew of AI 171 deserves a thorough, fact-driven investigation – not conjecture or sensationalism.”

The IPG expressed “deep concern” over the AAIB’s preliminary report.

“While we acknowledge the complexities of ongoing investigations, we find the current report incomplete in critical areas – specifically the unexplained dual engine shutdown and absence of detailed cockpit communication,” the guild said.

“A report that omits vital technical explanations and cockpit voice transcripts opens the door to unnecessary speculation and misinformed narratives in the media. Such omissions not only erode public trust but also risk unjustly undermining the professionalism and conduct of the flight crew involved.”

The IPG urged investigative bodies “to deliver a complete, conclusive, and technically sound report in the spirit of accountability and truth”.

In a statement issued on July 16, the Federation of Indian Pilots (FIP) expressed “serious concern” regarding the preliminary findings and public discourse surrounding the Al 171 crash.

The federation said it wished to register its dissatisfaction with the exclusion of pilot representatives from the investigation process and firmly objected to the way in which the preliminary report had been interpreted and presented publicly.

“The report, as released, lacks comprehensive data and appears to rely selectively on paraphrased cockpit voice recordings to suggest pilot error and question the professional competence and integrity of the flight crew,” the FIP said.

“This approach is neither objective nor complete. We therefore urge our members and the general public not to lend credence to such premature conclusions.”

Assigning blame before a thorough, transparent, and data-driven investigation was both premature and irresponsible, the FIP said.

“Such speculative commentary undermines the professionalism of highly trained crew members and causes undue distress to their families and colleagues,” it added.

The FIP urged all stakeholders, including the media, commentators, and authorities, “to refrain from disseminating partial narratives or making unfounded assumptions”.

Aviation safety, the federation said, demanded “a steadfast commitment to facts, integrity, and due process”.

The FIP reiterated its call for “a fair, transparent and evidence-based investigation before any definitive conclusions are drawn”.

India’s Aircraft Accident Investigation Bureau (AAIB) issued an appeal on July 17 stating that is was essential to respect the sensitivity of the loss faced by family members of deceased passengers, crew of the aircraft, and other deceased persons on the ground.

“It has come to our attention that certain sections of the international media are repeatedly attempting to draw conclusions through selective and unverified reporting,” the AAIB said.

“Such actions are irresponsible, especially while the investigation remains ongoing. We urge both the public and the media to refrain from spreading premature narratives that risk undermining the integrity of the investigative process.”

The bureau added: “The purpose of the AAIB's investigation and preliminary report is to provide information about 'WHAT' happened. The preliminary report has to be seen in this light.”

At this stage, the AAIB said, it was too early to reach any definite conclusions. The investigation by the AAIB was still not complete and the final investigation report would come out with root causes and recommendations.

The AAIB appealed to all concerned to await publication of the final report after completion of the investigation and said it would publish updates as and when required that had technical and public interest.

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