Air India crash report: Unanswered questions, and some reading between the lines

Most preliminary air accident investigation reports in the past have been a compilation of basic facts, mostly detailing ‘what happened’ more than the ‘why it happened’. This particular report marks a departure from the normal in providing more details of what led to the crash, but limits the information on the most crucial exchange that took place in the cockpit to just that one line and a really brief response.

Both switches are documented as transitioning back to ‘RUN’ after the exchange between the pilots captured in the report. Generally, when the CVR is played, the room has colleagues of the pilots who’ve worked with both of them so that their voices can be identified in exchanges. In all probability, that exercise would have already been done. The recording data should also be able to identify the individual headset microphones of the two pilots. The report, however, stops short of identifying which of the two pilots asked the question in the cockpit, and who answered.

The fully-labelled cockpit voice recorder transcript, which could be released in the final report, should be able to reveal which of the two pilots tried to restart the engines—co-pilot Clive Kunder (pilot flying) or pilot-in-command Sumeet Sabharwal (pilot monitoring). Experts believe that only the full audio and transcript of the cockpit voice recorder recording would be able to shed light on the pilots’ discussions and actions in the cockpit in the minutes leading up to the tragedy. The recording must also be correlated with the flight data from the flight recorders.

The Ahmedabad crash could also underline the need for cockpit video recorders, experts said. The US NTSB is among agencies that have been recommending the need for video recorders in the cockpit for years, only to be met with strong resistance from pilot unions. A video would have given a clear view of the instrument console over the shoulders of the pilots, which would have helped establish if any crucial switches were moved when they weren’t supposed to be touched, and if so, by whom.

Aviation psychologist in the probe team

The preliminary report from the investigation, led by the AAIB, had experts from Boeing, General Electric, Air India, Indian regulators other than the AAIB, and participants from the US, the UK and Canada. Alongside “experienced pilots, engineers, aviation medicine specialists…and Flight Recorder Specialists”, who have been taken on board as subject matter experts to assist the investigation, there is one interesting addition: an aviation psychologist.

Given the circumstances of the crash, an aviation psychologist could have been drafted to peruse human factors like stress, fatigue, quality of communication between the pilots, and indications of their alertness and decision-making. In this particular case, given the indication that both the fuel control switches transitioned to CUTOFF position in quick succession, the psychologist could help analyse any human involvement that might have been there. It is not clear whether the inclusion of the aviation psychologist in the initial probe was to cover all bases, or to look into any specific aspect.

Aviation psychologists are learnt to have played a big role in the Germanwings Flight 9525 crash enroute from Barcelona–El Prat Airport in Spain to Düsseldorf Airport in Germany in 2015.

Families of victims of the Air India plane crash at the DNA testing centre in Ahmedabad. (Express Photo: Bhupendra Rana)

Relevance of FAA advisory on ‘potential disengagement’ of switch locking feature

The AAIB report does make a specific reference to a December 2018 US Federal Aviation Administration issued Special Airworthiness Information Bulletin (SAIB) highlighting that some Boeing 737 fuel control switches were installed with the locking feature disengaged. The same switch design is used in Boeing 787-8 aircraft, including Air India’s AI 171 that crashed. It goes on to say the SAIB was advisory and not a directive, and that Air India did not perform the advised inspections as they were not mandatory.

Notably, the cockpit’s throttle control module — which is integrated with the fuel control switches — was replaced in 2019 and 2023, but the reason for replacement was not linked to the switches. The initial report said that no defect pertaining to the fuel control switches on the aircraft was reported since 2023. If that is the case, then why did the initial probe report include this specific SAIB? Was it in the spirit of maximum disclosure while suggesting the issue was not really relevant to this particular aircraft? It is not clear.

If there indeed was a problem with the fuel control switches’ locking mechanism, does it imply that the spring-loaded switch could be moved with just a single flick, instead of being pulled up first and then moved from one mode to the other, which is how it is normally operated? Was there any possibility of the switch, if the locking mechanism was disengaged, just flipping on its own and shutting down the engine? That really is not clear.

The report nowhere clearly states that the fuel control switches were indeed moved by either of the pilots during take-off. It just says that they “transitioned” from RUN to CUTOFF based on the black box data. Some pilots and experts have said that the investigators must also closely examine the possibility of an electrical or software malfunction signalling to the aircraft system that the switches were in cut-off mode without being physically moved.

The fact that the preliminary report has not issued any recommendation to the operators of the Boeing 787 aircraft and the GE GEnx-1B engines suggests that the investigators, at least for the time being, do not have sufficient reason to believe that an electrical or system malfunction could have led to the fuel control switches “transitioning” to CUTOFF.

It is worth noting that the preliminary report is only an account of the initial findings of the investigation, and is subject to change on the basis of the progress of the probe over the coming months. Aircraft are extremely sophisticated and complex machines, and detailed and painstaking investigations are required to ascertain the exact cause or combination of causes. The odds that an aviation accident has a single trigger are rare, and crashes usually have a series of things that go wrong together or one leading to another. The AAIB is expected to release the final probe report within a year of the crash, as per international guidelines.