Roshomon effect: AAIB's prelim report teases some info, holds back key details, and opens scope for varying interpretations till final report is in

Indian Express

7 days ago

A preliminary investigation report into an aircraft accident is generally just that: an initial status report that details the circumstances of the crash and presents bare facts known in the early stage of the probe. This particular 15-page preliminary report on the AI 171 crash goes beyond the mandate by giving some additional details, but selectively. Without the proper context, necessary elaboration, and disclosure of related information, it has lent itself to a great deal of ambiguity by the way details have been worded. Unsurprisingly, there seem to be more questions than answers, and the level of speculation on the causes of the accident—which was expected to moderate after the report's release—has only gone several notches higher. As one expert put it: the report says a lot, but reveals little, and fuels confusion.
There has been no serious attempt on the part of the Aircraft Accident Investigation Bureau (AAIB) before or after the report—uploaded on the AAIB website in the middle of the night—to clarify on genuine and technical questions being raised by experts and explain the evident gaps in information that the report contains. Ever since the crash occurred, official information on the investigation's progress has been scarce, leading to wild speculation on social media and even news media. The Ministry of Civil Aviation (MoCA) has so far held just one briefing on the accident—on June 14, two days after the crash—where no questions were taken. Prior to the release of the official preliminary report, there were just a few press releases on the status of the probe, with no real information on the findings.
In the absence of a regular flow of official information, an information vacuum has been created, which is being filled by wild speculation, misinformation, and even fake news. Add to that an abstruse initial probe. All this is leading to a lot of conjecture and largely uninformed finger-pointing. The dead pilots, Air India, Boeing, GE; pick your target. All this stokes a kind of Rashomon effect — the same data and events being interpreted in multiple different ways, depending on who is reviewing it.
No time stamp
The one statement captured as a paraphrased exchange between the pilots has been presented without full context, in a paraphrased manner, and without timestamps does beg the question: was it relevant to put just this one line out, instead of the full transcript, which the investigators surely have in their possession? From the cockpit voice recorder (CVR) data, the report states that one of the pilots asked the other why he cut off the fuel, to which the other pilot responded saying he did not. But what was said before and after that is conspicuous by its absence in the report.
What does this exchange point to? Was it a case of pilot action—inadvertent or deliberate? Or does it show confusion in the cockpit over how and why the fuel supply to engines was cut off? The selective use of this brief exchange has kept experts, industry watchers, and the public at large guessing, with many drawing whatever conclusion they deem fit; whatever they might want to believe.
The CVR is extremely sound-sensitive and generally picks up even the slightest amount of noise, like the drop of a pilot's pen to the cabin floor, even in the high-ambient-noise environment in the cockpit during take-off. So, it is highly probable that any manual fuel switch operation would have been recorded by the CVR, given that it's a spring-loaded switch that makes a distinct metallic click sound when it is pulled up and moved between its two modes—RUN and CUTOFF, multiple people aware of these operations have said.
Then, of course, there is use of the term 'transitioned' to describe the RUN to CUT OFF, which further adds to the ambiguity. The report nowhere states that the switches were physically moved. Yet, just the way it is written and structured, and the use of selective, cherry-picked information has many believing that it implicitly points a finger at the pilots, who are not here to defend themselves. There is also no time stamp mentioned on the brief exchange between the pilots quoted in the report. So, it is not clear at what stage of the 30-odd-second flight did that exchange actually take place, which is critical information required to piece together the chronology of events leading up to the worst aviation disaster involving an Indian airline in four decades.
The question then is: why not just release the full or more detailed parts of the CVR transcript? That could give a clear insight into the cockpit environment and the correspondence between the pilots before and after that brief, paraphrased exchange that has been left hanging in the preliminary report. In the initial report on the Ethiopian Airlines Boeing 737 MAX crash of 2019, Ethiopian authorities had released significant portions of the CVR information. This was the crash that triggered the global grounding of the Boeing 737 MAX jets at the time. If there is indeed any plausible reason for withholding a substantial part of the CVR transcript, then why just release a couple of paraphrased lines that add to the speculation?
The time difference of one second between the two fuel control switches changing modes—from RUN to CUTOFF—has also raised the question whether it could be done manually in such rapid succession by a pilot. This has led some pilots to believe that this is more indicative of a deeper issue with the electrical signals or the software that the Boeing 787 is heavily reliant on operationally. But the initial report is completely silent on the status of the investigation when it comes to the electrical and other systems of the aircraft.
Backend electronics and signals
With this silence and in the absence of more information from the CVR, there is now considerable speculation in certain quarters on whether the switches were indeed flicked by one of the pilots—inadvertently or otherwise—or whether the switch transition signal to the system was due to any technical, mechanical, or software issue. The report did not issue any recommendation to other operators of the Boeing 787-8 aircraft and its GE engines, suggesting that at this stage, the investigators do not have a reason to believe that there was any issue with the plane or its engines. Some experts have opined that the Enhanced Airborne Flight Recorder (EAFR)—the black box—would most likely record the signal that the switches have transitioned, not the actual physical movement of the switches.
When the fuel control switch is moved, there are multiple micro switches that are triggered, which send signals to different aircraft systems by way of electrical signals. One of these would be the FADEC, or the Full Authority Digital Engine Control. Modern day aero-engines are invariably configured with a FADEC system that takes the input in terms of the thrust demand based on the current state of the engine and the flight conditions, controls the engine so as not to exceed any of the limiting parameters of the engine while at the same time providing the best response. Theoretically, an issue with the FADEC could lead to issues with engine performance. Given that the FADEC is a safety critical system, adequate redundancy is configured into the system to provide the necessary reliability and availability.
Some experts have also opined that the Thrust Control Malfunction Accommodation (TCMA) system, designed to detect and prevent risks associated with engine thrust malfunctions, should also be looked into. A glitch related to the TCMA, which works with the FADEC, could possibly lead to misreading of the aircraft's position and speed, and initiate thrust reduction without pilot intervention, they said.
Then there is the electrical wiring interconnect system (EWIS), which encompasses all the wires, cables, connectors and related parts that carry electrical power and signals throughout an aircraft. Modern planes like the Boeing 787 rely heavily on electrical systems for functions like avionics, lighting and flight controls. EWIS could potentially face various environmental factors like temperature changes and moisture, which can cause wear and tear over time, especially in older aircraft. Faulty wiring or electrical malfunctions can pose serious safety hazards. Boeing has a somewhat patchy record on this, given that there have been whistleblower allegations about wiring not being properly routed over sharp edges, which could potentially cause some sort of electrical arcing or short circuiting.
Then there are different spar valves, different fuel control valves, all of which make contact once a switch has moved into that RUN position. The final report is likely to look at all this. But the way the information has been documented throughout the preliminary report, there is no real discussion of any potential system faults, other than a vague reference to a 2018 non-mandatory Special Airworthiness Information Bulletin (SAIB) by the US Federal Aviation Administration (FAA) about potential disengagement of the locking mechanism on the fuel control switches on certain Boeing aircraft models. But then the report itself goes on to suggest that the issue SAIB might not have a bearing as the ill-fated aircraft's thrust control module—which houses the fuel control switches among other instruments—were replaced in 2019 and 2023.
Aviation experts and commentators, in India as well as overseas, have been critical of the way India has handled information flow so far in the investigation, including the preliminary probe report. It is high time that the AAIB and the country's civil aviation establishment clarify what must be clarified, debunk misinformation, and open channels of regular flow of official information.
Sukalp Sharma is a Senior Assistant Editor with The Indian Express and writes on a host of subjects and sectors, notably energy and aviation. He has over 13 years of experience in journalism with a body of work spanning areas like politics, development, equity markets, corporates, trade, and economic policy. He considers himself an above-average photographer, which goes well with his love for travel. ... Read More
Anil Sasi is National Business Editor with the Indian Express and writes on business and finance issues. He has worked with The Hindu Business Line and Business Standard and is an alumnus of Delhi University. ... Read More