Pilots: Deliberate ambiguity in report timeline to shift blame

Time of India

17-07-2025

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Kolkata: Serving and retired pilots have expressed concern over what they term "deliberate" ambiguity in the timeline mentioned in the preliminary probe report by Aircraft Accident Investigation Bureau (AAIB) on the AI 171 crash.
They allege this has been done to absolve the aircraft manufacturer of responsibility and pin the blame on the pilots.
They also point out that the word "transition" of fuel switches used in the report attempts to insinuate that they were manually moved. "This is an American expression. In India, it would normally have been written: The switches were moved. It is the fuel valves that transition while the switches can move from RUN to CUT OFF or vice versa," a veteran pilot said.
While several timelines are mentioned in the report, it is unclear at the crucial phase immediately after takeoff, when the two engines momentarily shut down after fuel flow stopped. AAIB provides the timestamp to the exact second for a number of actions. The aircraft started rolling at 8:07:37 UTC (13:37:37 IST, ie, 37 seconds past 1.37pm). The aircraft and ground sensors recorded the lift-off at 08:08:39 UTC (13:38:39 IST).
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It then states the aircraft achieved the maximum recorded airspeed of 180 knots (333 kmph) at 08:08:42 UTC (13:38:42 IST).
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Thereafter, the timelines become unclear. It says immediately after, engine 1 and engine 2 fuel cutoff switches transitioned from RUN to CUT OFF position one after another with a time gap of 01 second. It then states: "In the cockpit voice recording, one of the pilots is heard asking the other why he cut off.
The other pilot responded that he did not do so."
"When did all of this happen and in which sequence? That is a crucial segment of the flight when something catastrophic happened that took down the plane. It is not possible to move both switches from RUN to CUT OFF in a second. The SOP as laid down in the manual for reviving engines during a dual engine failure is to move the switches from RUN to CUT OFF and back to RUN. The pilots in the ill-fated aircraft did so and we know the engines were revived, but the plane crashed because it did not gain enough altitude to clear the buildings," another captain explained.
The report goes on to state that CCTV footage obtained from the airport showed the Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off, but the time is not mentioned. The next timestamp is when the RAT hydraulic pump began supplying hydraulic power, 08:08:47 UTC (13:38:47 IST). A pilot pointed out that since the RAT takes around 7-8 seconds from auto deployment to begin functioning, the plane should have lost the engines around 08:08:40 UTC (13:38:40 IST).
"If that is so, then how did the plane achieve the maximum airspeed 2 seconds later at 08:08:42 UTC (13:38:42 IST)?" he said.
Another pilot said it was critical to know the exact conversation that took place in the cockpit from the start of the takeoff run to the Mayday call, adding: "This is not just for the sake of learning why flight AI 171 crashed but to ensure that another flight does not meet the same fate in future."
Another captain also pointed out that both pilots were wearing headsets and spoke on different channels, as is mandatory procedure during takeoff. "Then why is there no clarity on who said what, it's available in the cockpit voice recorder?" he said.