FPJ Exclusive: Simulator Data Sheds New Light On AI Flight 171 crash

Chennai: When Air India flight 171 crashed on June 12, 2025, killing 260 people, the report put out by India’s Aircraft Accident Investigation Bureau (AAIB) said both engines lost power shortly after takeoff when fuel was cut and then a relight occurred. Even though the AAIB report does not blame the pilots -- a fact that Solicitor General Tushar Mehta highlighted in Supreme Court on Nov 13, 2025 -- still Western media ran with a story of Capt Sumeet Sabharwal cutting off the fuel.

Now new evidence shows when the fuel cutoff and relight AAIB talks about could have happened; and by which component and why. Fresh tests on a Boeing 787 Level D full‑flight simulator in Europe, by the Federation of Indian Pilots (FIP), which represents roughly 6,000 pilots, seem to indicate that the fuel switches were in RUN for the first 11 seconds of the flight -- for the relight behaviour AAIB report talks about.

If fuel switches were in RUN for first 11 seconds -- it would then point to crew innocence; and that neither Capt Sumeet nor First Officer Clive Kunder's hands were anywhere near the fuel switches till the engines flamed out, said Air India 171 engineers. "As per new data, the likely sequence is engine failure. Attempt to restart engine by the crew and only then fuel switches were touched," they add.

So in the commissioned 10 simulator runs, done by the FIP, replicating the official AAIB timeline -- the goal was simple. Whether the timeline implied in the AAIB report stood up against reality.

The AAIB report says, "As per the EAFR data both engines N2 values passed below minimum idle speed ...at about 08:08:47 UTC." N2 is the engines' core speed and once this passes below minimum idle then the plane would need massive amounts of energy to start it again. Usually this is supplied by an emergency unit called the auxillary power unit (APU). But AI 171's APU did not come online.

On AI 171, the APU's inlet door was opening at 08:08:54 UTC, as per AAIB report. And it would need another 50-60 seconds to get started -- which means its role is zero; zilch -- in a flight that was only 32 seconds in duration, said engineers. The other emergency power called the Ram Air Turbine (RAT) is a smalle generator that cannot spin the engine core; but can help by providing sparks to a relight effort if the plane was already travelling at a speed of 250-300 knots, where the engine fan blades are spinning fast enough. AI 171 was at 180 knots and fast decelerating, so RAT didn't help, said engineers.

So then if there was no electrical power left on the plane, then how does AAIB report talk of a reight where "Engine 1’s core deceleration stopped, reversed and started to progress to recovery” and that Engine 2 “was able to relight”?

Engineers and the simulator data now show that this engine behaviour likely happened immediately after fuel cutoff; between 08:08:45-50 UTC; when the engine's core was still spinning fast enough for a relight commanded by engine computer FADEC.

The simulator runs bear that out in numbers. Across nine documented tests, the N2 values at the moments labelled “1 Eng Start” and “2 Eng Start” – which the software tags at around 08:08:52 and 08:08:56 in the scenario – sit between roughly 32- 59%. Fuel flow, which is controlled by engine computer FADEC, at those points is 0.0 to 0.6, effectively zero.

In other words, when the simulator reaches the state AAIB describes – N2 of both engines below minimum idle – there is no genuine restart. The cores are too slow, the fuel is essentially off, and the engines never actually come back to a self‐sustaining idle.

That gap between what the report claims and what the engines can physically do matters far beyond the decimal points.

If the AAIB’s implied relight story (for which it does not give timestamps) cannot be reconciled with either GE’s manuals or real‐world simulator behaviour, then its central causal chain – “pilot switches to cutoff → engines go below minimum idle → pilot switches back to RUN → engines relight” – collapses. "You are left with a different casual chain; which is likely engine computer FADEC cuts off fuel during power disruption → FADEC attempts relight → engines go below minimum idle → pilots attempt recycle," said Air India 787 engineers.

If the engines could not have relit at 08:08:52 and 08:08:56, when commanded by the crew -- then GE documents and simulator data point to a much smaller window in which a relight could possibly occur: the first few seconds after fuel cutoff at 08:08:44, while the cores are still spinning fast and the engine‐driven generator – the permanent magnet alternator, or PMA – is delivering full voltage.

But FADEC can only do that if the cockpit fuel switches remain in RUN. That, in turn, would mean that for the first 11 seconds of the 32‐second take‐off, nobody in the cockpit touched the fuel switches. And the only time they were touched was when First Officer Clive likely attempted a fuel switch recyle for restarting engine, after Captain Sumeet took over controls, as reported by Free Press Journal.

Capt Randhawa, president of FIP, says another break in AAIB report's causal link is the deployment of emergency power or Ram Air Turbine (RAT). "AAIB report does not tell us when the RAT deployed. Now it implied RAT was deployed as a result of engine cutoff. Nowe we have simulator data which shows RAT needs 10-14 seconds to start supplying hydraulic power after a cutoff."

On AI 171, RAT started generating hydraulic power at 08:08:47 UTC after plane liftoff at 08:08:39 UTC, as per AAIB report. "So this show, RAT was deployed due to a prior electrical disturbance on the plane. And not because main engines failed. This shows that the evidence points more towards systems failure, than pilot error, said Capt Randhawa.