Update 13 July 2025:
The report can be read via this link.
https://aaib.gov.in/Reports/2025/Accident/Preliminary%20Report%20VT-ANB.pdf
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The report released on Friday was a preliminary one, as required by ICAO standards; the final report will be released 12 months from the crash date. The short, purely factual report, inevitably leaves many questions unanswered. It mentions a notice issued by the US FAA recommending that the locking mechanism for the cut off switches be checked to ensure that it is not disabled, as some have been found to be. It is a recommendation, not a mandatory notice and so Air India say they did not follow it up.
However, the aircraft in question had the console around the Thrust Levers and the switches replaced twice, latterly in 2022 and there is no defect shown in the technical log. If we assume that the switches were functioning as designed, which seems likely, then it takes a conscious decision to move them from RUN to CUT OFF, as they must be lifted first and then moved. The CUTT OFF selection on this flight occurred sequentially, first engine 1 then number 2, which suggests deliberate actio
A Boeing training captain who flies a 777, which has similar switches, tells me that it is common to find pilots resting their hands on this part of the centre console, thus placing them near the switches. So here we are back where we started. However, would the non-handling pilot (in this case the captain) be doing that at this stage of the take off?
Once the call to “rotate” has been made the handling pilot will have both hands on the control column, the other pilot should be monitoring everything and awaiting the call to raise the undercarriage; they never got that far.
During an appearance on Indian YV channel NDTV yesterday, one Indian pilot asserted that he was convinced that the captain shut off fuel deliberately in order to crash the aircraft. This is the unsayable fear in other discussions that have taken place since the report was released. It is an awful thing to contemplate but all options should be considered and it is likely that the investigators have a lot more information than is in the short report. That they do not say which pilots asked why CUT OFF was selected and which one denied doing it, indicates a degree of circumspection on the investigator’s part. No doubt they need to look further into this action before publishing any more.
What the report does do, is to tell us why the engines lost thrust and that the aeroplane did exactly what it was designed to do. One of the pilots swiftly reset the switches to RUN, which initiated a restart sequence automatically, which was successful but too late to deliver enough thrust. The Auxiliary Power Unit (APU) began its automated start sequence and the Ram Air Turbine (RAT) deployed, as designed in the event of total power loss.
For those close to the deceased this may do little to ease the anguish and of course the pilots reputations are now in question as well; a harrowing situation for all involved and it may be some time before full answers are available.
UPDATE added 16/6/25 see foot of page:
Air India AI171 crashed on take-off from Ahmedabad for reasons that are as yet unexplained. The Boeing 787 Dreamliner, destined for London Gatwick and with 242 people on board, crashed within 30 seconds of take-off, landing in a built up area and hitting a medical school. The resultant fireball and impact killing all on board, save for one passenger, seated in Row 11a, who walked free of the wreckage. Several on the ground also perished in the crash.
The two things that are required for successful flight at the take-off stage are lift and thrust in combination. In this case it seems that one or both of those things were missing or were lost.
There are some poor quality videos that have now been verified, that show the aircraft getting airborne, only to start sinking and failing to climb. There has been speculation on possible reasons and two are as follows. Where the wing flaps set for take-off correctly? Were the engines delivering correct take-off thrust?
The videos are not clear enough to provide concrete evidence of either issue but initially it was thought that flaps were not in the correct position or that they had somehow retracted early, dumping lift. In one video that has sound, sparked speculation that the engines were not sounding as if they were at full thrust. For one engine to fail is always considered possible, for two to fail simultaneously is extremely rare and would need and exceptional explanation.
What might such an explanation be? Fuel contamination – unlikely. Foreign object ingestion, such as birds. Possible, as a recent crash in South Korea demonstrated but in that case these were medium sized birds (Teal) and in huge quantities and so a truly exceptional event. So far, no evidence of such an issue had emerged in the Air India case.
Each take-off is calculated by the crew, using the appropriate calculation method for the aircraft concerned and once the data for the airfield is established (Runway length, altitude above sea level, temperature, wind etc) then the aircraft weight can determine the amount of thrust required for that particular take-off.
If incorrect data slips into the calculations it will affect the thrust setting arrived at. Engines perform best at low temperatures and so if an outside air temperature of, say 25C is used instead of the real OAT of 35C, then the calculations will say you need less thrust than you really do. This is a hypothetical example of how the wrong thrust setting can be used and it has happened before. I am not suggesting that this is the cause of this crash, it may be something entirely different but we are seeking explanations for the aircraft not climbing away as planned and it is just one possibility out of several.
Modern jets have computerised systems that control the engines. A software or maintenance issue is always possible but again, extremely unlikely, although nothing can be ruled out at this stage.
It is important to say that all public transport aircraft must meet or exceed the performance standards set out in Performance A, the schedule that manufacturers and operators have to meet for certification of each aircraft design.
In simple terms, this means that the aircraft must be capable of experiencing the failure of an engine, at the most critical point of take-off (IE stopping is no longer an option within the runway) and continue the planned take-off, climb away safely, clearing all obstacles and, if need be, continue to destination or divert to a suitable airfield.
Crews also train for such an event, as well as others, in the simulator and this is one of the many reasons why flying has become so safe. Obviously the standard of training is important and it cannot be said that all operators meet the same standards. That is the subject of my book, as it is the vital element that joins aircraft design in keeping us all safe. That is NOT to say that I am implying any criticism of this crew in this instance, merely setting out the principles ; we cannot know if there was a crew element in this crash or if the reason was outwith their control.
Large twin engine aircraft, such as the B787, have the largest margin of performance over the regulations of any aircraft in the history of aviation. They deliver more thrust on one engine than older designs produced on two; why is this so? The regulatory requirement to experience an engine failure, and continue safely, was created when most heavy aircraft had four engines and so the failure of one, left them with three more. The big twins have to meet the same rules and so that remaining engine is very powerful indeed and hence, very safe.
Finally, there is the mystery of the Ram Air Turbine (RAT) which it seems may have deployed automatically, which it is designed to do when a major electrical failure occurs. Did the aircraft suffer a total electrical failure and if so, would it have stopped or reduced performance of the engines? A RAT is a device that falls into the airstream in flight and is driven by the airflow, to generate electricity and/or hydraulic power; many aircraft types have them.
In principle the engines should keep running but often a catastrophe occurs when factors combine and as yet we can’t tell what other issues may have been involved, such as software on a highly computerised aircraft. A total electrical failure is a very rare event and why it should happen suddenly and at this stage of flight is unclear. We do know that when the B787 was first introduced, it had a couple of battery fires whilst on the ground. This was dealt with long ago but we must ask if it would still be possible on this particular aircraft.
As theories and information continue to trickle out, yet more ideas may emerge but the ultimate result will be at least the preliminary report from investigators.
One of the flight recorders has been recovered and so some answers should be possible within a few weeks all being well; assuming that the data is recoverable. If any more information emerges I will update the page.
UPDATE:
Increasingly, the feeling of a dual engine issue seems the most likely explanation for the sudden change of fortune with this take-off. Modern aircraft systems need to know if the aircraft is on the ground or airborne and so as soon as the weight comes off the wheels and the undercarriage extends, the systems, “know,” that the aircraft is flying. Modern jets have fully digital engine controls and if there were some kind of fault in the airborne mode that did not exist in the ground mode, then that could explain why a successful take-off, changed to the inability to fly.
An electrical fault could cause a series of failures if it were serious enough. At altitude, this may be dealt with by the crew but at such a low heith above the ground, the crew would have no time to analyse and deal with a sudden catastrophic event. Whilst it is hard to envisage a situation such as this, something major must have occurred to cause such a major problem.