> On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure. Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 Attachment 2 relating to loss of control issue (also see above) were NOT implemented by Air India. The stated MN4 computer with faulty soldering, that might weaken and lose contact due to the thermal stress after a number of cycles, interprets data and commands fuel metering valves - with the lost contact attaching the MN4 processor to the EEC intermittent electrical contact, loss of signal processing and engine control faults can occur. The SB writes under conditions for the SB: "An LOTC (Loss Of Thrust Control) event has occurred due to an EEC MN4 microprocessor solder ball failure." According to discussions in the industry it may be possible with the number of cycles VT-ANB had already completed, the solder balls were weakened sufficiently to detach the MN4 from the EEC momentarily due to loads during the takeoff rotation leading to the loss of control of thrust and shut down of the engines.
Still quite early in the investigation, and so many things to consider. I don't know why online communities have been so quick to gravitate towards the murder/suicide theory. I thought aviation enthusiasts of all people would want to keep an open mind until every other possibility is ruled out, however minuscule it might seem.
> I don't know why online communities have been so quick to gravitate towards the murder/suicide theory.
Because the hardware failure theories seem preposterously far-fetched and require an unnecessary multiplication of deities.
Your ghost in the machine needs to be “just so” so that it can cause both switches to be read in “cutoff” nearly simultaneously. Then, 10 seconds later one of the switches needs to be read in “run”, then 4 seconds after that the second one needs to read “run”. You also need to explain why there have been zero single engine failures of this type before this double failure.
The ghost also needs to explain why one pilot asked the other “why did you cutoff?” instead of something like “what happened to the engines?” (which is the more natural response, unless you already know the switches are in cutoff).
There's also maintenance lapses, faulty repairs, defective parts, and as far as software goes I can think of n number reasons how a ghost can manifest itself inside program logic. This is a new gen plane that relies more on software than any other before, and has in fact seen a couple of incidents with loss of thrust, both related to software. I think it's more prudent to be asking hard questions around these than to outright dismiss it as an open and shut case. Besides, the murder/suicide angle is the least interesting outcome. Because there's nothing you can do after that, other than to just move on.
There's also the timing. Maybe there's something specific about takeoff that makes it more likely for the failure to occur. However, assuming there's not, then the odds of this occuring at takeoff (the worst possible time) instead of any other time are extremely low. Takeoff accounts for a tiny percent of the plane's operation.
My concern would be that the investigation in this case is more likely to be biased towards a system failure. Disgracing a major flag carrier is something very few regulars have the independence and courage to get away with.
The way i read what avherald highlighted is that a part that the manufacturer said should be replaced wasn't and failed as the manufacturer said it will. So it would point to the airline maintenance right now.
What the bbc says is truncated and omits the info about the failing part, so people can point towards murder suicide because they don't have all the info.
Which is why you should always read avherald first...
10 years ago the dynamics could perhaps be as you sketched between regulators and the carrier but today it is more complex.
Air India was government owned company till 2020s when it was sold back to the TATA group from whom it was originally nationalized from in the 1960s.
Stakeholders like regulators, employees individually could have different PoV or interests in the change .
Regulatory leadership could just as easily want to prove why this de nationalization was bad if so inclined as they could be for not wanting embarrass the flag carrier.
So it would be hard to categorically say that regulator has vested interest in protecting the flag carrier
The one thing automatic system failure theory can't explain is whether there is a reverse connect from the machine back to the switches where if the machine decides to cut off fuel, would the physical switches toggle to cut-off or stay in run position while the fuel is actually cut off, this would require an actuator setup to flip the switches from inside the system which there is no documentation of if that is even support let alone reported?
Respectfully, media reports on what the investigation is focusing on should be taken with a grain of salt unless said media is known to be reputable and have credible sources.
If they had a credible indication of a technical failure that causes engines to randomly shut down, they would have already grounded 787 fleets, which hasn't happened.
> On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure. Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 Attachment 2 relating to loss of control issue (also see above) were NOT implemented by Air India. The stated MN4 computer with faulty soldering, that might weaken and lose contact due to the thermal stress after a number of cycles, interprets data and commands fuel metering valves - with the lost contact attaching the MN4 processor to the EEC intermittent electrical contact, loss of signal processing and engine control faults can occur. The SB writes under conditions for the SB: "An LOTC (Loss Of Thrust Control) event has occurred due to an EEC MN4 microprocessor solder ball failure." According to discussions in the industry it may be possible with the number of cycles VT-ANB had already completed, the solder balls were weakened sufficiently to detach the MN4 from the EEC momentarily due to loads during the takeoff rotation leading to the loss of control of thrust and shut down of the engines.
Still quite early in the investigation, and so many things to consider. I don't know why online communities have been so quick to gravitate towards the murder/suicide theory. I thought aviation enthusiasts of all people would want to keep an open mind until every other possibility is ruled out, however minuscule it might seem.
> I don't know why online communities have been so quick to gravitate towards the murder/suicide theory.
Because the hardware failure theories seem preposterously far-fetched and require an unnecessary multiplication of deities.
Your ghost in the machine needs to be “just so” so that it can cause both switches to be read in “cutoff” nearly simultaneously. Then, 10 seconds later one of the switches needs to be read in “run”, then 4 seconds after that the second one needs to read “run”. You also need to explain why there have been zero single engine failures of this type before this double failure.
The ghost also needs to explain why one pilot asked the other “why did you cutoff?” instead of something like “what happened to the engines?” (which is the more natural response, unless you already know the switches are in cutoff).
There's also maintenance lapses, faulty repairs, defective parts, and as far as software goes I can think of n number reasons how a ghost can manifest itself inside program logic. This is a new gen plane that relies more on software than any other before, and has in fact seen a couple of incidents with loss of thrust, both related to software. I think it's more prudent to be asking hard questions around these than to outright dismiss it as an open and shut case. Besides, the murder/suicide angle is the least interesting outcome. Because there's nothing you can do after that, other than to just move on.
There's also the timing. Maybe there's something specific about takeoff that makes it more likely for the failure to occur. However, assuming there's not, then the odds of this occuring at takeoff (the worst possible time) instead of any other time are extremely low. Takeoff accounts for a tiny percent of the plane's operation.
1 reply →
My concern would be that the investigation in this case is more likely to be biased towards a system failure. Disgracing a major flag carrier is something very few regulars have the independence and courage to get away with.
The way i read what avherald highlighted is that a part that the manufacturer said should be replaced wasn't and failed as the manufacturer said it will. So it would point to the airline maintenance right now.
What the bbc says is truncated and omits the info about the failing part, so people can point towards murder suicide because they don't have all the info.
Which is why you should always read avherald first...
1 reply →
10 years ago the dynamics could perhaps be as you sketched between regulators and the carrier but today it is more complex.
Air India was government owned company till 2020s when it was sold back to the TATA group from whom it was originally nationalized from in the 1960s.
Stakeholders like regulators, employees individually could have different PoV or interests in the change .
Regulatory leadership could just as easily want to prove why this de nationalization was bad if so inclined as they could be for not wanting embarrass the flag carrier.
So it would be hard to categorically say that regulator has vested interest in protecting the flag carrier
The one thing automatic system failure theory can't explain is whether there is a reverse connect from the machine back to the switches where if the machine decides to cut off fuel, would the physical switches toggle to cut-off or stay in run position while the fuel is actually cut off, this would require an actuator setup to flip the switches from inside the system which there is no documentation of if that is even support let alone reported?
They are simple toggle switches without actuators. The switches are Honeywell P/N 4TL837-3D. Source[1]. Data sheet[2].
[1] https://ad.easa.europa.eu/blob/NM-18-33.pdf
[2] https://www.mouser.com/datasheet/2/187/honeywell_hwscs06627_...
Do your lights control your switches?
Respectfully, media reports on what the investigation is focusing on should be taken with a grain of salt unless said media is known to be reputable and have credible sources.
If they had a credible indication of a technical failure that causes engines to randomly shut down, they would have already grounded 787 fleets, which hasn't happened.
Kneejerk patriotic reaction ?