The preliminary report is due out tomorrow. 

 

FWIW, Here's what The Air Current has to say:

 

 

 

 

Air India crash investigation focuses on movement of engine fuel control switches - The Air Current

 

https://theaircurrent.com/

 

They're (TAC) being widely quoted, but that may just be out of a lack of other theories floating around.  There are other venues speculating that it was likely a software glitch.  I'm not expecting much from the preliminary report because they've still got months and months of work to do.

2 hours ago, stevenl said:

I think it may be interesting because the Indians will try to put the blame on Boeing. 

 

It will be interesting whatever but the Indians may have no choice about any blaming.

5 hours ago, nauseus said:

 

It will be interesting whatever but the Indians may have no choice about any blaming.

They do. They took the lead in the investigation and have from the start tried to shift blame set public opinion away from an Indian fault.

In the end it may be Boeing is to blame, but personally i very much doubt that. 

8 minutes ago, stevenl said:

They do. They took the lead in the investigation and have from the start tried to shift blame set public opinion away from an Indian fault.

In the end it may be Boeing is to blame, but personally i very much doubt that. 

 

So do I, and the evidence might show that. That's why I said Indians may have no choice about any blaming.

'Why did you cut off?' pilot heard to say in cockpit voice recording re fuel cut-off switches.
The other pilot responded that he did not do so.

https://www.bbc.co.uk/news/live/cx20p2x9093t?post=asset%3A3337a2c5-fe15-469c-bbe6-6ca359352c49#post

 

10 minutes ago, merck said:

'Why did you cut off?' pilot heard to say in cockpit voice recording re fuel cut-off switches.
The other pilot responded that he did not do so.

https://www.bbc.co.uk/news/live/cx20p2x9093t?post=asset%3A3337a2c5-fe15-469c-bbe6-6ca359352c49#post

 

 

Thanks. Just saw that. It just gets more strange and sad.

 

 

India's AAIB has released its Preliminary Report into the crash of AI flight 171:

The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42  UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned  from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1  and N2 began to decrease from their take-off values as the fuel supply to the engines was cut  off. In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.  The other pilot responded that he did not do so.

As per the EAFR data both engines N2 values passed below minimum idle speed, and the  RAT hydraulic pump began supplying hydraulic power at about 08:08:47 UTC.

As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about  08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with  the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also  transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to  RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC)  automatically manages a relight and thrust recovery sequence of ignition and fuel introduction.  The EGT was observed to be rising for both engines indicating relight. Engine 1’s core  deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to  relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to  increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11  UTC At about 08:09:05 UTC, one of the pilots transmitted “MAYDAY MAYDAY MAYDAY”. The  ATCO enquired about the call sign. ATCO did not get any response but observed the aircraft  crashing outside the airport boundary and activated the emergency response. At 08:14:44 UTC, Crash Fire Tender left the airport premises for Rescue and firefighting. They  were joined by Fire and Rescue services of Local Administration.

The flap handle assembly sustained significant thermal damage. The handle was  found to be firmly seated in the 5-degree flap position, consistent with a normal takeoff flap  setting. The position was also confirmed from the EAFR data. The landing gear lever was in  “DOWN” position.

The thrust lever quadrant sustained significant thermal damage. Both thrust levers were found  near the aft (idle) position. However, the EAFR data revealed that the thrust levers remained  forward (takeoff thrust) until the impact. Both fuel control switch were found in the “RUN”  position. (fig.13) The reverser levers were bent but were in the “stowed” position. The wiring  from the TO/GA switches and autothrottle disconnect switches were visible, but heavily  damaged.

The aircraft is equipped with two Enhanced Airborne Flight Recorders (EAFR) part number  866-0084-102. The EAFR are fitted at two locations, one in the tail section at STA 1847 and  other in the forward section at STA 335. The two EAFRs are similar in construction and record  a combined data stream of digital flight data and cockpit voice information, with both stored  on the same device.

The downloaded flight data contained approximately 49 hours of flight data and 6 flights,  including the event flight. The recovered audio was two hours in length and captured the  event. Initial Analysis of the recorded audio and flight data has been done.

UPDATE
The AAIB (Air Accident Investigation Bureau) preliminary report can be found here:

 

https://aaib.gov.in/What's New Assets/Preliminary Report VT-ANB.pdf

 

Better to watch Captain Steeeve

 

https://youtu.be/MD64uYK926o?si=ZwURwIxzySmmqYDp

On 7/10/2025 at 11:39 AM, stevenl said:

I think it may be interesting because the Indians will try to put the blame on Boeing. 

I hope you and others who said "the Indians" would try to blame Boeing are ashamed of themselves. And I would love to know what you based that assumption on? 

https://www.bbc.co.uk/news/live/cx20p2x9093t

 

Peter Goelz, a former managing director of the US's National Transportation Safety Board (NTSB), says he’s impressed by the preliminary report.

 

Goelz, who has led several accident investigations, says India's Aircraft Accident Investigation Bureau, responsible for the report, "needs to be praised for preparing such a detailed preliminary report.”

 

“Oftentimes when dealing with such a high-profile former flag carrier of a nation, the reports are far less detailed and candid.”

“This was a very detailed report. For that the AAIB should be praised.”

 

 

 

Preliminary Report published.

1 hour ago, josephbloggs said:

I hope you and others who said "the Indians" would try to blame Boeing are ashamed of themselves. And I would love to know what you based that assumption on? 

 

It's still early in the process.

 

I think it may be interesting because the Indians will try to put the blame on Boeing. 

 

According to your "pattern of thought", what other nationalities would do the same as the Indians (as you say) and what nationalities would do the opposite?

 

We learn every day...

 

 

49 minutes ago, impulse said:

 

It's still early in the process.

 

This is interesting. Can't post a PDF here but here's the link. From 2018. 

https://ad.easa.europa.eu/blob/NM-18-33.pdf/SIB_NM-18-33_1

 

This Special Airworthiness Information Bulletin (SAIB) is to advise registered owners and operators

of The Boeing Company Model 717-200 airplanes; Model 737-700, -700C, -800, and -900ER

series airplanes; Model 737-8 and -9 airplanes; Model 747-400, -400D, -400F, -8, and -8F series

airplanes; Model 757-200, -200CB, -200PF, and -300 series airplanes; Model 767-200, -300, -

300F, -400ER, and -2C series airplanes; Model 787-8, -9, and -10 airplanes; Model MD-11 and

MD-11F airplanes; and Model MD-90-30 airplanes of the potential for disengagement of the fuel

control switch locking feature.

 

The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel

control switches were installed with the locking feature disengaged. The fuel control switches (or

engine start switches) are installed on the control stand in the flight deck and used by the pilot to

supply or cutoff fuel to the engines. The fuel control switch has a locking feature to prevent

inadvertent operation that could result in unintended switch movement between the fuel supply and

fuel cutoff positions. In order to move the switch from one position to the other under the condition

where the locking feature is engaged, it is necessary for the pilot to lift the switch up while

transitioning the switch position. If the locking feature is disengaged, the switch can be moved

between the two positions without lifting the switch during transition, and the switch would be

exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in

an unintended consequence, such as an in-flight engine shutdown.

 

 

5 hours ago, Georgealbert said:

UPDATE
The AAIB (Air Accident Investigation Bureau) preliminary report can be found here:

 

https://aaib.gov.in/What's New Assets/Preliminary Report VT-ANB.pdf

 

The report contains the section pictured below.

 

 

This section seems to highlights a relevant contextual factor, from the December 2018, U.S. Federal Aviation Administration (FAA) issued Special Airworthiness Information Bulletin (SAIB) NM-18-33.

 

The document warned of the "potential disengagement of the fuel control switch locking feature" on several Boeing models, including the 787. A disengaged locking feature could make the switches more susceptible to accidental movement.

 

NM-18-33 Can be found here;

 

https://ad.easa.europa.eu/ad/NM-18-33

 

 

 

 

Edit - sorry posted at the same time as @josephbloggs

 

 

 

5 minutes ago, josephbloggs said:

This is interesting. Can't post a PDF here but here's the link. From 2018. 

https://ad.easa.europa.eu/blob/NM-18-33.pdf/SIB_NM-18-33_1

 

This Special Airworthiness Information Bulletin (SAIB) is to advise registered owners and operators

of The Boeing Company Model 717-200 airplanes; Model 737-700, -700C, -800, and -900ER

series airplanes; Model 737-8 and -9 airplanes; Model 747-400, -400D, -400F, -8, and -8F series

airplanes; Model 757-200, -200CB, -200PF, and -300 series airplanes; Model 767-200, -300, -

300F, -400ER, and -2C series airplanes; Model 787-8, -9, and -10 airplanes; Model MD-11 and

MD-11F airplanes; and Model MD-90-30 airplanes of the potential for disengagement of the fuel

control switch locking feature.

 

The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel

control switches were installed with the locking feature disengaged. The fuel control switches (or

engine start switches) are installed on the control stand in the flight deck and used by the pilot to

supply or cutoff fuel to the engines. The fuel control switch has a locking feature to prevent

inadvertent operation that could result in unintended switch movement between the fuel supply and

fuel cutoff positions. In order to move the switch from one position to the other under the condition

where the locking feature is engaged, it is necessary for the pilot to lift the switch up while

transitioning the switch position. If the locking feature is disengaged, the switch can be moved

between the two positions without lifting the switch during transition, and the switch would be

exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in

an unintended consequence, such as an in-flight engine shutdown.

 

Like I said.  It's still early.  They have months of work to do.

Good info, BTW.

22 minutes ago, Georgealbert said:

The report contains the section pictured below.

 

 

This section seems to highlights a relevant contextual factor, from the December 2018, U.S. Federal Aviation Administration (FAA) issued Special Airworthiness Information Bulletin (SAIB) NM-18-33.

 

The document warned of the "potential disengagement of the fuel control switch locking feature" on several Boeing models, including the 787. A disengaged locking feature could make the switches more susceptible to accidental movement.

 

NM-18-33 Can be found here;

 

https://ad.easa.europa.eu/ad/NM-18-33

 

Edit - sorry posted at the same time as @josephbloggs

 

 

 

 

So, with the 'disengagement of the switch locking feature', the switches could, say, through strong vibrations, go from 'run to cut off' without either pilot having touched them?????? That is scary.

15 minutes ago, Will B Good said:

 

 

So, with the 'disengagement of the switch locking feature', the switches could, say, through strong vibrations, go from 'run to cut off' without either pilot having touched them?????? That is scary.

What is more scary is the fact that something that could cause both engines to shut down unintentionally - at any point in flight - was not deemed an "unsafe condition". From the same Special Airworthiness Information Bulletin (SAIB) NM-18-33 linked earlier:
 

Based on an assessment utilizing the limited data currently available at this time, the airworthiness

concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title

14 of the Code of Federal Regulations (14 CFR) part 39. The FAA will continue to monitor this

issue.

May be worth noting that back in 2018 Boeing still had massive influence over the FAA and was practically allowed to self certify their aircraft via the Organization Designation Authorization (ODA) program. That only changed in 2020. 

 

On 7/10/2025 at 12:04 PM, impulse said:

The preliminary report is due out tomorrow. 

 

FWIW, Here's what The Air Current has to say:

 

 

 

 

Air India crash investigation focuses on movement of engine fuel control switches - The Air Current

 

https://theaircurrent.com/

 

They're (TAC) being widely quoted, but that may just be out of a lack of other theories floating around.  There are other venues speculating that it was likely a software glitch.  I'm not expecting much from the preliminary report because they've still got months and months of work to do.

The flight and voice recorders seemed quite definitive but this is not something you can easily do by mistake. You'd need to put quite a bit of force to pull out the stick and move it to cut-of position. There are also metal brackets on the sides that prevent you from accidentally touching it - which was an issue on older planes where the stick could just be moved without pulling it out first and was a physical rather than electronic switch.

 

Pilot also said he didn't move it when asked. And there would be no reason for anyone to touch those switches in flight. They are to start/shut down engines, so generally only touched on the taxiway and at the gate, except in case of engine fire or detachment, etc.

 

Had this been older plane like 737-800, yes, it was possible to leave switches in position where vibration could accidentally move them to cut-off but not on 787.

 

Some serious questions. How could pilot switch (which is, if you have a manual car, equate to unknowingly pulling up the gear shift stick and moving it to reverse position) to cut-off without realising it, or, does the engine controller have the ability to physically move the switch on its own? If the latter, there would be a deadly flaw in Dreamliner engine fuel control system. If this was pilot error... I just can't see how this could be accidental. It borders on impossible.

8 minutes ago, tomazbodner said:

The flight and voice recorders seemed quite definitive but this is not something you can easily do by mistake. You'd need to put quite a bit of force to pull out the stick and move it to cut-of position. There are also metal brackets on the sides that prevent you from accidentally touching it - which was an issue on older planes where the stick could just be moved without pulling it out first and was a physical rather than electronic switch.

 

Pilot also said he didn't move it when asked. And there would be no reason for anyone to touch those switches in flight. They are to start/shut down engines, so generally only touched on the taxiway and at the gate, except in case of engine fire or detachment, etc.

 

Had this been older plane like 737-800, yes, it was possible to leave switches in position where vibration could accidentally move them to cut-off but not on 787.

 

Some serious questions. How could pilot switch (which is, if you have a manual car, equate to unknowingly pulling up the gear shift stick and moving it to reverse position) to cut-off without realising it, or, does the engine controller have the ability to physically move the switch on its own? If the latter, there would be a deadly flaw in Dreamliner engine fuel control system. If this was pilot error... I just can't see how this could be accidental. It borders on impossible.

 

A few posts above explain that there was an issue with defective (for lack of a more technical word) switches that were installed without the safety features.

 

I wonder if the inspection they (Air India) did on their other 787s immediately after the crash was to look for defective switches?   But that's just me wondering.  They cleared them to fly within a day so it couldn't have been a very deep dive inspection.

 

This wording from Boeing is odd......"if the switches were installed with the locking mechanism disengaged"......that reads to me like they installed switches without a locking mechanism.

As per the video below, the preliminary report also mentions that the module containing the fuel control switches on this particular plane had been replaced in both 2019 and 2023 (for unrelated reasons) and that no fuel control switch problems were noted. Nor had there been any reports from pilots on previous flights with this aircraft, of any problems with the switches. 

 

The former US Navy and commercial airline pilot in the video says the chances of one switch accidentally failing by itself would be a million to one. So the chances of both failing within one second (and at the time in the flight when it would be the most critical) would have to be astronomical. 

 

https://youtu.be/qrtRC6OkmiI?si=9hgT8f4n_h3upS3l

33 minutes ago, impulse said:

 

A few posts above explain that there was an issue with defective (for lack of a more technical word) switches that were installed without the safety features.

 

I wonder if the inspection they (Air India) did on their other 787s immediately after the crash was to look for defective switches?   But that's just me wondering.  They cleared them to fly within a day so it couldn't have been a very deep dive inspection.

I watched Petter's video (MentourNow) listed above - I watched his videos in the past... and partially agree with him and Ben who cohosted that session...

 

Locking mechanism is simply supposed to prevent moving the switches without pulling them out during the movement. Ben said that rules state that from rotation the hands are supposed to be on the yoke, nowhere near the thrust levers. But this is an assumption that both pilots actually followed the rules. It could be that hand was left on the levers longer and when moving the hand off them flipped the switches accidentally, and if both switches had locking mechanism broken (this plane was one of the first off the production line of 787) it would be potentially plausible.

 

But seems if that isn't the case, this looks deliberate. But why would you do something like that in the middle of the take-off? Surely if someone was going to crash the plane that would be done over the sea or in hard to reach mountainous area, with fuse for recorders pulled? Look at EgyptAir and Eurowings, SilkAir... it would just be a very strange stage of flight to do something like this deliberately...

21 minutes ago, GroveHillWanderer said:

As per the video below, the preliminary report also mentions that the module containing the fuel control switches on this particular plane had been replaced in both 2019 and 2023 (for unrelated reasons) and that no fuel control switch problems were noted. Nor had there been any reports from pilots on previous flights with this aircraft, of any problems with the switches. 

 

As I understand it, Air India didn't act on the 2018 safety bulletin because it was put out as discretionary.  An SAIB vs an AD.

 

On an aside, has anyone found another source for the Preliminary Report?  The Indian Gub'ment website is blocked here in China.  I can't tell on which side it's blocked.  I just can't access the report.

 

2 minutes ago, tomazbodner said:

I watched Petter's video (MentourNow) listed above - I watched his videos in the past... and partially agree with him and Ben who cohosted that session...

 

Locking mechanism is simply supposed to prevent moving the switches without pulling them out during the movement. Ben said that rules state that from rotation the hands are supposed to be on the yoke, nowhere near the thrust levers. But this is an assumption that both pilots actually followed the rules. It could be that hand was left on the levers longer and when moving the hand off them flipped the switches accidentally, and if both switches had locking mechanism broken (this plane was one of the first off the production line of 787) it would be potentially plausible.

 

But seems if that isn't the case, this looks deliberate. But why would you do something like that in the middle of the take-off? Surely if someone was going to crash the plane that would be done over the sea or in hard to reach mountainous area, with fuse for recorders pulled? Look at EgyptAir and Eurowings, SilkAir... it would just be a very strange stage of flight to do something like this deliberately...

 

I've contended for years (as if that matters to anyone) that they need to install cockpit video recorders now that the tech is so easily available.  That would put any mystery to bed, even if it did occasionally catch pilots picking their noses.

 

1 minute ago, tomazbodner said:

Surely if someone was going to crash the plane that would be done over the sea or in hard to reach mountainous area, with fuse for recorders pulled? Look at EgyptAir and Eurowings, SilkAir... it would just be a very strange stage of flight to do something like this deliberately...

I disagree - if you were to cut off fuel to the engines at a later stage, there would be a much better chance to restart them, as was attempted here (the switches were quickly put back to the "run" position, but there just wasn't enough time for them to regain thrust).

 

However by cutting off the fuel just after take off, you could pretty much guarantee that the plane was going to crash.

1 minute ago, impulse said:

 

I've contended for years (as if that matters to anyone) that they need to install cockpit video recorders now that the tech is so easily available.  That would put any mystery to bed, even if it did occasionally catch pilots picking their noses.

Was thinking of the same and remember some years ago when this topic came up and there was a serious discussion about mounting them on... Can't remember which crash that has followed but the CVRs weren't clear on who did what... then it was compared to Virgin Galactic where copilot accidentally moved something and the whole "plane" broke apart - captured on camera in cockpit.

 

Well, from MentourNow video linked above, this topic will be discussed in video that's getting released on Monday. Maybe that provides answers.

1 minute ago, tomazbodner said:

Was thinking of the same and remember some years ago when this topic came up and there was a serious discussion about mounting them on... Can't remember which crash that has followed but the CVRs weren't clear on who did what... then it was compared to Virgin Galactic where copilot accidentally moved something and the whole "plane" broke apart - captured on camera in cockpit.

 

Well, from MentourNow video linked above, this topic will be discussed in video that's getting released on Monday. Maybe that provides answers.

 

Sadly, YouTube is blocked here in China.  (And I've been warned by my ISP by phone against using a VPN).  I have to download Mentour Pilot on my monthly trips to Bangkok and watch them over the next 3 weeks.  I'll catch up next week when I fly back to BKK.