Air India Flight AI171 (Boeing 787-8) Crash

[RDY4WAR]

I read this on Facebook. I'm not sure of the accuracy.

A preliminary investigation into the fatal crash of an Air India Boeing 787, which claimed the lives of 270 people, has identified a malfunction in the captain’s seat locking mechanism as the primary cause of the accident. The report indicates that during takeoff, the captain’s seat unexpectedly slid backward, inadvertently causing the pilot to pull the throttle levers into the idle position.

This sudden reduction in engine thrust occurred just seconds after liftoff, resulting in an immediate loss of power and a stall at low altitude. The aircraft subsequently crashed into a nearby building that housed medical staff.

“The co-pilot’s efforts to recover control were obstructed by the captain’s reclined position,” the report stated.
Cockpit data outlined a critical 14-second window:
+12 seconds: Captain’s seat slides back
+15 seconds: Co-pilot exclaims, “We’re losing thrust!”
+26 seconds: Aircraft stalls at an altitude of 214 feet
Investigators also noted that the Boeing 787’s throttle system lacked key safety features, such as reverse-motion protection and weight-based throttle lockouts, design flaws that may have prevented the incident.

 

[Dave Hess]

^^^
I just saw a video talking about the seat shifting rearward.

 

[john_pifer]

^^^
I just saw a video talking about the seat shifting rearward.

I read this on Facebook. I'm not sure of the accuracy.

Hard to believe.

Not about the seat mechanism malfunctioning. That’s believable.

But not being able to regain control?

All he’d have to do is push it back up. I mean, in a situation that’s life or death, you’re telling me a professional pilot doesn’t have the presence of mind to realize he’s just accidentally pulled the throttles back as his seat slid back, and needs to get them pushed back up?

Or, at worst, the FO should be easily able to take control (“my airplane, I’ve got it”), and re-apply power.

I’m not buying it.

 

[fdcg27]

I think this theory has already been debunked.
First, the PF would not have had his hands on the thrust levers at that stage.
Second, even if he had the PM would have immediately shoved them forward.
Oh, and the aircraft was flown brilliantly during its unplanned descent. It was not stalled.

 

[Just a civilian pilot]

Totally ridiculous.

Some flight attendants told me about that one last week.

 

[RDY4WAR]

I feel validated in my skepticism.

 

[Astro14]

I think this theory has already been debunked.
First, the PF would not have had his hands on the thrust levers at that stage.
Second, even if he had the PM would have immediately shoved them forward.
Oh, and the aircraft was flown brilliantly during its unplanned descent. It was not stalled.

Well, we already had an upset in flight due to seat movement on this type of airplane, so it’s not that crazy of a theory.

PF should have his hands on the thrust levers at that point.

Captain removes their hand at V1 - PF puts their hand back on at rotation.

But if the seat moved back - could the PM have reached the yoke to keep flying?

The 787 has flight envelope protections built in - you have to work to stall it - it would have stayed at the same pitch if someone let go of the yoke.

 

[Just a civilian pilot]

Curious what their sops say because I have never flown for an airline where the PF puts their hands back on the thrust levers after rotation for safety reasons ( in case your seat slides back or incapacitation ). It’s not allowed at my airline until it’s time to select climb thrust.

That said, I have seen a few pilots try to put their hands on the thrust levers just after rotation ( new hires that used to do it at their previous company according to them when asked why they do it ) but I tell them to take their hands off them until climb thrust as soon as soon as I see their hands move towards them. Makes me very uncomfortable seeing a pilot do that.

Sorry folks, I have a very hard time believing this one and any airline that allows that shouldn’t allow it until thrust reduction altitude.

There is no advantage to keeping you hand on the thrust levers right after rotation and even if you need TOGA for safety reasons ( wind shear ) , it will be be a 1 second delay pushing the thrust levers full forward which is safer in the long run in case the PF , for whatever reason, pulls the thrust levers back.

If the crash was caused by this, which I highly doubt ( accidentally retarded ), it will prove how dangerous it can be.

Seat sliding back/pilot incapacitation is why we don’t allow it.

I can’t see any scenario where a pilots seat sliding back causing the PF to retard both thrust levers to idle causing a plane to crash ( 600 feet is more than high enough for the other pilot to salvage the situation , especially when self preservation kicks in ) could happen with another pilot sitting beside them.

If this did happen, we would have seen a dramatic increase in pitch in those videos but we never saw it.

It’s unsafe to allow pilots to do it ( put hands on TL right after rotation ).

Hopefully any airline that allows it runs a sim scenario where the PF becomes incapacitated right after take off ( with their hands on the TL ) and retards both to idle to see how the other pilot reacts.

 

[y_p_w]

Just a thought, but given the technology is out there, is it time for cockpit video recording? And yeah I get that many pilot organizations have said they don’t want them.

 

[Just a civilian pilot]

Just a thought, but given the technology is out there, is it time for cockpit video recording? And yeah I get that many pilot organizations have said they don’t want them.

Why would you need to “film” what pilots are doing when CVR and FDR ( plus airlines flight data analysis ) already tell investigators what’s going on in the cockpit?

If the dual power loss was because the PF had his hands in the TL and his seat slid back ( notice there was no pitch change in the video ) , they already have enough information to know as I am sure it will also show up on the CVR.

How about this before they start filming us……don’t allow pilots to keep their hands on the TL below thrust reduction altitude given at least another airline had an upset caused by a pilots seat sliding backwards.

 

[Just a civilian pilot]

Not sure about the B787 but if the PF seat slid full back ( and hand on TL ) , and the pilot pulled full back on the control stick on the Airbus ( and pulled both engines into idle ) , the pitch would increase momentarily until the low speed protections kicked in.

I can’t see how any other aircraft would not , initially, react the same way ( if it has a low speed protection envelope ) if a pilot pulls full back even as they retard both TL to idle because the aircraft still has some speed and energy above the low speed protections envelope. The speed has to get very low before it kicks in ( lots of elevator authority until it kicks in ).

That’s assuming the other protection device ( PM ) let it happen.

I have sim in August and I will ask the check pilot if we can try it on take off and I will report back.

V1, rotate, hand on the TL ( contrary to SOP for safety reasons ) and simulate my seat sliding back and both TL going to idle and the stick yanked full back.

I know what’s going to happen ( assuming the PM doesn’t take over ).

Edit: also, Airbus low speed protections ( in addition to limiting pitch to avoid stalling ) will also select TOGA even if both TL are at idle position ( and engine haven’t quit , obviously ).

That scenario couldn’t happen in the Airbus and I am curious if Boeing has a similar low speed protection regarding automatically applying full TOGA if a pilot pulls full back ( and engines at idle ).

Sorry folks, I don’t fly the Boeing and compare these situations to how the Airbus would deal with them.

 

[Just a civilian pilot]

Since we have been talking about AI , here’s what AI says about low speed protection on the B787.

So, if this is true, why would that B787 crash because one pilots seat slides back ( while the other pilot doesn’t respond ) and they pull back on the control column and both thrust levers to idle if part of the B787 low speed protections involves the aircraft automatically applying power?

Overview


The Boeing 787 Dreamliner features low-speed protection as part of its flight control system, particularly in Normal Law. This protection, which includes features like LE autoslat extension, helps prevent stalls by enhancing lift and stability at slower airspeeds. Additionally, the autothrottle system can automatically engage to prevent a stall by increasing thrust if the aircraft approaches a low-speed or stall condition.

 

[2.7ecoboostFordBronco]

The PF where I work puts their hands on the thrust levers after the “gear up” call is made. We’ve had MD-11 autothrottles initiate uncommanded thrust reductions (to idle) at low altitude. After those incidents putting a hand on the thrust after gear up is called was mandated airline wide even on types other than the MD. We are required to to keep a hand there until flaps are retracted, and on descent when flaps are extended the PF must put a hand on the thrust levers again.

 

[Just a civilian pilot]

The PF where I work puts their hands on the thrust levers after the “gear up” call is made. We’ve had MD-11 autothrottles initiate uncommanded thrust reductions (to idle) at low altitude. After those incidents putting a hand on the thrust after gear up is called was mandated airline wide even on types other than the MD. We are required to to keep a hand there until flaps are retracted, and on descent when flaps are extended the PF must put a hand on the thrust levers again.

If that’s the case with the MD11, then that’s the safer thing to do.

We don’t have that problem on any aircraft at my airline so it’s hands off.

The PF puts their hand on the TL no later than the FAF on final ( final approach fix….1500 feet ) with our airline.

I have read about too many ( even though very very rare ) incidents involving sudden pilot incapacitation to convince me it’s not a safe practice unless proven otherwise ( bad auto throttle design ).

 

[Dave Hess]

Who is analyzing the CVR data ?

 

[Astro14]

Not sure about the B787 but if the PF seat slid full back ( and hand on TL ) , and the pilot pulled full back on the control stick on the Airbus ( and pulled both engines into idle ) , the pitch would increase momentarily until the low speed protections kicked in.

I can’t see how any other aircraft would not , initially, react the same way ( if it has a low speed protection envelope ) if a pilot pulls full back even as they retard both TL to idle because the aircraft still has some speed and energy above the low speed protections envelope. The speed has to get very low before it kicks in ( lots of elevator authority until it kicks in ).

That’s assuming the other protection device ( PM ) let it happen.

I have sim in August and I will ask the check pilot if we can try it on take off and I will report back.

V1, rotate, hand on the TL ( contrary to SOP for safety reasons ) and simulate my seat sliding back and both TL going to idle and the stick yanked full back.

I know what’s going to happen ( assuming the PM doesn’t take over ).

Edit: also, Airbus low speed protections ( in addition to limiting pitch to avoid stalling ) will also select TOGA even if both TL are at idle position ( and engine haven’t quit , obviously ).

That scenario couldn’t happen in the Airbus and I am curious if Boeing has a similar low speed protection regarding automatically applying full TOGA if a pilot pulls full back ( and engines at idle ).

Sorry folks, I don’t fly the Boeing and compare these situations to how the Airbus would deal with them.

It has exactly that feature in the auto throttles.

Even the 757 has that.

 

[Just a civilian pilot]

It has exactly that feature in the auto throttles.

Even the 757 has that.

So, if someone pulls the thrust levers back to idle after take off, what would happen like with the seat sliding back theory with the pilot yanking back on the control column and thrust levers ?

If the answer is the thrust will automatically increase even with the TL at idle by accident , doesn’t that make the seat sliding back theory impossible ( aside from the PNF unlikely to let things go that far )?

I am o.k with crash theories as long as they make sense.

 

[2.7ecoboostFordBronco]

So, if someone pulls the thrust levers back to idle after take off, what would happen like with the seat sliding back theory with the pilot yanking back on the control column and thrust levers ?

If the answer is the thrust will automatically increase even with the TL at idle by accident , doesn’t that make the seat sliding back theory impossible ( aside from the PNF unlikely to let things go that far )?

I am o.k with crash theories as long as they make sense.

You can pull the thrust levers to idle by hand in most Boeings even with the autothrottle on. The autothrottle will fight you in certain modes, and try to advance, but it’s much weaker than a human arm and can easily be overridden even if you don’t turn it off. It doesn’t matter how slow or fast you get there is nothing the autothrottle can do if you’re physically holding the thrust levers at idle or max or any point in between. You will just hear the servo whirring but it only takes about as much arm strength as overriding a toaster spring to defeat it. I don’t know about the 787 specifically but I’d be surprised if it was too much different.

 

[Dave Hess]

You can pull the thrust levers to idle by hand in most Boeings even with the autothrottle on. The autothrottle will fight you in certain modes, and try to advance, but it’s much weaker than a human arm and can easily be overridden even if you don’t turn it off. It doesn’t matter how slow or fast you get there is nothing the autothrottle can do if you’re physically holding the thrust levers at idle or max or any point in between. You will just hear the servo whirring but it only takes about as much arm strength as overriding a toaster spring to defeat it. I don’t know about the 787 specifically but I’d be surprised if it was too much different.

Great info.

Which Boeing aircraft are you currently flying ?

 

[Just a civilian pilot]

You can pull the thrust levers to idle by hand in most Boeings even with the autothrottle on. The autothrottle will fight you in certain modes, and try to advance, but it’s much weaker than a human arm and can easily be overridden even if you don’t turn it off. It doesn’t matter how slow or fast you get there is nothing the autothrottle can do if you’re physically holding the thrust levers at idle or max or any point in between. You will just hear the servo whirring but it only takes about as much arm strength as overriding a toaster spring to defeat it. I don’t know about the 787 specifically but I’d be surprised if it was too much different.

Thanks.

What I meant was, if the B787 has the same same low speed protected flight envelope, how is it possible for it to crash because a pilots seat slides back and they pull back on the control column, and thrust levers?

Any aircraft with a protected low speed flight envelope won’t let you stall because it will decrease elevator authority ( AoA ) to prevent a stall plus will go to TOGA even if the TL were at idle.