London bound Air India 787 Dreamliner crashes at Ahmedabad

What we know for certain from a few accounts are:
1. a loud bang
2. pilots saying "Mayday"

Without going into really off the wall stuff..

Is it possible that one engine failed after V1 (the loud bang), but the other engine didn't spool up to full (max thrust) so there wasn't enough power creating lift to keep the plane airborne beyond a few sec?

No, we don’t know any of those things for certain, they’ve just been posted on the internet with no confirmation by anyone official. If both engines weren’t at full thrust by 80kts then a 787 should consider an RTO. A loud bang could be anything and eyewitnesses are notoriously unreliable as their recollections are usually all over the place.
 
Would you not get the backfiring if it was a birdstrike?
Not always, if the engines are seriously damaged and the whole thing seizes then no thrust is produced anymore to backfire (surge). ATC would see it happen though and there would be bird debris on the runway so it would be obvious. Engines and their casings are designed to cope with this but a birdstrike resulting in a blade failure is a very violent event. I've not heard of anything or seen any evidence of this in the videos though.

Fuel contamination is a possibility and that would prove that the decision to open the airport just 3hrs later was absolutely crazy. There is also the possibility of some form of sabotage but who knows.

There was an instance of something like this with BA38 which crashed short of the runway when landing at Heathrow due to loss of thrust. This was caused by iced fuel clogging a heat exchanger (fuel is used to cool oil) and then fuel couldn't get to the engines.

This won't be the case here as there's no way the fuel could freeze in 40°c but if a major mechanical engine failure isn't the problem then my money would be on some fuel problem barring a crazy mishap from the pilots.

Heathrow777_runway.jpg
 
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Not always, if the engines are seriously damaged and the whole thing seizes then no thrust is produced anymore to backfire (surge). ATC would also see it happen and there would be bird debris on the runway so it would be obvious. Engines and their casings are designed to cope with this but a blade failure is a very violent event. I've not read of anything like this or seen any damage or impact in the videos though.

Fuel contamination is a possibility and that would prove that the decision to open the airport just 3hrs later was absolutely crazy. There is also the possibility of some form of sabotage but who knows.

There was an instance of something like this with BA38 which crashed short of the runway when landing at Heathrow due to loss of thrust. This was caused by iced fuel clogging a heat exchanger (fuel is used to cool oil) and then fuel couldn't get to the engines. This won't be the case here but if a major mechanical failure isn't the problem then my money would be on some fuel problem barring a crazy mishap from the pilots.

Heathrow777_runway.jpg

Yeah I remembered the Sully landing and this BA38. Both were miracles in their own right.. no power.. managed to crash land with no deaths..

Really really lucky on both counts with good skilled crews.
 
Yeah I remembered the Sully landing and this BA38. Both were miracles in their own right.. no power.. managed to crash land with no deaths..

Really really lucky on both counts with good skilled crews.
The timing of the BA38 crash was a miracle in itself.

Had that happened just 4-5 minutes earlier then that plane would have potentially dropped into central London, or more likely the Thames with a repeat of the Sully landing in a 777!
 
No idea here but the video of the electrical systems inside the plane failing on a previous flight (on the same plane, I think?), the report from the survivor that the lights flickered just after departure, the pilot mayday call indicating a loss of thrust, and the possibility of RAT deployment — all sketchy and I am not sure confirmed in any cases — is there some catastrophic electrical failure that could disable the airplane including the thrust right at rotation?
 
No idea here but the video of the electrical systems inside the plane failing on a previous flight (on the same plane, I think?), the report from the survivor that the lights flickered just after departure, the pilot mayday call indicating a loss of thrust, and the possibility of RAT deployment — all sketchy and I am not sure confirmed in any cases — is there some catastrophic electrical failure that could disable the airplane including the thrust right at rotation?

I think it's conjecture even if it's not confirmed yet that lack of maintenance over time would cripple any airplane!
 
No idea here but the video of the electrical systems inside the plane failing on a previous flight (on the same plane, I think?), the report from the survivor that the lights flickered just after departure, the pilot mayday call indicating a loss of thrust, and the possibility of RAT deployment — all sketchy and I am not sure confirmed in any cases — is there some catastrophic electrical failure that could disable the airplane including the thrust right at rotation?
The flight recorders will tell all, so no point speculating.
 
Every accident has a unique set of circumstances occurring that results in a tragedy.

Speculation at the moment is pointless and probably wrong.

The flight and cockpit voice recorders will give the investigators a huge insight of what happened, but the deeper question will be why?

It could be anything.
 
No idea here but the video of the electrical systems inside the plane failing on a previous flight (on the same plane, I think?), the report from the survivor that the lights flickered just after departure, the pilot mayday call indicating a loss of thrust, and the possibility of RAT deployment — all sketchy and I am not sure confirmed in any cases — is there some catastrophic electrical failure that could disable the airplane including the thrust right at rotation?
The 787 has two batteries to support critical systems such as the flight computers and engine digital controls if power is lost. They are charged automatically whenever power is available on the ground or inflight so they can always provide emergency power if needed.

With any total power loss the aircraft will switch to be powered by the batteries but they don't last forever so the RAT is also deployed automatically to provide power. This is needed on long haul aircraft because they fly over the ocean for long periods where the batteries would discharge before reaching a diversion.

Without the RAT the batteries would discharge over time and once discharged all power is lost and then it would be impossible to control the aircraft as the flight computers would stop working. There are no mechanical linkages between the controls in the cockpit and the control surfaces on modern aircraft nowadays, it's all done by computer and computers need power. I doubt this happened as the aircraft did look controllable, they just had no thrust.

Total power loss would require multiple component failures to happen at the same time, it's unheard of. You'd need the power loss problem, then RAT failure and then battery failure. It's the equivalent odds of three simultaneous but separate random events where your car engine fails, then your brakes stop working and then you blow a tyre.
 
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Would the RAT system ever be deployed so early in a flight? And would the pilots even consider it if they were trying to deal with a sudden loss of thrust?
 
The 787 has two batteries to support critical systems such as the flight computers and engine digital controls if power is lost. They are charged automatically whenever power is available on the ground or inflight so they can always provide emergency power if needed.

With any total power loss the aircraft will switch to be powered by the batteries but they don't last forever so the RAT is also deployed automatically to provide power. This is needed on long haul aircraft because they fly over the ocean for long periods where the batteries would discharge before reaching a diversion.

Without the RAT the batteries would discharge over time and once discharged all power is lost and then it would be impossible to control the aircraft as the flight computers would stop working. There are no mechanical linkages between the controls in the cockpit and the control surfaces on modern aircraft nowadays, it's all done by computer and computers need power. I doubt this happened as the aircraft did look controllable, they just had no thrust.

Total power loss would require multiple component failures to happen at the same time, it's unheard of. You'd need the power loss problem, then RAT failure and then battery failure. It's the equivalent odds of three simultaneous but separate random events where your car engine fails, then your brakes stop working and then you blow a tyre.
Not sure exactly what emergency systems are powered from the DC bus on the 787. Likely an auxiliary hyd pump and/or electric actuators for some or all of the control surfaces. There will also be a reversionary mode for the flying controls which cuts away some of the more complex systems and provides limited instruments and flying controls. There would have been more than enough in the batteries for the length of the flight.

Also, I would suspect that a total loss of power wouldn't result in a instantaneous loss of hydraulic pressure in the main system given that it's a pressurised system and there should be enough to at least provide some limited control assistance for a short period of time.

As you said, the flight looked stable. Pitch, roll and yaw seemed to be under control, but if there isn't enough forward thrust to provide dynamic lift then it's going to quickly result in an uncontrolled decent into the ground.
 
Tragic . Those poor people . Carn`t imagine the terror they went through . Mercifully it was only seconds for them unlike the 31/2 minutes the Air france crew and passengers went through over the Atlantic a few years back . I can only imagine the terror they went through . Unable to do anything to save themselves knowing death was seconds / minutes away . One of my worse nightmares and the reason that i`ve never flown in my 62 years . That and the fact i`ve watched way to many series of Aircraft Investigation over the years . . .
 
Tragic . Those poor people . Carn`t imagine the terror they went through . Mercifully it was only seconds for them unlike the 31/2 minutes the Air france crew and passengers went through over the Atlantic a few years back . I can only imagine the terror they went through . Unable to do anything to save themselves knowing death was seconds / minutes away . One of my worse nightmares and the reason that i`ve never flown in my 62 years . That and the fact i`ve watched way to many series of Aircraft Investigation over the years . . .
Same here. Wont fly, or try not to. I have watched too many of those documentaries to bring me to the conclusion that there are people who dont know what they are doing in all walks of life including Airline pilots, engineers, manufacturers, etc.

That Air France one, over the atlantic? I think that was the one where the co pilot was basically flying the plane into the sea because he was disorientated? I think that was the one.
 
Same here. Wont fly, or try not to. I have watched too many of those documentaries to bring me to the conclusion that there are people who dont know what they are doing in all walks of life including Airline pilots, engineers, manufacturers, etc.

That Air France one, over the atlantic? I think that was the one where the co pilot was basically flying the plane into the sea because he was disorientated? I think that was the one.
I watch many of these Air Crash Investigation programmes and YouTube Pilots views on them. It gives me more confidence to fly due to the forensic investigations and sbsequent adoptions of improvements both to equipment, procedures and training. Thus it is by far the safest form of transport.

If you hold that view then I'd be far more worried about being in a car as there are far more drivers with FA knowledge of what they are doing, drunk or driving unworthy vehicles.

As for the Air France flight. The passengers did not know a thing as even the pilots were unaware they were gradually descending.
 

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