Air India Crash Flight 171 – TWIN Engine Failure?!?
There is a lot of speculation about the causes of the Air India crash, flight 171 from India to England. In this article I’ll cover the main theories so far, see if they add up and identify which one makes the most sense. Disclaimer: I am not an aviation expert
Pilot Error
This one came from a big aviation YouTube channel. The YouTube channel proposed that the pilot reduced flaps instead of lifting the landing gear.
It turns out these levers are in different places in the cockpit. Not likely to have happened, and even if it did, I think I’m right in saying the plane should have had more than enough power to overcome this issue.
At the time of writing, I don’t think there are any other theories out there that suggest pilot error was the cause and pilot error for the Air India crash is not on the agenda any more.
Flaps
Another big theory. This one has also been quashed if I am reading the situation correctly. The theory said flaps were not in the correct position and this is what caused the plane to lose altitude.
From what I have read on this, a number of things have pushed this theory off the table.
First is that the plane should have had enough power to overcome and issue like this.
Second, if the flaps were in the wrong position, the plane’s computers would have told the pilots about it (flashing lights/buzzers) in a way they could not ignore.
Third, there have been photos of the wreckage that appear to show the flaps in the correct position.
Fuel Contamination
I think I’m correct in saying that at the time of writing this theory is still on the table. However I am skeptical for a couple reasons.
The biggest reason I’m not convinced is that the thrust from both engines was equal for the entire flight which suggests each engine had exactly the same contamination at the same time. I guess it’s possible but probably unlikely.
Secondly there is no smoke whatsoever from the engines which suggests to me all the fuel entering the engines was burned completely and properly. I would expect, as a non-expert, to expect some puffs of smoke from at least one of the engines.
Thirdly, there are sensors in the fuel tanks of 787 to detect contaminated fuel eg fuel which contains water.
Yes, fuel contamination could be the cause but I personally think it is unlikely with the information that I have at the moment.
Twin Engine Failure
Related to the fuel contamination issue I guess. The theory is both engines failed in some way at the same time. I’m assuming when people say twin engine failure they are talking about something going wrong inside the engines themselves.
I think the chances of this happening, at exactly the same time is extremely remote. And again, we don’t see any signs the engines are malfunctioning in the videos (apart from the lack of power), no smoke at all, no unevenness in power between engines.
Personally, I’m ruling this one out.
Bird Strike
From what I’ve seen of bird strikes they cause a bit of fire and smoke. There is nothing like that in the footage I’ve seen of the crash. I’m ruling this out also.
Landing Gear Not Retracted
Another theory that was pounced on by some Aviation experts on YouTube as an obvious error by the pilots. If you have a power problem, you should retract the gear to reduce drag to help keep the plane flying and they jumped to the conclusion that the Air India pilots failed to do this.
However, someone has released a video showing how the landing gear on the 787 works.
When the plane is coming the land, the front of the gear would be tilted upwards.
In the videos of the Air India crash I have seen, the landing gears at the centre of the plane appear to be level, or perhaps tilted slightly forward (lower at the front).
In other words, the videos suggest the pilots did instruct the landing gear to retract but the gear only made it part way through the sequence. This would make sense if the plane had hydraulic pressure failure. What suggests a failure of the hydraulic system? The deployment of the RAT.
Having said all that, someone has commented the following.
That the doors for the landing gear compartments were not down and this suggests that the gear was not instructed to retract. Apparently the doors drop by gravity and therefore would still work with hydraulic failure. And additionally the landing gear tilts forward as the plane takes off.
This last sentence makes me doubt the entire comment. How would the landing gear know if the plane is going to remain airborne or touch down again? Surely the gear would always be in the landing position, ie front wheels tilted up until instructed to retract. I do not see any logical reason why the wheels would tilt forward if the gear had not been instructed to retract.
Another theory I’m dismissing for now at least.
Sabotage
Did the pilots deliberately fly the plane into the ground? It wouldn’t be the first time.
But again, the fact that the RAT appears to be deployed suggests that the plane was experiencing a major mechanical/electrical issue.
Unless more evidence comes forward, I think we can put this theory firmly on the back burner.
Incorrect Flight Data
Did the pilots input incorrect flight data into the flight plan and did this lead to the flight computer giving inaccurate take off settings.
Very interesting theory this and I think by my use of the terminology it’s obvious I don’t know anything about this computer or the effect it has on the plane.
What I would say is, if the pilots did make a mistake and enter the wrong weight, for example they said the plane was 180 tonnes while it was actually 227 tonnes. I would like to think that during takeoff they would have the ability to add more thrust than the flight computer suggested in order to take off. I mean, I would hope that just because a pilot entered the wrong weight, the plane wouldn’t then limit the amount of maximum thrust available to the pilots.
I’m assuming the plane would not limit power capability and with that assumption, I am putting this theory right down at the bottom in order likeliness, next to twin engine failure.
ECU Safe Mode
So far, I think this is the most likely theory. A complete shut down of the electrical system due to a failure of the generator control units (ECUs). I’m presuming when the Generator Control Units (GCUs) shut down, all electrical power is lost, except for power provided by the RAT and potentially, this could lead to the fuel pumps shutting down, leading to fuel starvation in the engines. This would explain the apparent complete loss of power and the deployment of the RAT. It would also explain the apparent simultaneous shut down of both engines at the same time.
The GCU ECU problem has been covered here and here. However, I think it should be noted that it is apparently unlikely for the ECUs to be powered for over 248 days continuously. Nevertheless, as a layman, this issue would fit with what I have seen.
In Summary – Air India Crash
What makes the Air India crash bizarre is that there isn’t anything obviously wrong with the flight. If the crash site was actually a runway, to all intents and purposes it would have looked like a normal landing. No smoke, no flames, no unusual movements, nothing.
Any single system failure is unlikely to bring a plane down. And I think I’m safe in saying, even with one engine inoperative, the plane to could still take off, one engine has enough power.
For me, for two absolutely key systems (the engines) with backup and redundancies to fail, and at exactly the same time with no outward indication that they have failed suggest something major has gone wrong and that something major has to link both of the engines.
And at the moment, the GCU fail safe mode ticks all of the boxes. To quote the Guardian
“a software bug that causes a complete electric shutdown of Boeing’s 787 and potentially “loss of control” of the aircraft.”
https://www.theguardian.com/business/2015/may/01/us-aviation-authority-boeing-787-dreamliner-bug-could-cause-loss-of-control
The fuel system on the 787 is almost entirely electrical, no electrical power equals almost no fuel to the engine. Almost because engines can suction feed but the power needed for takeoff I think can not be sustained by suction alone. Cruise maybe, not takeoff.
At the moment, with the information I have and as a layman, GCU failure seems most likely, these are my thoughts on the Air India crash of flight 171. At the time of writing.
