BA 777 crash at heathrow

An airport worker told the BBC the pilot on the Boeing 777 had said he had lost all power, and had been forced to glide the plane into land.

The worker also said the pilot had told him all the electronics had also failed.

BBC

I supose a bird strike could explain the loss of power from the engines? but what would explain both the loss of power and the electronics failure both at the same time?

Well the only other accidents like that where it would land short (or potentially land short) would be from an exhaustion of the fuel, which would explain the loss of engine power as well as electrical power. Such a sudden lack with no warning seems strange to me though, as there should be plenty of warning before something like that happens.

That said, I would wonder if there is anything that could cause a failure of both engines, such as a technical fault shutting them off. A bird strike would only damage one engine at a time, and besides engines are tested to withstand that.

reply to post by apex


www.youtube.com...

thats what happens with an engine bird strike

I was thinking more like this, but even so, it shouldn't cause total loss of power, and the chances of simultaneous bird strikes on two engines must be pretty low.

reply to post by apex


Even if birds hit both engines simultaneously, that shouldn't result in loss of electrical power to the aircraft as described by the pilot.

The pilot said he had a "total loss of power", which is lucky he was in a Boeing seeing as they don't use fly by wire for their avionics (I am led to believe), whereas an Airbus would have been almost impossible to control without power given it's avionics are FBW.

Originally posted by apex
I was thinking more like this, but even so, it shouldn't cause total loss of power, and the chances of simultaneous bird strikes on two engines must be pretty low.

The chances are higher to have both engines fail then to have dual birdstrikes.

Also the comments on control of flight systems etc. I'm lead to believe that Airbus and possibly Boeing planes have a small wind turbine that will deploy if power is loss and the turbine runs the basic flight systems.

yeah they do use FBW with no back up (aside from 3 or 4 redundant fbw systems - one fails the next takes over etc) - haven`t had manual reversal for years , so when the power failed , it crashed. there was a crash a few years ago when all the redundant systems failed at once and the plane came in very badly - but they got it down with mimimal loss of life.

uk.news.yahoo.com...

One eyewitness, Steve Bell, said the wheels were not down on landing, and he heard a grating noise.

systems failure on lowering undercarraige?

Originally posted by Canada_EH
The chances are higher to have both engines fail then to have dual birdstrikes.

Is that simultaneous or sequential though?

Also the comments on control of flight systems etc. I'm lead to believe that Airbus and possibly Boeing planes have a small wind turbine that will deploy if power is loss and the turbine runs the basic flight systems.

You mean the Ram air turbine? It works fine in principle but its small and doesn't apparently generate all that much at landing speeds. The so called "Gimli Glider" (an Air Canada flight that ran out of fuel) had difficulty on landing apparently:

The engines also supply power for the hydraulic systems, without which an aircraft the size of the 767 cannot be controlled. However, aircraft designs are required to accommodate such a failure, and a ram air turbine automatically deployed on the underbelly of the aircraft. In theory, the forward velocity of the aircraft would spin the ram air turbine, a propeller-driven generator, providing enough power for the hydraulics to make the aircraft controllable, although this proved problematic during landing.

But, if it's already at landing speed, the deployment of a ram air turbine probably can't do all that much.

www.flightglobal.com...

The crew managed to control the descent to a touchdown with wings level, on grass just over the perimeter fence at Heathrow, on the 27L extended centreline. The gear was down, flaps were set at about 20°, and the indications are that the crew had started the auxiliary power unit.

cartridge start of the apu so they knew what had happened and had got the very last ditch back up running to bring the falling brick back down


kudos to the captain when the board is all red and the busses have been dumped

My hats off to an aircrew that can keep a glider that big and heavy in the air to make a landing everyone walks away from.

reply to post by TheAvenger


Indeed!! An Indian work colleague of mine said had this been an airline such as India Air or Pakistan Airways, it would have plowed into the tarmac nose first. Apparently of all the airlines he's flown, with BA you hardly notice your landing.

even the passengers didn't even think they had crashed until the evacuation began, must have been that smooth a crash! I was once on a KLM flight from Heathrow to Schippol and it felt like the pilot really hated the tarmac when we got to Holland!

Here is flight globals head flight safety guys talking about the crash. He mentions that he can't think of a accident like this with both engines out etc and I was thinking that the Kegworth air disaster of 1989 with the Britich midlands 737-400 is quite similar to this and hopefully the reason for this crash isn't similar to the 737-4 pilot mistakes and unfamiliarity with the plane and systems.
en.wikipedia.org...



[edit on 18-1-2008 by Canada_EH]

Here is a very short video showing the aircraft on final approach just clearing the airport boundary, it does not show the touchdown. The AoA looks a little higher than normal.

One of the reports I saw said that rather than loose all power in both engines the actual problem was that the engines did not respond to the input from the pilot for more power - ie he had throttled back on the approach, as he required more power he pushed the levers forward and got no response. - I'm not all that sure on the precise procedure for landing a large twin engine such as a 777, but it does make sense that power is applied at the last minute for control (not for acceleration - just to balance forces and tip a hat to sir Newton)

I only heard this on one of the many reports I've seen ~ think it was Sky news... all the rest say total loss of power in both engines. But to my mind loss of response in both engines is far more likely than loss of both engine function (they are separate systems ~ only connected by fuel and control systems).

It also fits with one of the eye witness accounts that said that they herd the engines 'shut down, and then wind down' - that witness said that it was on reverse thrust, but that could be hard to tell.

Originally posted by stumason

The pilot said he had a "total loss of power", which is lucky he was in a Boeing seeing as they don't use fly by wire for their avionics (I am led to believe), whereas an Airbus would have been almost impossible to control without power given it's avionics are FBW.

The Boeing 777 has a fly by wire control system, as will the Boeing 787. Aircraft have alternative power sources (as someone has noted, the RAT is one of them), and also the engines will still provide some power through windmilling.

As to Airbuses becoming 'almost impossible to control' in the event of a power loss, please look up Air Transat Flight 236, which suffered a complete fuel exhaustion over the North Atlantic, resulting in total loss of engines more than 100 miles from a runway. The pilots managed to successfully divert to the Azores and glide her to a wheels down landing, resulting in minor damage to the aircraft and only minor injuries to passengers.

Aircraft have redundant systems.

reply to post by RichardPrice


That flight you mentioned would of had considerably more airspeed and a lot more height - a lot more options!! Still very skilled to put down safely.

Originally posted by Now_Then
One of the reports I saw said that rather than loose all power in both engines the actual problem was that the engines did not respond to the input from the pilot for more power - ie he had throttled back on the approach, as he required more power he pushed the levers forward and got no response. - I'm not all that sure on the precise procedure for landing a large twin engine such as a 777, but it does make sense that power is applied at the last minute for control (not for acceleration - just to balance forces and tip a hat to sir Newton)

He should have been at around 50% power during the final approach (yes, there is an awful lot more power involved in landing than you think, flaps and other landing aids add a hell of a lot more drag to the aircraft and thus require extra thrust to counter that drag) so he should not have been 'throttled back'.

The engine power loss comments are only coming through to us as third and fourth hand accounts from untrusted sources - pay no heed to them until the AAIB initial report is out, which will be some time this weekend.

Originally posted by Now_Then

That flight you mentioned would of had considerably more airspeed and a lot more height - a lot more options!! Still very skilled to put down safely.

I mentioned that flight purely as a rebuttal to the insinuation that Airbus aircraft would be nearly uncontrollable in a power loss situation.

reply to post by RichardPrice


Agreed as I had mentioned early with the RAT post and the mention the the azors landing as well.