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Old 01-23-2008, 08:36 PM   #1  
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Default Computer failure most likely cause of 777 British Airways 38 accident

"Computer failure emerged yesterday as the most likely cause of flight BA038’s crash-landing, as its wreckage was removed from the southern runway at Heathrow Airport.

British Airways technical staff believe that the Boeing aircraft’s computerised control system caused both engines to fail during its final descent towards Heathrow on Thursday. All 136 passengers and 16 crew survived.

The aircraft was just two miles from touchdown and at a height of 600ft when it lost power suddenly. John Coward, the Senior First Officer, averted disaster by landing the craft just within Heathrow’s fence.

Experts said that a simultaneous mechanical failure of both engines was “unthinkable”. They suggested the fault must lie in the computer system that controlled the engines.

“There are separate autothrottles, a left computer and a right computer . . . everything is split,” a former 777 pilot said. “For both engines to fail at the same time it has got to have been commanded.” The Air Accidents Investigation Branch (AAIB) is examining all possibilities and has downloaded full data from the flight recorders. Its initial report made clear that it would focus on “the range of aircraft systems that could influence engine operation”.

Computer malfunction in 2005 almost caused a Malaysia Airlines 777 to stall, by slowing its airspeed from 270 knots to 158 knots and putting it into a 3,000ft climb. The pilot prevented disaster by disconnecting the autopilot and pushing the nose down. Another glitch last year caused a 777 to lurch to the right over the Atlantic. The captain had to quickly disengage the autopilot.

As BA’s stricken aircraft was moved to a hangar yesterday, other hypotheses were being aired. One was that a “bird strike” had shut down both engines. The impact of large birds hitting the fans inside the engine can cause damage, but no witnesses noted seeing flocks of birds near by. Another theory is that water got into the fuel.

The preliminary report from the AAIB into the incident is expected to be released in 30 days."

http://business.timesonline.co.uk/to...cle3221901.ece
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Old 01-24-2008, 05:18 AM   #2  
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Originally Posted by bgmann View Post
"Computer failure emerged yesterday as the most likely cause of flight BA038’s crash-landing, as its wreckage was removed from the southern runway at Heathrow Airport.

British Airways technical staff believe that the Boeing aircraft’s computerised control system caused both engines to fail during its final descent towards Heathrow on Thursday. All 136 passengers and 16 crew survived.

The aircraft was just two miles from touchdown and at a height of 600ft when it lost power suddenly. John Coward, the Senior First Officer, averted disaster by landing the craft just within Heathrow’s fence.

Experts said that a simultaneous mechanical failure of both engines was “unthinkable”. They suggested the fault must lie in the computer system that controlled the engines.

“There are separate autothrottles, a left computer and a right computer . . . everything is split,” a former 777 pilot said. “For both engines to fail at the same time it has got to have been commanded.” The Air Accidents Investigation Branch (AAIB) is examining all possibilities and has downloaded full data from the flight recorders. Its initial report made clear that it would focus on “the range of aircraft systems that could influence engine operation”.

Computer malfunction in 2005 almost caused a Malaysia Airlines 777 to stall, by slowing its airspeed from 270 knots to 158 knots and putting it into a 3,000ft climb. The pilot prevented disaster by disconnecting the autopilot and pushing the nose down. Another glitch last year caused a 777 to lurch to the right over the Atlantic. The captain had to quickly disengage the autopilot.

As BA’s stricken aircraft was moved to a hangar yesterday, other hypotheses were being aired. One was that a “bird strike” had shut down both engines. The impact of large birds hitting the fans inside the engine can cause damage, but no witnesses noted seeing flocks of birds near by. Another theory is that water got into the fuel.

The preliminary report from the AAIB into the incident is expected to be released in 30 days."

http://business.timesonline.co.uk/to...cle3221901.ece
Doubtfull!

Pure Speculation.... Wait for the investigation report!

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Old 01-24-2008, 02:42 PM   #3  
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The AIB now, apparently says that that neither engine failed. One had a thrust reduction after the A/T commanded it to increase power, and the other followed suit 8 seconds later. The S turn at about 1000 ft is pretty funny as well (as described in the news papers so I'll leave that one open). I'd like to see the configuration and the speed just prior to 1000 feet if that is in fact the case. There are times when one might want to hold the power levers back as the A/T commands more thrust. Flap being selected just prior to airspeed getting to command airspeed for the previous flap setting, so the aircraft continues to decay speed as late flap is selected by the crew. I wonder, as the AIB keeps saying about the A/T commanded thrust, it was initially added but soon thereafter decayed; well, it sounds like the scenario that I just described, but finger trouble missed one of the power levers, retarded it it 8 seconds later, and physically held it there. The flight director would have favored path over speed at that point if the G/S had been armed and intercepted.

My question for the geniuses is this; if the power levers were retarded by the pilot flying, would the DFDR show an A/T commanded thrust increase if the power levers were physically over- ridden?

If the papers are wrong, and they often are, and there was no S turn or parallel of the LOC, then perhaps it could have been some sort of fuel contamination, or a lot of birds. But, both engines were spinning above flight idle to the ground (latest from the AIB). The eye-witness reports saying that it got 'very loud' close to the ground would indicate a late application of max power. But again, I know, eye witness reports are often the opposite of the truth. Maybe they were hearing the bogies removing the tops of the approach lights.

So, we all fly planes, if not B777 then perhaps something similar (Your C421 and many ****-pit videos count in my book). This affects us close to home so I think candid conversation, which generally includes 'educated' speculation shall we say, is perhaps prudent. I haven't seen the plane spotting nightmare of idiocy that is on that 'other' web site over on this one, so why not?

Sorry Whale, but we are all slaves to speculation. I agree to a point and apologies for my candor; I just can't help myself. I guess I could sum up my feeling's by saying that I have no problem, in the least, with going to work this afternoon in my shiny RR Trent powered B777. Something is just is not adding up here (I do hope it was birds).

Last edited by KoruPilot; 01-24-2008 at 02:49 PM.
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Old 01-24-2008, 02:44 PM   #4  
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And can I go out on a limb and mention that the Malaysian debacle just might have been due to a lack of paying attention, or understanding of the FMA's.

I'll save my 'We have become slaves to the automatics' speech.

Your welcome.
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Old 01-24-2008, 08:57 PM   #5  
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Excerpt from BBC story:
************************************************** **************
When the automatic throttle demanded more power, the engines initially responded. Then first the right engine, followed eight seconds later by the left, powered down - to a level below the thrust needed.

Warnings would have flashed up on engine monitoring screens in the centre of the control panel, showing the power was below that required.

A lower screen would have shown more detailed information about the flow of fuel around the aircraft. The primary displays would show the likely height the plane would descend to in the next minute.

Faced with the knowledge that a disaster was in the making, the crew had around 40 seconds to save their aircraft. It's understood the captain Peter Burkill quickly reduced the amount of wing flaps deployed.

This was as important as the skilful manipulation of the control column by John Coward, in saving the aircraft. It cuts drag, speeds the plane up a little, and when a pilot has speed, he can maintain altitude.
************************************************** ***********

What the @%#$? over. Where do they get this stuff? I don't know about BA, but we, as is Boeing practice, have the lower EICAS blanked for take off and landing. If there is a problem it will come up.

At any rate, would you raise the flaps with low airspeed on short final? I think if the plane was behind the curve then lowering the flaps would reduce drag yes, but also reduce lift; The thing would sink quicker at a lower speed. I'd guess blow-back but the pilots, and the AIB are saying that they saw the lack of power and moved the thrust levers manually, so they must have been at a reasonable speed or the power levers would not have advanced.

Has anyone else seen anything regarding maneuvering close to the ground on final? I have just heard the eye-witness accounts.

Last edited by KoruPilot; 01-24-2008 at 09:22 PM.
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Old 01-24-2008, 09:02 PM   #6  
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And to top it off they spelled skillful incorrectly.
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Old 01-24-2008, 09:37 PM   #7  
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Damn Windows Millenium
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Old 01-25-2008, 08:27 AM   #8  
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Quote:
Originally Posted by KoruPilot View Post
... well, it sounds like the scenario that I just described, but finger trouble missed one of the power levers, retarded it it 8 seconds later, and physically held it there. ...
how do you "miss" a power lever on a two engine airplane? sounds like a plausible scenario on a 4 engine airplane because ive seen it and done it, but seems out of the question for only 2 levers.
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Old 01-25-2008, 03:57 PM   #9  
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I was at LHR waiting for my flight to JFK when the 777 landed short. My flight was delayed so I ended up going into London for a few hours.

Last edited by jsfBoat; 01-26-2008 at 10:52 AM.
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Old 01-25-2008, 04:07 PM   #10  
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Did you see the pictures?
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