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Plane lands short of runway.

  1. Jan 18, 2008 #1

    Art

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    A Boeing 777 crashed yesterday at Heathrow apparently due to engine failure
    http://uk.reuters.com/article/domesticNews/idUKHO86894720080119?pageNumber=1&virtualBrandChannel=0

    In the event of catastrophic engine failure wouldn't it be normal for Boeing to issue instructions for safety checks or even ground other 777s until the cause was found?

    Boeings lack of reaction and the fact there was no fire makes me wonder is it possible the plane just ran out of fuel??
     
    Last edited by a moderator: Jan 20, 2008
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  3. Jan 18, 2008 #2

    Evo

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    We probably won't know for awhile.
     
  4. Jan 19, 2008 #3
    It might also be a problem related to just RR engines and not anything with the other subsystems of the airframe. The trip 7 also uses P&W and GE engines. If it was found to be a problem with just the RR engines only the models using the RR engines would have to be grounded. However since it was only with one plane and no life was lost so far I believe it is up to the individual carriers to decide if they want to inspect/ground there 777s.
     
  5. Jan 19, 2008 #4
    No. The airplane was no where near out of fuel (All flights have at least an hour reserve). It could have been fuel starvation, or a software error. The engines were running, they just didnt spool up. Thats not lack of fuel. This wasnt "catastrophic engine failure". It was an engine failure.

    I would bet on a software error (777 is all fly by wire).
     
    Last edited: Jan 19, 2008
  6. Jan 19, 2008 #5

    Garth

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    One report in our newspapers said they lost avionics as well.

    Both engines and avionics?

    It must have beeb a computer glitch, and yes Boeing ought to ground and check all the 777s until the cause is established.

    Garth
     
  7. Jan 19, 2008 #6
    I certainly hope that you are right. There is a tendency to have systems like that redundant. The F-16 for instance has 4 identical flight control computers, three of them operating directly, while the three signals are continuously compared. As soon as one signal is deviating, it is kicked out and the fourth system is included. What can go wrong?

    Well, we lost an aircraft because the wiring of all the systems had the same routing and an electrical short cut damaged the wiring of all four systems.

    So if two engines don't respond simulaneously, given the control system reduncancy the amount of probable causes is very limited and would not exclude fuel starvation for whatever reason.
     
  8. Jan 19, 2008 #7

    Garth

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    One factor was that below 600 feet warning signals are suppressed to avoid distracting the pilots on landing.

    As a consequence the pilots didn't know they had a problem until the co-pilot John Coward noticed they were losing speed.

    Perhaps this is what they meant by "losing avionics".

    I would have thought that when approaching a landing there were certain warning signals that you actually would want to hear, such as: "You've lost your engines!"

    BTW, as a point of information, they had 10 tonnes of fuel left on landing.

    Garth
     
    Last edited: Jan 19, 2008
  9. Jan 19, 2008 #8
    At 600 feet and at least 150KTS, a warning signal is a pointless distraction. You are too low, and there is no time to do anything about it.

    What would 'your engines wont spool up' do in that situation? Absolutely nothing.
     
    Last edited: Jan 19, 2008
  10. Jan 19, 2008 #9

    wolram

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    I guess the only alarm needed at that height is a stall warning or terrain warning.

    How is the flying going Cyrus?
     
  11. Jan 19, 2008 #10

    Astronuc

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    http://www.cnn.com/2008/WORLD/europe/01/18/boeing.causes/

    Boeing is apparently providing technical assistance, but they probably won't know much until they check the flight recorders - black box.

    It could be a software or hardware/component failure, and they'll look at human factors as well.


    http://news.bbc.co.uk/2/hi/uk_news/england/london/7197506.stm
     
  12. Jan 19, 2008 #11

    Garth

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    One thing that will be examined in the investigation will be whether the pilot could have reacted more quickly, which just might have bought more time to adjust the glide path.

    A warning signal could well have been useful and not a pointless distraction.

    As it was, the engines were throttled back for landing so the fact that they had failed was not noticed until the pilot saw the air speed was dropping. The controls began to vibrate which told him he was approaching a stall.

    When he found he could not get any power from the engines he put the nose down to gain flying speed.

    In doing so he lost valuable height which resulted in him landing short of the runway, fortuitously not too short. (I used to live about two miles down that glide path!)

    Garth
     
    Last edited: Jan 19, 2008
  13. Jan 19, 2008 #12

    Art

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    Watching the pilot being interviewed he said there was no power from the engines whatsoever when he landed. What could cause 2 engines to fail simultaneously other than a fuel problem?
     
  14. Jan 19, 2008 #13

    Astronuc

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    Loss of avionics such that the throttle didn't respond.

    It almost seems like the cockpit controls (or the part that includes the throttle) were disabled! In that case, there is nothing the pilot can do. He might have been able to pull the nose up to gain lift at the expense of forward airspeed, or reduced flaps with an increase in pitch.

    As far as the pilot goes, he doesn't have a lot of time to understand and act when the plane is at 180 m and 3200 m out. Presumably something would have indicated that the plane was below the glide plane.

    At 150 kts ( 77 m/s) the pilot had 41 seconds to impact - not a lot of time to understand the problem and take effective corrective action.
     
  15. Jan 19, 2008 #14

    Garth

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    I agree with Astronuc; there were two independent fuel tanks and supply systems feeding the engines individually.

    It would seem the height of bad luck to lose both simultaneously!

    Garth
     
    Last edited: Jan 19, 2008
  16. Jan 21, 2008 #15
  17. Jan 21, 2008 #16

    Astronuc

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    I posted this additional information in the Air Crash thread in the Mechanical and Aerospace Engineering forum.

    http://aviation-safety.net/database/record.php?id=20080117-0

    http://www.aaib.dft.gov.uk/latest_news/accident__heathrow_17_january_2008___initial_report.cfm


    Interestingly, there was a problem with the 777 in Australia.
    http://www.airlinesafety.com/faq/777DataFailure.htm

    I wonder if this failure had any commonality with the BA038 problem.

    Until the flight recorders are analyzed, it's too early to tell.
     
  18. Jan 21, 2008 #17
    There is the possibilitity of engine icing but that requires quite a set of adverse conditions to be met.
     
  19. Jan 22, 2008 #18

    chroot

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    This is absolutely false. Instrument landing system decision altitudes are generally no more than 200 feet above ground level. Pilots routinely fly approaches down to decision altitude in zero-visibility conditions and conduct missed approaches from that altitude. Even at 600 feet above ground, with visual contact, the pilots would have had plenty of time to change their minds.

    - Warren
     
  20. Jan 22, 2008 #19
    Warren, the engine was not spooling up at 600 feet. What could he have possibly changed his mind about? Was he going to do a go-around with no power?
     
  21. Jan 22, 2008 #20

    chroot

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    If the aircraft already has its flaps fully extended, and is losing airspeed to the point that it may stall, retracting the flaps will result in an immediate stall. The point of the flaps is to allow slow flight (or add drag in situations where it is desired). Pulling the nose up would also result in an immediate stall.

    Again, 600 feet actually gives the pilot plenty of time to make decisions, if the aircraft is operating normally.

    - Warren
     
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