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Old 26th Aug 2008, 17:46
  #973 (permalink)  
justme69
 
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Please, note that the airplane, after touching the ground for the first time (reportely moderately hitting it with the right wing first) is said to have bounced up and down (possibly meaning that all wheels left the ground) at lest 6 times and "use" another aprox. 500m of terrain until it "exploded".

Imagine this scenario.

1) Pilots rotate unaware that their configuration for take off is wrong (i.e. both slats not correct, flaps angle insufficient, etc). Perhaps warning signs of incorrect slats/flaps were disminished by the result of the first call to service (i.e. airplane was in air/ground mode, alarms disconnected inadvertly, some other malfunction, etc).

2) Pilots don't take much action although rotation lasts for a bit longer than it should. Maybe they figure they were a bit heavier than they estimated or tail wind was playing them up a little. They are after V1 anyway and can't figure out anything wrong (yet). Their nose angle is a bit off.

3) Airplane takes off. Stall warnings come up as soon as ground effect is over. Perhaps some of the alarms didn't work properly for the reasons stated above or unknown. Airplane starts an uncontrolled roll for random stall conditions.

4) They concentrate a bit on controlling the roll which delays their action of nose-down, flaps-15, max throttle. Their reaction is perhaps late because the aureal alarm didn't sound and only the shaker indicated the stall plus they had to control the heavy roll "first", unsure of the stall warning being real. Perhaps they even decided to (or accidentaly) "pull up" a bit as first reaction (against training, but after all, they were taking off and "pull up a bit" is a natural first reaction if you are falling and you want to go up).

5) The airplane touches the ground, barely hitting the wing first, but off-course. But the pilots already commanded full throttle, lowered the flaps/correcting slats, and are already nose-leveled, but a few seconds too late to recover from the slightly low V2 speed and heavy weight. Some mechanical damage is sustained from the fall, as it was above max landing weight (fueled-up/heavy/harsh 15m stall fall) plus the wing touched ground. The pilots may have suffered some injuries too.

6) Now the airplane "recovers", starts accelerating again, and has good wing configuration, but rotating is hard (landing gear may have problems, airplane might be off path on the landing strip, etc). The airplane bounces around a few times, wheels leaving the ground briefly, but not quite (bad nose angle, weight, other control problems). Just a couple of seconds after the full throttle was commanded and perhaps even before the engines could start to truly perform (low air density), the pilots decide to abort.

7) They try to deploy reversers, brake, partially or fully successfully. It's too late. The airplane has even accelerated a bit, and after 3 or 4 more bounces, it hits obstacles at very high speed.

A million different things could've happened. Some more likely, some less, some way less/almost impossible. But such complex scenarios, as the one described, without one major clear-cut cause, is going to have to be widely speculative and therefore of little value since only hard-evidence (FDR) can (dis)prove it.

We'll just have to sit and wait for the official investigation, hope it can shed enough light to find a very likely cause(s) and a way to improve a solution.

Last edited by justme69; 26th Aug 2008 at 18:00.
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