The story that I have heard from a couple of people and read on a few aviation sites where pilots hang out is that the problem stemmed from a thrust reverser unlocked indication on one or both of the inboard engines (#2 and #3). The thrust reversers are the gizmos that direct the engine thrust forward on landing to help slow the plane down.
Anyway, apparently the thrust reverser on at least one or maybe both of the inboard engines, the ones nearest the fuselage, erroneously indicated “unlocked”—that is to say, not deployed, but not locked down in a correct state—as the plane took off. There is logic in the electronic systems on the 747-400 that when the inboard thrust reversers unlock, the inboard leading edge slats on the wing retract; this is to keep debris kicked up by the reversed thrust from getting into the internals of the slats. Here’s the catch—theoretically, the thrust reversers cannot unlock and deploy unless there’s weight on the main landing gear wheels. So there’s no redundant check on the slat retraction; the 744’s brain sees unlocked thrust reversers, assumes the plane’s on the ground since the reversers are unlocked, and retracts the inboard leading edge slats.
Those slats are basically flaps on the front of the wing. They provide a substantial boost in lift during takeoff and landing. Retract those, particularly right at liftoff from Johannesburg, which is 5500 feet above sea level and often very hot (which reduces lift), and suddenly you’re in a world of hurt. The crew was very close to stalling the airplane only a few dozen feet off the ground, and by then, they’d probably run out of runway—fully loaded 747 heading for Heathrow, a mile above sea level, on a hot day, means using a LOT of pavement just to waddle it into the air.
BTW, I wouldn’t trust ANYTHING about aviation from the Daily Mail. Last year when the Spanair MD-82 crashed on takeoff from Madrid, they published alleged sensational photos of the “doomed plane’s takeoff” with “an engine on fire”...turns out it was a different Spanair MD-82, on a different day, and it was a perfectly normal takeoff with a perfectly normal amount of exhaust smoke from the engines.
}:-)4
That was quite an explanation-thanks
Shouldn't the slats retract when the thrust reversers are locked(deployed) ? From what I understand the thrust reversers are deployed shortly after the wheels touch the ground, and I guess the slats and flaps also retract around then to reduce lift and transfer as much of the weight onto the wheels to aid in braking.