Afriqiyah Airbus 330 Crash

[andrasz]

Originally Posted by valvanuz

I cannot understand how the two wings would manage to be at the front end of the crash without any big other pieces around.

The following are all FACTUAL information, verifiable from information and linked photos over the previous 650 or so posts:

• The ground contact marks indicate the aircraft hit the ground tail first in a nose-up attitude
• The first major piece of wreckage is the tailplane with all three control surfaces attached and (relatively) intact, facing the opposite direction of travel, about 200 metres from initial impact.
• The last piece of wreckage are the wings, both still attached to the central wing box, structurally largely intact except for destruction by the post-crash fire, located about 700 metres from the initial impact point
• The fuselage is shattered to tiny bits, littering the area between the tailplane and the wings in a narrow 500m long wreckage path
• At least one engine was producing thrust at time of impact (2nd stage compressor blades show clear FOD)

Without speculating on the why's, I believe the last (rather disturbing) moments of the aircraft and the impact sequence can be DEDUCTED reasonably well from the above information:

1. Aircraft strikes the ground with the tail in a strong nose-up pitch attitude. The impact is strong enough to fracture the rear fuselage, and the tail breaks off.
2. The forward momentum (and possible impact rebound) carries the fuselage up and forward (probably aided by TOGA thrust, with the associated pitch-up moment countering the pitch-down moment caused by the loss of the tail for a few moments). While this is happening, the tail tumbles on the ground (attested by the damage on the tip of the V/S) one or more times, and comes to a rest facing rearwards
3. Loss of tail results in a rapid pitch down of the remaining fuselage, hitting the ground in a sharp nose-down attitude, probably pushed by the engines at full power.
4. Nose and front fuselage is crushed and fragmented, while the whole structure pivots around the ground contact point, propelling the still intact wings forward. The crushing of the forward fuselage cushions the impact sufficiently that the wing structure remains intact. The engines would still run at this point (for another few miliseconds) ingesting gravel and aircraft debris.
5. The wings tumble over, crushing the remaining fuselage over and aft of the wing and probably losing the engines at this point. This would be the point where fuel tank integrity would be lost, producing a fireball of vaporized fuel, moving forward together with the wing structure. (this explains the lack of major fire in the earlier part of the wreckage path)
6. The remaining momentum causes the wings to tumble over once more, coming to rest facing the original direction of travel, and are partially consumed by fire fed by fuel remaining in the wings and centre tank.

This whole sequence would have lasted 8-9 seconds if initial impact happened close to the 135kt approach speed, less if applied go-around thrust already increased speed significantly.