AF 447 Search to resume

[mm43]

Having thought a bit about how an "intact" hull would react on impacting with the water in the following configuration:-

Pitch Attitude +5°
Bank 0°
Rate of Descent 9,120 ft/min (90KTS)
Ground Speed 50KTS
Heading +10° relative to direction of flight probably in a flat spin clockwise

Initial contact of the empennage would have caused a rapid reduction in pitch, the engines (if still attached) would bite into the water, and as the main wing span impacted, the g forces between the engines and their pylon mounts would have resulted in them shearing off and heading straight down.

Deformation of the empennage and the fuselage aft of the wing will have resulted in a vertical fracture at this point, and similarly to the fuselage forward of the wing. These fractures would have opened fairly cleanly as the result of impact g forces rapidly reducing to zero, then followed by the reciprocal moment due to initial buoyancy and the water rebounding and overshooting its original level before dampening down over a few more cycles. The forward, middle and aft sections of the fuselage all acted differently, with the largest g forces being sustained by the wing section, due to its much bigger volumetric area.

If you need a little help in imagining this, then get a small round plastic pill bottle, add about third of it's volume in soft brown sugar (gets rid of any free surface effects if water is used) to it and replace the cap. Lay it on its side, tap it to ensure the sugar settles along its length, then drop into a bucket / bath etc.. of water on its side and watch what happens!

This accident bears no relationship to the Ethiopian 767 ditching in 1996, where forward moments were reduced by the left wing slicing into the water first, catching a coral reef, and the aircraft rolling and breaking up in the swell.

The point I am making in respect of AF447, is that hitting terra firma in the configuration described above, would have resulted in an impact crater, major disintegration of wings and fuselage followed by fire. This didn't happen, and the reciprocal moments generated by this sort of impact with terra oceania need to be taken into account when discussing the manner in which the vertical stabilizer could have left the empennage anchor points. Not to put too finer point on it, the seat belts didn't cause the damage they are reported to have done due to the impact acceleration to zero, but the substantial reciprocal moment caused by the sea and initial buoyancy, will have. Just think of being belted in on the wrong side of a slingshot that had been tensioned down, then released.

mm43