Quoting from HazelNuts from way back last August (hope he doesn't mind)
'So, based on the ACARS messages alone, the ROD in the final seconds could have been anywhere between 2463 and 16320 fpm, while the average ROD in the preceding descent was of the order of 7850 fpm: 35000 (2:10:10) - 2176 (2:14:21).
I also believe that the airplane probably stalled one or more times in those final minutes. Is it certain that it was stalled in the final seconds?
Quote:
some juggling of a flight termination time could give a v/s that fits with the BEA reports (high vertical speed, 'en ligne de vol', and 'arm 36 g' etc..).
The 320 ditched in the Hudson at 780 fpm, 125 kt, 9.5 deg pitch. Its fuselage received substantial damage but stayed in one piece.
The Turkish 737 in Amsterdam impacted stalled at 3000 fpm, 100 kt, 22 deg. pitch, its fuselage broke into three sections.
AF447's stall speed (Vs1g; V_alphamax) was 158 kCAS; 162 kTAS; 274 fps. The corresponding alphamax can be estimated as 14.5 degrees. Interpreting "avec une assiette positive, une faible inclinaison et avec une vitesse verticale importante" as 2.5 degrees nose-up, leaves an FPA of 12 deg. down, or 3418 fpm.
So was it stalled?'
Based on straightforward kinematics, an impact at 20000m from LKP within 300 seconds assuming constant ROD gives an average ground speed of about 140 kts, about 65 kts vertically, flight path angle -26 degrees, average speed about 170 kts and with linear deceleration gives a starting speed of 340 knots.
Are these figures that unlikely ?