From the "published" data :
At 23:16:52, ground speed was ~470 kts, that is ~242 meters/second.
At 23:17:29, ground speed was ~311 kts, that is ~160 meters/second.
So, in 37 seconds, the horizontal speed went down by ~82 meters/second.
This is a 82/37 = 2.2 meters/secondē deceleration. So, in the plane, the apparent vertical was tilted about 13 degrees (arctangent(2.2/9.8) = 12.6). A 13° tilt upward of the plane might be felt as no tilt and constant speed... If the captain was standing up, playing with the breakers, he might be not aware of the trajectory problem until the plane began to fall.
IMHO.
Last edited by Shadoko; 2nd Feb 2015 at 03:45.