Originally Posted by
WatchTheSkies
The first 20 sec of the data is the left turn. I assume the aircraft became inverted as it explains the lateral speed increase and heading direction changes. When the plane is inverted, it was still turning left relative to itself, right if you are viewing the upside down plane from the ground, producing the +10°/s increase in heading
I tend to agree with your guess that the aircrafts initial departure from normal flight was a left bank past 90 degree with an increasing nose down (relative to the horizon) attitude.
We will soon get the answer when preliminary data from the flight data recorder are released.