[phumbe]

> Gravity alone is unlikely to be able to accelerate a plane like that in such a short time

Yeah, a quick (and very elementary) back-of-the-envelope energy calculation shows that gravity alone couldn't achieve that speed. [SEE EDIT]

> Were the pilots desperately trying to go up, not knowing which way was up?

We'll have to wait and see, but it was morning, and I think I heard that there was weather in the vicinity of the crash but not at its actual location.

EDIT: That calculation was wrong. The aircraft had more energy at 5475 ft than it did at 3200, 7.73 seconds before the last data point.