Originally Posted by
airtren
A kinetic versus potential energy conservation calculation shows that the BEA indicated height delta (2500 ft from FL350 tgo FL375) checks against the BEA indicated delta speed of 60 knots (from 275 to 215 knots). Same is true for FL380, and 185 knots.
dEk = Ek (275knots) - Ek(215knots) = dEp (2500ft)
Not wanting to nitpick, just for the sake of correctness, it has to be noted that the 275kts and 215kts were IAS.
For any kind of energy calculation you have to take TAS.
In this case that would be approx. 495kts and 390kts, repectively.
Edit:
This corresponds to ~4200ft but is still very well explicable by the increased drag of the maneuvers. So I don't contradict the statement that the kinetic energy figures are plausible.