Originally Posted by grity
but with decreasing speed during climb no longer every energie of the turbines is required against air drag, so they provide more energie into the kinetic system....
That is why my initial calculation was based on zero speed with a delta. I used the fact that the plane was in a stable state with respect to power and drag. Then I calculated an energy tradeoff for the change in altitude. Admittedly this is at best a first approximation. Nonetheless, that was not accepted around here. Either calculation has a reasonable chance as a first approximation to what happened. The plane was in heavy turbulence moving through chaotic winds.
Above I mentioned it may have received stick up in response to a down draft, the plane then moving into a strong updraft and surprised PF. The chaotic winds they were going through may preclude a really accurate assessment of the energy tradeoff. It is suspicious that the number comes out so close to what was apparently observed.