Originally Posted by Dutch M
Where did the Ekin of (458 - 0.03) m J go ?????
Nowhere. You changed frame of reference. You can't do that when calculating energies unless you take account for the different energy states of the frames of reference.
The glider that lifts and sails backwards relative to the ground is not trading velocity for height. The wind against the glider that is moving at a different rate generates both lift and drag. Those are forces which will change the glider's energy picture relative to its starting point. Rigorous application of forces and frame of reference can tell you what the plane or any other object is going to do.
Without considering the external forces you're hand waving. And, yes, we were hand waving to get a feel for what an ideal energy exchange would give. Once you add the external forces applied to the plane you can account for some discrepancies. If you include enough of the known forces you can deduce what additional force must have been applied to get the final result.
If I knew what climb rate to expect from a 10 degree angle of attack we could probably deduce whether or not there was wind speed, relative to the ground, working to alter the aircraft's energy profile. On doing an obvious estimate (rather than exact math) the plane was moving upwards at something around 80 MPH when it was going 7000'/min. So that motion is slow enough external winds could have been a factor. The climb rate expected for the plane's condition would nail this down a little tighter. And the wind itself would impart forces on the plane which would change it's apparent energy profile.
But, first, keep everything in one frame of reference. As soon as you change frames everything gets all gooey and slippery to think about. It's also best to consider a nice conceptually solid frame of reference so that it's easier to think about what's happening. Referencing the air mass is tricky because it's a changing reference.