We can shed more light on this question if we change the scenario slightly. Image the aircraft is climbing from msl at 250 Kts TAS and 5000 fpm when the parrots take off. After 8 minutes the aircraft is at 40000 ft, and still at 250 kts TAS (just ignore the very low CAS for now).
Each of the parrots has acquired 40000 foot parrots of potential energy (these are of course not the same as parrot feet of which each parrot will have only two, regardless of height above msl). Each parrot will however still have the same kinetic energy (1/2parrot x TAS squared). Was that extra potential energy derived from jet A1 or from parrot food?
Now consider what happens if the aircraft then gently enters a descent at 5000 fpm still at 250 Kts TAS. When it gets back to msl the parrots have lost all of their potential energy but still have the same kinetic energy. By what means did the parrots get rid of the potential energy?
Last edited by Keith.Williams.; 11th September 2002 at 19:33.