Your math is off, 500,000 tons is 500KT. .5KT is 500 tons or 1 million pounds. Combine the weight of the jet, the stored energy in the fuel and the speed of the aircraft and you can easily reach this energy level.
No. 5 kilo tons is 5000 tons... of conventional high explosive, or TNT. Jet fuel is no where near as explosive as TNT.
Combine the weight of the jet, the stored energy in the fuel and the speed of the aircraft and you can easily reach this energy level.
No, you really really can't. Sorry.