The captain flew it to the back 40, performed a belly landing and sank it mostly intact. The passengers were already dead and buckled in from the 45k’ climb that starved them of oxygen when the packs were turned off. They won’t find wreckage on the surface.
OR
Its in a hangar somewhere
I would offer this scenario. Pilot has master plan to land in some “Stan” republic. Minutes before final radio contact, he’s started the plan, and co-pilot has weapon of some type on himself. Pilot tells co-pilot to input these turn-points and direction...mostly grinning over how easy this whole thing is.
Co-pilot puts in turn-points, except on last one...instead of north....puts south. Final radio contact, if you notice...co-pilot is the person talking, but never identifies himself or repeats what the controller had said. Generally, that would violate two taught standards of all pilots, and I think the young co-pilot knew the threat already.
A fight ensues...both mortally wounded, but the pilot is no longer able to stand or get into the pilot’s seat. Plane goes to high altitude and kills everyone onboard. Auto pilot is on, and carries out the directions of the co-pilot. Plane runs out of fuel. Jihad Joe and his friends at the Stan republic runway sit for four hours after the anticipated landing, then figure something bad happened to the plan, and leave.
No need to brag about this...because you’d like to repeat the episode again. Unless you find the plane, and find both guys with serious wounds in the cockpit....you will not be able to prove any of this. End of game? Wait for next game.