The suicide hypothesis is by far the likeliest.
Just google the words "suicide" and "disappear". It's not as weird as people seem to think.
Murdering 230 others in the process is also not unprecedented.
The likeliest hypothesis: he put that plane down gently in the roaring 40s, a la Sully in the Hudson, opened an aperture (say by lowering the landing gear, or similar) and then killed himself, maybe via a pill.
The plane would be at 16000 feet below sea level, with no debris.
Last edited by ensco; 23rd Mar 2014 at 03:26.