I think we have agree to rule out that any of the problems affecting this situation resemble an emergency.
It can only be flagrant sabotage, or a blunder compounded by savage incompetance.
Either they fucked up so bad that they didn't just shoot themselves in the foot, but instead blew their whole leg off. Possible with hypoxia scenarios.
Or someone sealed the fate of that flight in cold blood. This version narrative includes the premise of suicide, including single-handed, lone wolf pilot suicide, although other nefarious possibilities fall under this umbrella.
The predominant fact of the outcome is that they flew so far off course, and without any distress signals, that their ultimate fate passed into history as a near total enigma which essentially requires strenuous effort or fantastic misfortune.