If the autopilot is flying the thing into the ground on a smooth, uneventful path, AND the software is reporting level flight at constant altitude to the pilots, what would clue in the pilots that something is wrong?
Lets see... I went from 38,000 feet to the ground. I’m below the clouds now instead of above them.... If I look out the window the ground sure seems closer..... Someone has me on radar somewhere and has probably called to ask why I’m not at 38000 feet? Is the altimeter a piece of software on an airbus? Of course if I’m asleep I’m clueless. OR if some terrorist has cut my throat there is not much I can do then either.