Problem with the theory: It appears the turn towards the west had been programmed in ahead of time...before the last voice communication where he said everything was OK.
So it was a premeditated deviation off the flight plan...and voice comm was made AFTER that.
If the above facts are accurate (and they are as of this morning)...then the theory of a fire and then a turn to the west....and the crew being overcome is blown.
Yeah, it’s still a confused mess. If the report is true that he had made the turn west before the last voice transmission, my experience with air traffic control is that they would have been all over him asking what he was doing, not handing him off to Vietnamese ATC.
This is an informational mess.