I can’t figure out a scenario that makes sense. If it flew 4 hours with everyone unconscious, it still doesn’t explain how the transponder was shut off manually in the cockpit.
I come up with a new theory every day. I’ve had this one for a few days:
Terrorists get into cockpit and turn off transponder. They turn west, headed to Somalia or some other mid-east hell hole.
And run out of fuel, because the plane was only fueled for a 5 hour flight to China.
And, for unfortunately not the first time, terrorists inadvertently ditch an airliner into the Indian Ocean.
Shhhh, you’ll spoil the cover story!