So I'm thinking we're pretty close to saying that the flight has been "stolen" rather than crashed.
Flight 'disappears' at the exact point it hands over to the Vietnamese. Aircraft seems to have taken a turn only an experienced pilot could make and headed in a completely different direction, flying in a manner making tracking much more difficult. Aircraft is recorded in the air for 4-5 hours after it disappeared, flight is thought to have passed through a number of waypoints suggesting conscious and planned navigation by an experienced pilot. No wreckage has been found. Remove any number of these points and you've still got too much for coincidence.
Lots of people in lots of capital cities will be getting very little sleep for a while.
Flight 'disappears' at the exact point it hands over to the Vietnamese. Aircraft seems to have taken a turn only an experienced pilot could make and headed in a completely different direction, flying in a manner making tracking much more difficult. Aircraft is recorded in the air for 4-5 hours after it disappeared, flight is thought to have passed through a number of waypoints suggesting conscious and planned navigation by an experienced pilot. No wreckage has been found. Remove any number of these points and you've still got too much for coincidence.
Lots of people in lots of capital cities will be getting very little sleep for a while.