[GreenHornet]

It is quite unusual that there would be no distress call, especially when the plane was cruising at altitude. Because of this, I immediately thought terrorist act. A lot of muzzies in that part of the world.

I thought the same thing. If it had been a mechanical malfunction, there would have been some time for the crew to react and send a distress signal.

[LiveFreeOrDie2001]

...and there would have been things floating in the water if it was a mechanical failure.