My dad's a retired air traffic controller and was working the night of the Pan Am disaster.
He said that it couldn't have been an explosion that was missed on the radar as the "bing" gets bigger as the debris is thrown across a huge area. So, you couldn't miss it.
That's how they knew that there had been a bomb and not an engineering failure when their plane vanished off the radar.
He also said that here the military and civil air traffic controls work together in the same room - so information is exchanged freely. That doesn't happen in Malaysia, so, that's why it took several days for any sort of communication between them.
It's a dreadful siutaion, hope answers appear soon.