[teamonkey]

From what I understand, what makes this (probable) crash unusual is that nothing was received from the plane. Modern airliners send out all sorts of signals over several channels. The data that sites like FlightTracker uses are part of it.

In the case of the Air France crash, telemetry data was sent out in the good 15 minutes it took to go down. With this flight - nothing. One moment it was sending data saying all was well, the next it simply disappeared from the screens. Extremely unusual. If there was a sudden disintegration of the aircraft, there's a good chance an internet-based device would go offline too.

I believe the black box has a signal that will let it be found but it only has a range of 1-2km - less underwater.