the sea floor, buried in aircraft wreckage that obscures the signal. and it assumes that vessels looking for it are within range of that acoustic beacon. >> how far away can they be? >> i think it depends on the conditions in the ocean, how deep it is, and whether there's a thermal layer, temperature gradient that might channel the acoustic signal away from the surface, it's hard to say, but probably tens of miles if it's not buried in wreckage or the sea mud. >> do you agree that it must have been something catastrophic that happened quickly? >> i think all indications are that it was something catastrophic that happened quickly, we just don't know yet what it was. and we probably will not know until the wreckage is found and the recorders have been recovered and analyzed, hopefully they'll provide useful data about what was said and done on the cockpit in the cockpit and what the flight parameters were in the moments leading up to this event.