search, 128,000 square mile area, this might not be the right location? >> this the thing. we really don't know. until we find something clearly tagged back to the aircraft, we don't know i have faith in the people that have been running retro navigation exercise with the handshake data. obviously that steered them down to this corner of the world. i trust in those people, the technical abilities. at the moment that's all we've got to go on. >> the use of this u.s. pinger on an australian ship, we've heard many experts say you've got to be on top of an impact zone, on top of where this tail where the pinger and flight data recorder located in order for it to be used. is it your feeling perhaps a secret of surveillance has