by a continuous moving flow. they can move a long way but hopefully they are not moving into tar. >> they say it's too early to send a submarine to aid in the search. even when you stick listening devices into the water, they can only listen for maybe one or two miles. you need to zero in on the debris field more. talk to us about the equipment that they would use so you can guess more intelligently as to where the actual plane is. >> well, if they find -- if they hear a ping from the transponder, they will deploy autonomous undlerwater vehicles auvs. if they locate the wreckage, they will come in with r.o.b.s, tethered vehicles that can go down and recover the black boxes hopefully. >> that's interesting. i've seen some of those images