intact airplane. something like at least the tail and the wings. the tail being important because that's where the black boxes are. >> you're confident they're right -- that fifth ping had nothing to do with the plane, right? >> i wouldn't say confident on that. again, i'm hopeful. it is the right signal. frequency. and the pulse rate is -- makes me very hopeful that, indeed, it's a pinger from the black boxes. >> the first four pings that were detected, one lasting for about two hours, one for 15 minutes, the third and fourth, five or six minutes each, they had a frequency slightly less than the 37.5 kilohertz and it lasted a little bit, tiny little bit more than one second each. are those significant changes or are they the real thing? >> i wouldn't say they're significant. that may have helped really to