right track. but they need to continue the work. and if for some reason they can't find them, it will make the search effort much more complicated and team consuming. >> so what do they do? i know from time to time they reassess, reexamine the data, reassess the search area, redefine it. have they made a contingency plan if they don't relocate the pings? >> reporter: there is a plan. there is other technology on board specifically that blue fin 21, the yuunderwater submersibl which scans the ocean floor. but they're not ready tonology . one day's work for the tow pinger locater, it would take a full week for the underwater submersible. and it takes two miles to get down, 16 hours at the bottom and then another two hours up. so you're talking about a significant amount of time for just the fraction of the result.