the last two hours of voice transmission in the cockpit. the flight data recorder records a lot further back than that. the next step will be sending down a r.o.v., a robotic submersible that this is a work class rov. it is industrial strength if you like. able to bring back quite large pieces to the surface. if you get the black boxes, you don't usually need to go back too much further with forensic examinations. >> what if they don't reveal everything? like i said, this flight flew on for more hours than usually, i guess the cockpit voice recorder usually records. david, correct me if i am wrong here, is there is a possibility that the black boxes won't have all of the data on it and what if it doesn't? what will they do then? >> i have been hesitant to bring this up previously. when we talk about the flight