in the morning it was 3:30 in the morning on their body clocks. >> there were four pilots, that's for safety reasons? >> absolutely for safety reasons. >> they can get some rest and they're not required to be awake the entire time, so somebody has a chance to rest before the final critical part of the flight, which is the landing. >> would that mean that all four personnel are in the cockpit at the landing? or if one group is still -- how does that rotation work? >> that's not clear at this point. in fact, the ntsb chairman, deborah hersman, says that they're still not clear on that. i'm sure during the interviewers they're going to begin to answer some of those questions. there are many -- there are so many factor that could potentially impinge on this, that we don't no what they are yet. one way describing this whole