they've been asked to help finding the black box. what does this mean other than the obvious? that the malaysians believe the best chance the plane hit the water in that area? ? the process of elimination, there's discussion the plane, especially if altitude numbers are right -- we don't think they're completely accurate. they were flying low up and down. they didn't have the fuel to go over the him lay yans and take the northern route. >> they say we were tracking a flight, think it was 370 because of the direction it was going and wasn't transmitting data. how helpful is this in limiting the search area? >> very helpful. radar has a definition, a range, that you can clearly see things. this was primary return. that's well known how far the signal will travel. that's going to be very limiting