to inform the search as it proceeds. and the primary bit of evidence that everybody is working off of at the moment is the data from the satellite. those handshakes. that's what led us down to that part of the world and what will keep us here for the time being. >> david, is it possible that these pings that authorities were such a strong sign of the plane, there were four different rounds of pings, is it possible they just got it wrong? >> no. not in my eyes. what they did is they went after the ping that's in the center of all of the pings. so that's one approach and you could do it that way and the reason they picked that location is because the equipment that they had aboard the ship could look in that area. so i don't think it was the most promising area for finding the aircraft although it was broadcast that way and appeared to be that way. i think the most promising area is where they had a long period of pings, which is the number one ping for two hours they got it there. remember, that's a much deeper part of the ocean, a much more