a cell phone signal, it was picked up from the co-pilot's cell phone after the plane made that suspicious west turn. cnn seasty analyst david suoucy say that should never happen. >> rare in my opinion to have someone with a cell phone on in the cockpit, never supposed to be on at all, part of every economic list i'm familiar w >> not supposed to be on. it is interesting to hear david say that certain protocols pilots are supposed to follow, especially in the precheck and once they are in the air. right. >> what is your take away about this cell phone being detected on the co-pilot's cell phone? >> i think given that they do have this very specific checklist, that is part of the checklist, i find it very suspicious that the cell phone signal was picked up. it was picked up in an area that, you can see the cell phone tower sort of near the coast, it