to do this. >> reporter: officials at phoenix international, the manufacturers of the pinger locater agree that these conditions are far from ideal. to be most effective, it needs a starting point, a confirmed piece of wreckage from malaysian airlines flight 370. if they haven't found debris, is it pointless to use this? >> your question pointless is not a good description. it is very, very difficult if they have not found debris to even know where to start. >> reporter: the pinger locater notifications it listens to signals from the pinger ask does not send signals to pick them up. underwater hills or mountains can impede it. >> weather is a big factor. if the boat is doing this on the ocean waves, now you're attacked to this thing and this thing goes up and down and much less stable in the water. >> reporter: the first towed pinger locater was designed in 1976 in the last 18 years, it's