a limited number of tooling you can use at that depth for this purpose. bluefin has a relatively small range, but has good resolution. so if they re in the right place, they will find it with this tool. so you re still feeling fairly confident that the pings that they heard were that of pings that would be associated with black boxes? not necessarily false positives? i m not confident in that at all. you know, i knew the people on-site, that they re equipped with the information to make those decisions. only those people. there are only a certain number of things that those pinger sounds can be, and if they are from mh-370 and they re in the right place, then the bluefin will find the target. if it s not, of course, it means complete redrawing of the search area. and so, you know, thomas, do you believe searchers are at that juncture where it s time to redraw the search area?
from the surface. the water is three miles deep. the range of these things is two and a half miles maximum. so only if it is directly over the pinger and the pinger is operating at full strength are you going to even have a chance of locating something on the sea bed. so doesn t seem to be a break. listen, as this has been going on you know we ve heard about how they re narrowing and narrowing the search, in fact they re not narrowing it. if you look at where the pinger sounds have been found, the area gets bigger and bigger, it is not converging. it is diverging. this is not what a situation should look like, if it is real it should be operating at the right frequency, which it is not. if the paths diverge, we re getting stuff that is further and further apart. it is very confusing. it is not very encouraging.
weaker. that s correct. and some of the other characteristics may change as well. meaning? longer pulses in. depending on the design of the unit. it may retain the characteristics and get weaker or perhaps the signal will start getting slower and slower as well as weaker. it depends on the manufacturer. stick around. our panel of experts will be here a little longer. last hour we played some of the pinger sounds. we ll hear those again and discuss next.
flight 370. but time is running out for the pinger s battery life. what they re trying to do is get ears in the water while the pinger is still going. reporter: this is the sound it s listening for. the towed pinger locater, or tpl, is 30 inches long and weighs just 70 pounds. it s towed behind the ship that operates it, in this case the ocean shield, and generally moves at about 3 knots. that means with 150 miles or so to cover, just a sliver of the search area, it will take days. it does two things. it gets it down into that level. it also gets it away from a lot of the surface not. wind on the water creates noise, propellers, dolphins, animals, fish, they all make sounds. reporter: the device can pick up the pinger sounds in depths ranging from 50,000 feet from two miles away. here s why it s so critical to
fish, they all make sounds. reporter: the device can pick up the pinger sounds in depthing ranging from 50,000 feet from two miles away. here s why it s so critical to get that towed pinger locater down in the deep ocean. the block box can get stuck is in something called a deep sound channel. if the sound does get trapped there and bounces around, the only way to pick it up may be through one of these pinger locater devices. sending the towed pinger down there, the tpl, will put you in that channel so they can hear that echoer or ricochetting sound. when it picks up the sound it s in real time sent up the cable of the boats. in real time the scientists and technicians on board the boat will be listening. reporter: pinger locaters have been used for years. in 1996, a tpl successfully located the black box for twa flight 800, though that was in