moves at about three knots. that means with about three miles to cover 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 noise, all of the whales, dolphins, fish, they all make sounds. the device can pick up a sound from as far as two miles away. here is why it is so critical to get that towed pinger locater deep down in the ocean. the pinger sound from the black box can get stuck in something called a deep sound channel. about 2,000 to 4,000 feet below the surface. if the sound does get trapped there and bounces around the only way to pick it up may be through one of these towed pinger locaters. seeing the device down there, that will put you in that channel so they can hear the
using, detected those pings within the first two days. was that just a stroke of luck? it could have been luck. i mean, this story is every it s written like it was written because every time something looks like it s over, something miraculous happens and they find a satellite picture or in this case the ping. very likely it could be the last ping, but as you noticed the geology is extremely rugged there, so sound can bounce off of things and you could get a pocket of sound where you get outside of that you don t have it, so it s not just a flat plain. it s very difficult. you wouldn t say yet that if we had if those were, in fact, pings from the black box and we haven t heard them again, you wouldn t say that means that the battery is definitely gone dead? i wouldn t say that. there s another thing. in deep water, there s a deep sound channel. that sound because of pressure and because of depth and because of at the particular time, sound can get in it, and that s a goo
minutes, it s quite possible that they did get a piece of sound coming through what s called the deep sound channel. about 2,000 to 4,000 feet deep. essentially, sound can come up and be caught in that channel. they could have picked up a minute and a half of the signal and lost it. the towed pinger. that s why they re going deep. the submarine is in there because i think they can get into unclassified depths are 2,400 feet for these submarines. i believe they re getting into the deep sound channel. one quick question for richard quest. i hate to do this, but it s critical. early on in this mystery everyone asked the question about about the elts? they re supposed to be activated by salt water. we haven t talked about that in about 31 days. i m still not sure i understand why none of them onboard, and there are several, were activated. if this thing s in water. and no one can give you the answer. oh, there ll be plenty of
perspective when we re talking about teeny tiny microphones looking for teeny tiny black boxes. they create walls. sound can baounce off it and no make it through it. put a sub right above or below one of those, and they re shooting sound to find a sub they can bounce off the therm aa thermales and not see the sub. if the toe pinger locater is being towed behind the vessels in question, they have to be exactly in the right thermal layer in order to detect something? more or less. there s one layer that travels the whole ocean from 2,000 to 4,000 feet. it goes up and down. it s a deep sound channel that sound can get caught in. propagate for miles. the sound can get caught in there and not make it through. parts of it can make it through. that s why that pinger is being deployed. they re towing that pinger down into about 3,000 feet of water where they can actually get into that zone and maybe even pick up
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