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Buoy Detects Another Possible Ping; Source: Flight 370 Captain Spoke Last Words to Ground Control

Aired April 10, 2014 - 17:00   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

WOLF BLITZER, HOST: Happening now, breaking news -- the mystery of Flight 370. A search aircraft detects what may be yet another signal from the missing jet's black boxes. The ping, which officials say seems made man, was picked up by a sonar buoy dropped in the search zone.

New clues to the airliner's disappearance. Sources now say that after Flight 370 made that sharp turn over Malaysia, it made a steep descent and disappeared from radar.

So was that intentional?

And investigators are now certain they know exactly who uttered those last words from the cockpit, "Good night, Malaysian, 3-7-0." And it isn't who they first thought.

I'm Wolf Blitzer.

You're in THE SITUATION ROOM.

ANNOUNCER: This is CNN breaking news.

BLITZER: We begin with new clues in the search for Flight 370, new details about its final moments.

Here are the latest developments.

A search plane has recorded a possible ping from the airliner's black boxes. The signal was detected by sonar buoys that had been dropped by the plane. Analysts are studying the acoustic data. Sources say Flight 370 disappeared from military radar after it made that sharp turn back over the Malay Peninsula. They say this means the plane must have dropped in altitude to between 4,000 and 5,000 feet.

And as aircraft prepare to go on another hunt for debris, the underwater monitoring continues in a search area that's now been dramatically narrowed.

Our analysts and our reporters, they're standing by here in the United States, as well as around the world, with the kind of special coverage that only CNN can deliver.

CNN's Michael Holmes is in Perth, Australia.

Let's go there first for the very latest -- Michael?

MICHAEL HOLMES, CNN CORRESPONDENT: Hi, Wolf.

Yes, a dozen of these sonar buoys, as they are known, have been spread around the search area, sort of an added tool, more electronic ears, if you like, listening for something, anything, from Malaysian Flight 370.

(BEGIN VIDEOTAPE)

HOLMES (voice-over): This time it was a search plane that picked up a possible signal from Flight 370's black boxes. It happened near the same area where the Ocean Shield detected four electronic pings since Saturday.

Aircraft have been peppering the search area with dozens of sonar buoys equipped with underwater microphones. And they heard something.

The search coordinator says the sound they picked up has the potential of being from a manmade source and is within the frequency range of a flight recorder. But more analysis is needed.

The air and sea search is intensifying, as search leaders grow more hopeful that they are closing in on the likely crash site.

UNIDENTIFIED MALE: We are, at this point, much more optimistic than we were even a day or so ago, and then certainly many more times optimistic than we were a week ago.

HOLMES: The hunt for Flight 370 now focused on the smallest area yet. It's about 2,200 square miles, or roughly the size of West Virginia. That's about 25 percent smaller than it was the day before. And it has narrowed dramatically from a few weeks ago.

As investigators pore over the latest clues, CNN is learning new details about Flight 370's final moments from Malaysian sources close to the investigation.

Investigators now believe it was, indeed, the plane's captain, Zaharie Ahmad Shah, who said the final words from the cockpit "Good night, Malaysian, 3-7-0."

We're told plc played the recording to five pilots who knew the captain and a copilot to confirm who spoke to air traffic controllers.

We're also getting a new explanation of what happened after the Boeing 777 turned west and crossed over the Malaysian Peninsula. Malaysian sources tell CNN the plane disappeared from military radar for about 120 nautical miles, indicating it might have dipped to an altitude between 4,000 and 5,000 feet.

(END VIDEO TAPE)

HOLMES: And, Wolf, a dozen planes and a dozen ships again will be scouring the ocean. The Ocean Shield, that vessel that's been towing the ping locator, has been joined now by a British Naval ship in the area where those pings were heard. It's called the HMS Echo. It's a ship that has the ability to scour the ocean floor, obviously trying to find signs of wreckage below. There are other ships, of course, a few hundred miles further west, where experts have been thinking any debris from the suspected crash site could have drifted over the weeks since the plane disappeared -- Wolf.

BLITZER: Still, they have not found any debris from that plane, have they, right?

HOLMES: That's absolutely right. They did find some suspicious objects that were spotted from the air. Ships went over, picked it up, but not related to the crash at all.

There were a number of storms in recent weeks over that area where the plane is thought to have gone down. And they've done all these sort of drift patterns and worked out the movement of the ocean. And that's why those ships are all concentrated about 300 or 400 miles to the west of where they're actually looking for the wreckage, because that's where they think any debris might have ended up -- Wolf.

BLITZER: Very intriguing, obviously, that they haven't found any debris at all.

Michael Holmes, thank you.

Let's bring in our aviation analyst, Miles O'Brien, our aviation analyst, the former NTSB managing director Peter Goelz, along with our law enforcement analyst, the former FBI assistant director, Tom Fuentes -- so this latest suspected ping, if you will, Miles, a fifth, if, in fact, it's serious.

What do you make of it?

MILES O'BRIEN, CNN AVIATION ANALYST: Well, it just adds to the case. We've had -- we have a strong case that continues to build. You know, I think the people heading up the search are reluctant to say we have the wreckage until they actually have eyes on it or virtual eyes on it.

But as they build this case, the evidence grows, and, more importantly, the box becomes a little bit smaller into which they decide to search and ultimately put on the Blue Fin device, the underwater vehicle that will go down and paint the surface with sonar. So it's very encouraging with, you know, the weather getting worse and winter coming, this is good news.

BLITZER: Peter, are you confident that they're getting closer and closer to at least one of those two black boxes?

PETER GOELZ, CNN AVIATION ANALYST: Well, I am. And the, you know, five pings is better than four. Ten would be better than five. I mean they've got to keep monitoring this area and hope that the battery is continuing to provide power so we can pick up the pings.

It's still a very large area, even though, as Miles said, it's much smaller, it's still awfully big.

BLITZER: What's your analysis -- Tom?

TOM FUENTES, CNN LAW ENFORCEMENT ANALYST: I would agree them, Wolf. You know, it is better that they've gotten more pings. And let's hope that it leads to locating the aircraft more quickly.

BLITZER: Peter, our Barbara Starr, our Pentagon correspondent, reported -- first to report the U.S., it was now sending a supply ship to the area to help the other searchers who are looking for some sort of debris from this plane.

What do you make of the fact that they're bringing a significant supply ship in?

It seems to suggest they're going to be there for a while.

GOELZ: Oh, I think they are. And I think they're getting ready for the long haul. If -- even if they do get four or five more pings, once they drop the side scanning sonar device down, boy, that is going to be painstaking and long.

So I think they're settling in for the long search.

BLITZER: Miles, what's your assessment?

O'BRIEN: Well, it just allows them to stay on site, Wolf. You know, given the distance to Perth to get some fuel and food and whatever you need to keep going, that could be a deal breaker for finding anything before the winter season.

So this is a crucial piece of equipment, if you will, that the U.S. Navy has supplied at just the right time. And I think it's the perfect way the U.S. Navy can contribute at this point.

BLITZER: Because they're going to need it. I've heard anything, Tom -- and let me get you into this conversation -- anything from days, weeks, maybe even months, even if they -- if these pings are the real thing, to actually go down there and find one or two of those black boxes.

FUENTES: That's right, Wolf. I hope they're bringing their long underwear, because they're going to be there all winter.

BLITZER: Do you think it could take that long?

FUENTES: It could easily, because you're also going to have the search and then, you know, transitioning, hopefully, if they locate it, into the salvage operation. So it's going to be a long haul out on the water.

BLITZER: Miles, that notion that the plane actually went down to 4,000 or 5,000 feet, the Malaysian airliner, as it was exiting or going over Malaysian air space, if you will, could that have been literally flying under radar? O'BRIEN: Well, it's a little confusing to me, Wolf, because the terrain in Malaysia offers up several peaks at about 7,000 feet above sea level. So if, in fact, he was flying at 4,000 feet above sea level, it's very likely he would have encountered what we call cumulus granite in the pilot business, which is a mountain.

So it would be -- it seems to me there's some confusion about whether this is an altitude above ground or an altitude above sea level. If it's above ground, it's 7,000 feet, plus 4,000, which puts us back at that 11,000 or 12,000, which we've already reported.

So I'm -- I'm just a little unclear as these numbers have been very confusing to me. And I'm told the Malaysian -- military radar -- is not very accurate.

BLITZER: What's your analysis of that, if, in fact, that plane went down to 4,000 or 5,000 feet, Peter?

What's your analysis?

GOELZ: Well, I'm skeptical of it. And I think that this is part of the problem that the Malaysians have had from early on in this investigation. They release kind of unsourced information and then it's corrected days later.

In this case, it seems awfully difficult for a 747 -- a 7 -- 777 -- to drop down from 35,000 feet to 4,000 feet and then regain altitude in what would be 130 miles. That's a real feat of airmanship, which I don't think occurred.

BLITZER: Do you think Malaysian Air Force crews on the ground, Tom, have that capability, if a plane, an airliner, a significant jumbo jet like this, is flying over their air space at 4,000 or 5,000 feet, they would miss it?

Is that possible?

FUENTES: Wolf, from day one, they've given us no reason to have confidence in the accuracy of their radar or their diligence in monitoring their own radar. And I think in this case, we're reporting this as fact when it's back channel source information that's not been released officially by the government. So I'm suspect or skeptical, like we all are, about the whole thing.

And then I'm also skeptical, then, because once you accept this, then you're saying, well, the plane did this. It went down. It was avoiding Indonesia. They're attributing all kinds of motives to the pilot when we don't even know if the front end is true in the first place.

BLITZER: All right, I'm going to have all of you stand by.

We've got a lot more to assess coming up this hour.

Up next, air crews are getting ready for a new round of search flights right now. But in a new twist, sonar buoys dropped by planes are bringing some dramatic underwater results. We'll speak with one of the search commanders. That's coming up live.

And investigators say they're now sure who was speaking in the last radio transmission from the cockpit.

So what took them so long to find out?

What impact will this have on the investigation?

(COMMERCIAL BREAK)

BLITZER: An extraordinary new twist in the hunt for Flight 370. A sonar buoy dropped by a search plane picks up what may be a signal from the airliner's black boxes.

Joining us now on the phone is Air Commodore Kevin McEvoy of the Royal New Zealand Air Force.

Air Commodore, thanks very much for joining us. Do you believe this was, in fact, the fifth suspected ping from one or two -- one of those two black boxes?

AIR COMMODORE KEVIN MCEVOY, ROYAL NEW ZEALAND AIR FORCE: Yes. Good evening, Wolf. The acoustic data still requires further analysis, but the understanding that we have from the chief coordinator of the joint agencies is that there is potential for the ping to be from a manmade source. So we've got our fingers crossed.

BLITZER: How much battery life do you suspect is still left in those -- those pingers from the two black boxes, the flight data recorder, the cockpit voice recorder?

MCEVOY: So the understanding that we have is that, while it has a 30-day nominal life, the battery life will still allow essentially a degraded signal strength. So we're anticipating that what we're receiving at the moment in terms of those pings from the coordination in the reports are that if they are manmade and they are coming from there, then there is still a very small signal strength. But every day that goes on, obviously, the signal reduces. So we're very keen to put the effort in to make sure that we -- the efforts that we're catching the signal that is there.

BLITZER: Are you dropping those sonar buoys into the water yourself as part of the New Zealand mission?

MCEVOY: The aircraft that are dropping the sonar buoys, those specific ones related to that specific piece of equipment, are only being dropped by the Royal Australian Air Force Orions at this stage, but in fact, we will have the capacity to do that. But at this stage it's, of course, only being utilized through the Australian Air Force.

BLITZER: So what is your responsibility, Air Commodore, right now? What is New Zealand doing?

MCEVOY: We've had a P-3 Orion in the search, potentially, since the 15th of March. It's day 35 of the search today. We'll be going out again today. We're airborne in about an hour, and we'll be going to the task area that we've got to search.

Every day our crews are out there doing a search. It's roughly the size of the width of Virginia. So in conjunction with the other airplanes. There's a total of nine sorties going out today. So they'll be very focused on the mission at hand and putting in another long, hard day to try and find some debris on the surface.

BLITZER: Just to be precise, so far, as far as you know, and you know what's going on, Air Commodore, you haven't found any, not even a tiny piece of debris from that Malaysian airliner. Is that right?

MCEVOY: We've found lots of debris but at this stage, none of the debris that we've found has been able to be linked to the missing Malaysian aircraft, unfortunately. So we'll continue that search today. The crews are motivated. The equipment is world class, and we're very, very focused.

BLITZER: Is there an explanation that you have and your experts have, why, assuming that these pings are, in fact, pings coming from one or two of the black boxes, is there an explanation why no wreckage at all on the surface or anyplace else has been found?

MCEVOY: I mean, the underwater search is not my area of expertise. But what I can tell you is that between the two search areas in terms of the debris and -- and the potential wreckage, it's likely that they will be in different areas.

So we'll go out. We'll play our crews and aircraft out in the debris area to focus on that surface search for the debris. But it's still a long, challenging search. The search authorities are doing everything that they can to gather all of their credible evidence to try and join those dots. So to date from all of the crews, all of the nations involved, and I'll be going out again today and continuing that good work.

BLITZER: How much longer are you prepared to continue this air search?

MCEVOY: Well, we are prepared to -- to support the search for as long as we require and as long as the national government tells us that that's their priority.

So I've got no intentions of bringing the airplane home at the moment. As I say, we're rotating crews through to be able to potentially support a sustained effort. So that's still a long way here, so to speak.

BLITZER: And you say the air search -- the air search is now, what you said, the size of about the state of West Virginia. Is that what you're saying?

MCEVOY: So every day the several area that they search is about the size of West Virginia. So it's -- it's a sizable search area, and that search area continues to either be refined, due to the ocean currents or the movement of that search, and the potential debris field. Or as you've alluded to, the more information that we get, we can refine and go to the various areas.

So there's a lot of -- a lot of search aircraft. There's nine search aircraft and three coordination aircraft up here today. A lot of ships in the area. We're very confident that, if something is on the surface, our airline will find it.

BLITZER: Air Commodore Kevin McEvoy of the Royal New Zealand Air Force, good luck to you. Good luck to all the men and women who are part of this massive, massive search. Thank you.

Coming up, investigators finally know who spoke the last words from Flight 370's cockpit. The voice of that transmission is not who they first assumed it was. And sources now also say the airliner made a dramatic descent and for a long time effectively disappeared from radar. We're going to tackle that mysterious development with our experts.

(COMMERCIAL BREAK)

BLITZER: We're getting some stunning new clues in the disappearance of Flight 370. Joining us now, our aviation correspondent, Rene Marsh, our justice reporter, Evan Perez, along with our law-enforcement analyst, the former FBI assistant director, Tom Fuentes.

The -- Rene, let's start with the new information that we're getting on the last person to speak those final words heard from the cockpit to ground control. Tell us about that.

RENE MARSH, CNN AVIATION CORRESPONDENT: Well, Wolf, we are now told by a source in Malaysia that it was actually the captain who spoke those last words, "Good night. Malaysia 3-7-0," as it was leaving Malaysia air space and going into Vietnamese air space.

Quite a difference from what we heard originally. Before we were told by Malaysian authorities it was the co-pilot who spoke those last words. So now this changes things quite a bit as to who was on the radio and who was communicating in the air with air traffic control.

We also know from this same source that it was five Malaysian Airlines pilots who were allowed to listen to the air traffic control radio transmissions to make the determination that it was the captain and not the co-pilot, as we had heard before, Wolf.

BLITZER: Tom, what's the significance if it was either the pilot or the co-pilot who actually uttered those final words?

TOM FUENTES, CNN LAW ENFORCEMENT ANALYST: Wolf, everyone I've talked to has says it's really not that significant regardless, that the captain is in charge of that ship, he would make the determination. His co-pilot or first officer is flying for the first time without another check pilot sitting behind him. So you know, if he decided to let him make the broadcast or take it himself, you know, we're not true that it has any significance.

BLITZER: What does it say to you, Tom, that it's taken the Malaysian authorities, apparently, so long to figure out who uttered those final words?

FUENTES: Well, that's a different story of how they've gone about the process, how many people they've had look at it. But you know, this might not be as easy as it sounds to identify the voice. You have two individuals in the cockpit speaking in their second language. Bahasa Melayu being their first language. And these are short, cryptic conversations. It's not a regular conversation with the tower. It's quick responses, short answers.

And as the plane moves further away, the radio may not be all that clear, and they may be on a speaker phone situation in the cockpit. So there's a lot of factors that would make it difficult to tell exactly who's talking.

BLITZER: Tell us, Evan, about the significance of the plane dipping. We've been reporting it went down to, what, 4,000, 5,000 feet at one point, maybe to try to evade radar. What do we know about this?

EVAN PEREZ, CNN JUSTICE CORRESPONDENT: Well, you know, Wolf, the investigators here in the U.S. are focused on trying to get as much information as they can about the people that are -- that are on the plane.

Obviously, the two pilots they are very much interested in. They're not sure, really, what to make of the change in the altitude. They don't know if it's definitive. It's certainly not going to be definitive until we can get the black box, until we can get some data or some information from the wreckage at the bottom of the Indian Ocean, and then they can go back to all the information that we already have and determine whether or not this tells us anything. But at this point, I think it doesn't need move the needle that much for the U.S. investigation.

BLITZER: What does it tell you, Tom, about this apparent drop to 4,000 or 5,000 feet in what may have been going on in the cockpit?

FUENTES: The problem I have with it, Wolf, is the whole concept that it made that drop. You know, what the authorities are saying is that we don't know exactly what it did, so let's assume it made a drop. We don't know exactly if it went around, that it didn't cross Indonesia air space. So let's say that it went around Indonesia.

You know, these are -- these theories are being based on information that we don't have, not on positive information that we do. So then that would mean that, if the theory isn't accurate, then the point of who is saying what, taking the plane up or down or sideways becomes invalid because we don't know for a fact that that's what happened.

BLITZER: We're also getting information, Rene, as you know that -- and this is, what, 35 days or so into this disappearance -- that Malaysian planes did scramble at some point after this plane went missing. Tell our viewers precisely what we're learning.

RENE MARSH, CNN AVIATION AND GOVERNMENT REGULATION CORRESPONDENT: That's right, Wolf. Well, again, according to a source there in Malaysia, these jets were scrambled as a precautionary measure on the morning of March 8th. Shortly after Flight 370 was reported missing. And again, this all happened or this action happened before data was corroborated that the plane actually made that westward turn.

That being said, we do know that Malaysian Transportation Ministry did send out a tweet denying this, but again, this is information coming from the source that this jet -- jet was scrambled over the Straits of Malacca in the short time after this flight was reported missing -- Wolf.

BLITZER: Thank you.

Evan, you've been talking to your law enforcement sources. What are they saying to you about their anxiety right now? Especially they are so determined to get at least one of those black boxes?

EVAN PEREZ, CNN JUSTICE CORRESPONDENT: Well, you know, Wolf, that is the key. And obviously the wreckage, to be able to examine that, you know, the FBI is going to be able to -- just standing by and waiting for the Malaysians to ask them to come and help. Once they have some wreckage, once the Australians are able to get some of this wreckage, to be able to examine stuff, and then they can actually have evidence teams go there and take a look at this.

You know, looking back at the passenger manifests and the -- and the crews and all that stuff, they are taking the time that they have right now to examine all of that. But none of that really will solve this. They are waiting for the black boxes, for the wreckage to be found to be able to put some light on what might have happened to Flight 370 -- Wolf.

BLITZER: All right. Guys, good reporting. Stand by.

Up next, the U.S. is sending a key new tool to the search team. Could it mean that they are getting closer to finding Flight 370?

Plus, the latest signal that's giving searchers new hope thanks to this device. We're going to give you a rare inside look at how all important technology is right now.

(COMMERCIAL BREAK)

BLITZER: First on CNN, a U.S. Navy supply ship is joining the international task force searching for Flight 370. It will be used to replenish off Australian ships participating in the search. Meantime, if and when key parts of the airliner are retrieved, American experts may step up their involvement in the investigation.

Our Pentagon correspondent Barbara Starr is joining us now. She's looking into this part of the story.

Barbara, tell our viewers what you're finding out.

BARBARA STARR, CNN PENTAGON CORRESPONDENT: Well, Wolf, the deployment of the Chavez Ship shows how long this may go on. They are going to need more help. The investigators have been on the sidelines for weeks while the search has been going on but now it looks like that all may be about to change.

(BEGIN VIDEOTAPE)

STARR (voice-over): As searchers potentially close in on finding Malaysia Airlines Flight 370, U.S. government intelligence, law enforcement, and aviation experts are quietly talking about what comes next. And at what point they'll take a bigger role in the investigation if new pings are found from the plane's black boxes. It could still take weeks to locate the voice recorder, which investigators hope will tell them what was happening in the cockpit. But it's the data recorder that may tell them the most about how the plane went down.

MARK WEISS, CNN AVIATION ANALYST: It's going to tell you what switches were moved, when they were moved, what your air speed was, what your altitudes were, you're your heading was. It's going to give you an entire picture of what that airplane was doing and when it was doing it.

STARR: If debris is salvaged, more clues for the U.S. to follow. If part of the frame is bent outwards, it could indicate an explosion. If investigators find a punched-in nose cone, an indication the plane hit the water nose first.

But still the question, what brought the plane down? And if it was a deliberate act, what was the motive? There has been no claim of terrorism found by the CIA, FBI computer experts found no evidence of wrongdoing on the pilot and first officer's computers.

Malaysian sources say the plane may have deliberately dropped to a low altitude, attempting to avoid radar. That low altitude could be one of the biggest indications Flight 370 was not having mechanical trouble and trying to avoid other aircraft for safety reasons.

WEISS: Did you hear anybody say that there was any emergency call? Why would you turn off the transponder?

(END VIDEOTAPE)

STARR: And so at the end of the day now, U.S. officials still theorize somebody steered that -- airplane away from land and they still need two answers. Who did it and why -- Wolf.

BLITZER: Barbara Starr at the Pentagon, thank you.

Let's bring back our aviation analyst, Miles O'Brien and Peter Goelz, the former managing director of the NTSB.

Those questions have been with us now for, what, 34, 35 days, Miles. The U.S. now sending the supply ship to help out. The search is obviously going to continue. They're not ready yet to give up hope by any means, are they? Especially now that they've had at least four, maybe five pings from what they suspect are those two black boxes. MILES O'BRIEN, CNN AVIATION ANALYST: Yes. I mean, I think if you had to, you know, put a number on the hope, the numbers are going up on hope right now as those pings come in. That not only provides more confidence in the right place but it also narrows the location of a potential search with that underwater autonomous vehicle that can use sonar to more or less paint the surface or the bottom of the ocean and give a picture of what might be there.

The wreckage will become very clear. It will take time to do it and that's why you want to get as many of those pings to sort of box off the location where you would ultimately put that unmanned vehicle in.

BLITZER: You used to do these investigations, Peter, at the NTSB. If you were involved in this one, is there anything you think at least as an outsider you would need that they're not getting right now?

PETER GOELZ, CNN AVIATION ANALYST: No. I think -- I think the investigative team and the search team has got every piece of equipment that they need. They've got everything that they've asked for. What they need is a little luck and they need those pingers to keep working for another week or so.

BLITZER: Miles, I suspect you want more, though. You would like everything they're doing right now but even more, right?

O'BRIEN: Well, as far as resources on the scene, you know, I think right now it's one of those situations where you don't want a lot of people near where that pinger is because you want it quiet in the ocean. And so it's kind of counterintuitive. At this point you want resources to back off, let them get as many pings as possible and then once you get, you know, an identified area of coming in and then it turns into a different kind of scenario where you've identified where the wreckage is, then you have to get another kind of vehicle on to the wreckage and then you have to get that vehicle to find these precise location of that cockpit voice recorder, that flight data recorder and retrieve them.

Those -- it's going to take a long time to get those to the surface given all of the steps that are involved there.

BLITZER: You think, Peter, this fifth ping that the Australians picked up is the real deal?

GOELZ: Well, I think we've got to go on the understanding that it likely is and let's hope that they find some more today and tomorrow. They need, as Miles said, to narrow this situation down. They are saying they're searching the area, the size of West Virginia. Let's get it narrowed down to the size of Lower Manhattan or something so that they can really start to put the resources into mapping the bottom of the ocean bed and finding the wreckage. But to do that, they've got to get a number of more pings.

BLITZER: Yes. The air search is the size of West Virginia, they're looking for debris approximately in the size of West Virginia. But, Miles, they say those four pings that were discovered, they -- that's in an area maybe two or three miles deep but it's an area of about 17 miles across. That's a lot smaller than West Virginia. That is about the size of Lower Manhattan.

O'BRIEN: Yes. We've got to clarify that point. There's two areas obviously. There's the area where they're honing down on those pings. That's a smaller area. And there is the larger area where the search for debris continues. And that is still complete mystery to those of us who have any experience with covering these sorts of things, who are actively engaged in these investigations.

The fact that they haven't found any debris is just extraordinary. Now they -- they're using ocean currents and predictions about where the debris might have drifted from the location where these pings are located and that's what gives them this area the size of West Virginia. Hopefully they will find something floating there.

BLITZER: All right. Guys, stand by. There's a lot more coming up. Just ahead, a possible black box ping detected by a sonar buoy which was dropped by an aircraft. We're taking a closer look at the latest high-tech clue in the search for Flight 370.

(COMMERCIAL BREAK)

BLITZER: As the underwater sweep continues, another possible signal from Flight 370's black boxes has been picked up from a sonar buoy dropped from an aircraft. Analysts are going over the acoustic data right now.

Our Brian Todd has been looking into these high-tech devices.

Brian, tell our viewers what you're discovering.

BRIAN TODD, CNN CORRESPONDENT: Well, Wolf, search teams are stretching the balance of technology in this operation and they've done it again. The latest detection of an underwater signal came from sensors that were designed for maritime combat, not search and recovery.

(BEGIN VIDEOTAPE)

TODD (voice-over): They are dropped out of a plane, plummet into the sea with a parachute. Descend below the surface, open up their payload and hunt for their target. These aren't bombs or torpedoes, they're called sonobuoys.

COMMODORE PETER LEAVY, ROYAL AUSTRALIAN NAVY: Sonobuoys are essentially a sense of package that's parachuted out of the aircraft. Floats on the surface of the ocean and will deploy a hydrophone.

TODD: An Australian defense source tells CNN it was sonobuoys that detected the latest possibly man-made signal in the search area. They were dropped from an Australian P-3C Orion plane. VAN GURLEY, FORMER NAVAL OCEANOGRAPHER: And once it hits the water surface then it's got some saltwater switches that starts activating different deployments. Everything that in this canister starts to unwind. There's a bunch of gear in there. Just packed in very nicely. Some of it floats to the surface so there's a radio antenna that talks to the aircraft, so the buoy in the aircraft are constantly in communication, and then the microphone, the hydrophone that actually listen for the signals went a very long strain and they deployed below the canister.

TODD: The Australians got this batch from American manufacturers, sent a cargo plane to Indiana in recent days to pick up more than 1,000 sonobuoys. The device was first tested and deployed by the U.S. Navy but not for this purpose.

GURLEY: In an anti-submarine work this is one of the tools the Navy has to look for and track enemy submarines so they're under the ocean surface, they don't have a radar signature and you need to use sound in smart ways both actively and passively to find them and then track them.

TODD: On this mission the sonobuoys and the Orion planes deploying them have been modified to detect sounds in the frequency range of black box pings. Sonar operators on board the aircraft are manning computers to receive and analyze the signals.

Sonobuoys are dropped in a pattern, 84 of them at a time. They have a shorter range to detect signals than the towed pinger locator, but they're durable.

GURLEY: The beauty of these things, the sonobuoys, once you put them out they stay out there for a long time, up to eight hours.

TODD: Then they expire and sink to the bottom.

(END VIDEOTAPE)

TODD: But while they're deployed the sonobuoy can go about 1,000 feet down. So how could they detect signals possibly from a black box which could be as far down as 14,700-plus feet? Well, experts say the sound moves through the water in a manner that it could be detected further away and with good weather, signals are a lot easier to hear -- Wolf.

BLITZER: Interesting stuff. Is there any chance these sonobuoys could possibly go deeper than 1,000 feet?

TODD: Possibly, Wolf. Our source in the Australian Defense Force is confident that the technology has been tested at a much greater depth during this entire operation. So you can surmise that they are going to try to get it down further. They want it -- you know, they want to be able to cover as much -- as much water underwater, as much of this area as possible. And they need to max out the use of these sonobuoys.

BLITZER: Yes. Time quickly running out as well for those batteries on those two black boxes. Thanks very much.

Coming up, crews are racing against the clock to catch those final pings. Will they reach the wreckage before the black box batteries run out?

And the president as we rarely see him. His emotional address on race, the civil rights act, and President Lyndon Johnson.

(COMMERCIAL BREAK)

BLITZER: We have much more on the search for Flight 370 coming up. But first, some other urgent stories we're following.

Police are searching for answers one day after a 16-year-old suspect went on a rampage at a Pennsylvania high school. Alex Hribal is facing four counts of attempted homicide, 21 counts of aggravated assault after the mass stabbing in a quiet Pittsburgh suburb. Police have seized the suspect's computer and cell phone but no word yet on a motive.

Obamacare numbers are climbing even higher. 7.5 million Americans are now enrolled in the federal or state exchanges. That's up 400,000 since April 1st when the administration announced that it passed its target of seven million. The numbers are a surprising victory for the president after the federal Web site's disastrous rollout made for a slow start.

The House Oversight Committee is charging a former IRS official with contempt of Congress. Lois Lerner has refused to answer questions for the Republican controlled committee by pleading the Fifth. She's accused of blocking conservative groups from tax exempt status for political reasons. Democratic members argue the investigation is a witch hunt and a political stunt. The contempt vote now moves to the House floor.

President Obama is in Austin, Texas, today celebrating the legacy of President Lyndon Johnson and marking the 50th anniversary of the Civil Rights Act. In his speech, the president got emotional. Praising the longtime Texas senator for using his political capital to pass major laws and becoming an unlikely hero in the civil rights movement.

(BEGIN VIDEO CLIP)

BARACK OBAMA, PRESIDENT OF THE UNITED STATES: The ability to connect his experience with the brown child in a small Texas town. The white child in Appalachia. The white child in Wise. As powerful as he became, in that Oval Office, he understood them. He understood what it meant to be on the outside.

And he believed that their plight was his plight, too. That his freedom ultimately was wrapped up in theirs. And that making their lives better was what the hell the presidency was for.

(END VIDEO CLIP) BLITZER: The president also noted that the landmark civil rights legislation helped pave the way for him as the first African-American president.

Coming up, special coverage of the mystery of Flight 370. Air crews are preparing for takeoff after another possible ping from 370's black box. Could this be the day?

The SITUATION ROOM continues in 60 seconds.