Violent storms are threatening the countrys midsection and much of the south. Im wolf blitzer. Youre in the situation room. There are no details on the hunt for flight 370 50 days after it disappeared. The u. S. Navys underwater drone is scanning the last 5 of it is targeted area. It it cant find a trace of the airliner, authorities plan to expand the search zone and may bring in different technology. And angry flight 370 families making a rare show of civil disobedience in tightly controlled beijing. Theyve marched through the city and staged a sitin at the embassy. Our correspondents are standing by around the world. Bringing you the kind of coverage only cnn can deliver on the search for flight 370. The worsening ukraine crisis. And a threat of violent storms and tornadoes across much of the countrys heartland. Lets begin with cnns Miguel Marquez. Hes got the latest in perth, australia. Miguel . Hello there, wolf. Clearly things are in transition both the hms echo and the hms tireless that had been participated in this search is now headed to port or is now in port. The ocean shield is continuing to search for that plane but says its now searching areas adjacent to that most hoped for area to find flight 370. Reporter a new show of anger by flight 370 families camped out in beijing chanting tell the truth and stop lying. Several thousand miles away, a source of their frustration, the bluefin21, the most promising, returns two weeks later with nothing to show for it so far. If no leads turn up once the whole area is covered, coordinators now confirm that the underwater drone will scour stretches of the nearby ocean. The bluefin has been combing deep waters, about six miles around the second ping that was detected, a possible signal from the jets black boxes. No official word yet on what technology will be used next but we learned that the british navys world submarine is out of the mix. Its no longer needed to hunt for pings now that the black box batteries are believed to be dead. Australian and malaysian authorities are holding urgent talks about the next phase of the operation. This is totally unprecedented. What do we have going for us . What is the evidence . The evidence simply lie with the pings. The handshakes that we have analyzed. Thats all we have. Reporter the malaysian Prime Minister in an exclusive interview claimed that investigators have not had much to go on. Hes promising to release a preliminary report on flight 370 investigation next week exactly seven weeks after the plane vanished. Many of the relatives of those that were on board are very skeptical. Actions speak louder than words. The briefings have been a joke. Now, what is not clear, wolf, is whether or not they have any more math to go to, basically, the way that they picked up the pings and how they map where they are searching right now, where will they go next . Will they just continue to search around the edges, go to the area of the first ping or reset the entire operation for a much broader search. Wolf . Miguel marquez, from perth with the latest. Lets get now to the fallout with cnnthe malaysia and the pr minister spoke about said putting the best foot forward and many say why didnt you put this into the National Arena sooner . I think on the familys question, wolf, theres still quite a lot of people who dont quite understand how this relationship has deteriorated so badly, so quickly. And those are those who simply say the families will never be satisfied and those who say actually what the families are asking for is legitimate and malaysia needs to step up to the plate. The preliminary report that was provided to the international u. N. Body, that that report would be made public. Are you getting any indication when it will be made public, what day . Reporter no, i havent. And ive asked several times and obviously ive asked before then. And it will be impossible. Note the word. Impossible for the malaysians not to release that report next week. Even if the committee looking at it decides the entire report needs to be redacted except for one word, preliminary and report underneath it. They are going to have to release something next week. And then, wolf, it becomes an issue of how the Prime Minister intends to enforce this transparency on perhaps other areas of government that dont see it in quite the same way. So the cargo manifest, the new passenger list, the maps, any other documents that they may have that would be of use to understanding. You cannot have a pm saying that hes following a policy of transparency and then documents saying we cant let you have this. Well stand by for that next week. Richard, dont go away. I want to bring in our aviation analyst peter goelz and tom fuentes and ken christensen. So they are 50 days in now. Peter, they havent even found an iota of the wreckage. 95 done and 5 left to go. Presumably they wont find anything. Where do they go from here . Well, theyve got to keep searching. Its terribly disappointing. I dont think it was unforeseen but its terribly disappointing. They should have set expectations lower. But theyve got to keep searching and keep searching for one of the pings and search around those. They made a big deal about those. Lets check them out. The Aerial Search, ken, is that over for all practical purposes, they havent seen anything significant, anything at all, is it over for all practical purposes . I would say at this point, wolf, the Aerial Search is over. Any debris that would be from that wreckage would be thousands of miles away at this point. Tom fuentes, if you were in charge of this investigation, what would you do now . Well, i think they are going to have to do what theyve talked about, the regroping of how they are going to expand the search, what kind of equipment they are going to use for it. I find it interesting that the Prime Minister, when he mentions all that they have to go on, is the inmarsat satellite data, which is britishcontrolled data and machines operated off an australian ship, he omitted any mention of malaysians defense radar or their aviation radar and i think that thats a critical part of it, especially as richard mentions when they announce that theyve released this preliminary report to the International CivilAviation Organization but not to the families, not to the public and they are waiting a week creating a greater mystery, creating greater expectations for what im sure the report is going to have next to nothing useful in it. Lets ask Richard Quest to react to it. You spent quality time with the Prime Minister yesterday. What do you say about what tom just said . Reporter i think ive seen and ive spoken to people about the radar data. The radar data is so basic and if you look at the picture, its basically blips with a gap in the middle of it after it follows after it crosses across malaysia and into the straits of malaca. So the extent of this, tom is right. It does take the plane into the straits of malacca and then onwards. But there after, and this will be the difficult part, wolf, if they do have to discount inmarsat material, then you really do go back and the pm said this, you go back to 222, the last known data from the military radar and if youre back at that level, well then i think we are really turning the lights off and going home because youve got no idea where the plane goes after that. Peter, heres a blunt question. They were some confident early on, several moments when they got those pings, the four pings from what they thought were the black boxes. It all looked pretty good that they had honed down a huge area to a relatively tiny little area but found nothing. Is it possible that they are looking at the wrong place to begin with right now . Boy, thats hard to believe. I mean, they did a most complex mathematical analysis from the pings, from the handshakes, they believe they had the spot. They believed they had the spot. Its going to be tough. They are going to keep searching there but, boy, i think they were a little enthusiastic when they first announced the pings were heard. Let me quickly go back to Richard Quest in kuala lumpur. In the interview you did with the Prime Minister, he acknowledged that there were shortcomings, that mistakes were made. Did he seem to you confident that this is going to be resolved any time soon . No. Absolutely not. I think that anybody i mean, peter will know this from his own investigations over the years. Tom will know this. Anyone of us who have touched this and looked at these sorts of incidents will be well aware that the investigators are in this for the long haul. They hope for the best. They believe in maybe the worst and they know that this is the hard dredgry and anyone is otherwise a fool. Quick question for you, tom fuentes. He dropped the cell phone into some water, Similar Properties in the indian ocean and, guess what, videos, photos, once the phone was retrieved, they could go into that cell phone and get a lot of that information. So presumably a lot of those people on that plane, 239 people that had cell phones, if they ever retrieved some of those phones, they would be able to collect useful information. Dont you agree . I would i a agree. I saw that piece conducted in my home town of chicago and i thought it was amazing that they were able to pull that mother board or the ship out of the immersed cell phone and what will happen if they dont find this plane for two years like the air france plane, how much more damage will salt do to the phones that are hopefully retrieved if they are on the bodies. Ken, does it shock you that 50 days into this investigation they have not found even a tiny little piece of that plane . At first it surprised me that there was no wreckage but that probably says that they were looking in the wrong area and the currents there in that part of the world in the indian ocean are just so unpredictable, the debris field can disperse pretty rapidly. For a wide body airplane hitting the water, you would think that there would be more wreckage than what they found. Im confident that the pings that are coming from the underwater locator beacon, they have not expanded the area and they will probably find some wreckage. Lets see if they do. Hold on. Were going to continue our analysis. But up next, distressed beacons stayed silent when night 370 went down. Heres the question. Why . And Russian Troops holding military exercises on the border with ukraine. Ukraines leader now saying that moscow wants to start world war iii. Well have the latest on the escalating tensions. Are you ready grandma . Just a second, sweetie. [ female announcer ] we eased your back pain, you turned up the fun. Tylenol® provides strong pain relief while being gentle on your stomach. But for everything we do, we know you do so much more. Tylenol®. There was a boy who traveled to a faraway place we know you do so much more. Where castles were houses and valiant knights stood watch for the kingdom was vast and monsters lurked in the deep and the good queen showed the boy it could all be real avo all of great britain, all in one place book on expedia before april 30th and save up to thirty percent. A short word thats a tall order. Up your game. Up the ante. And if you stumble, you get back up. Up isnt easy, and we ought to know. Were in the business of up. Everyday delta flies a quarter of Million People while investing billions improving everything from booking to baggage claim. Were raising the bar on flying and tomorrow we will up it yet again. Theres another type of locator signal that is supposed to be activated in most crashes. This time, though, it stayed silent. Brian todd has been looking into this part of the story for us. What are you finding out . Wolf, there are four of these devices called emergency locator transmitters on board the missing many. They are supposed to send locators out on impact. Not one burst was sent from flight 370. Could the possible reasons why these didnt work lead us closer to finding out what happened . Its one of the most baffling questions in an already con founding mystery. Why didnt any emergency beacons send a distressed signal . They are called elts. And a senior aviation source tells cnn there were four of them on the plane. Emergency locator transmitter is a small radio transmitter that sends a signal detected by satellites in the event of an airplane crash. Reporter signals sent to satellites relay to satellites on the ground. The signal coming from the black boxes containing the flight recorders. These beacons are designed to be activated if they sense extreme deceleration or by impact. Those circumstances could have played out with flight 370 but experts say there are other possible scenarios with the missing plane where the elts would not have worked. If it crashes with too much velocity so the plane is dissin rated. Also, like the hudson miracle, if it went down softly. Reporter also, theres a time lag after impact. It takes 50 seconds for the first signal to be transmitted. Even after it hits the water, it has to stay afloat for more than 50 seconds or they wont do either. Reporter triggered by contact with salt water might be useless because elts dont work under water. Once these things become submerged, the radio signal is no longer able to reach the satellite. Could the emergency locator transmitters attached to the fuselage probably would have been inaccessible to anyone on board. It could have been tampered with, wolf. This whole issue with four signals that were supposed to come from the transmitters and none of them worked, its really become a source of a major concern for the families of those on board. It sure has. Recently the families submitted a list of 26 questions to malaysian officials about a whole range of things regarding the investigation. 12 of those questions delved into that issue. Brian, thanks very much. Lets discuss what we heard from brian. Once again joining us, cnn aviation analyst, peter goelz and chris van alt. Those families, peters, they see this, the fact that these transmitters didnt work, all four of them didnt work for whatever reason has potential evidence that the plane may have actually landed on land someplace and their loved ones are still alive. Thats exactly right. They think against all reasonableness of, you know, that these are the facts. Maybe, just maybe the plane landed. And if thats the case, any kind of explanation says the antenna might have broken off or might have dropped too quickly. Weve got to find the wreckage. Let me bring in chris van alt into this. You helped develop the technology that was successful in finding air france h447, the remus. Well, its always best to get the best equipment on the scene as quickly as you can. But i would defer to the people who were on site. They know what is going on there. Certainly the systems that we have in there, their proven capabilities during the flight 447 search would substantiate that they would be a great asset in this location. Explain why the remus is so successful in the air france disaster. Well, many of the people have talked about this like trying to find a needle in a haystack and i think a better analogy would be trying to find a dime in a football field at night. And all you had to look for with for this dime is a small penhike. You find yourself crawling around in the dark at night and learn very quickly the biggest problem you have is navigation. You want to make sure that you covered every aspect of the ground and you know that you are there. We owe that to the victims of this tragedy. So its the navigation that you worry about. Making sure that you have 100 coverage. Our vehicles are very good at doing that and they can do it very quickly. Peter, is it time to bring more submersibles too this search . Theres no question. Its time to bring in submersibles that are towed, that have contact with the surface, that can do a broader range of search. Because were now getting into were going to have to search a lot of that ocean bottom. Much more significant area. Chris van alt, what about the whole notion of wear and tear on those individuals involved in the search . Its now been 50 days. Are you worried about fatigue . Are you worried that its simply getting too much and they should simply take a break and rest up . No. I think most missions of this nature take about 37 days. So i think the time that theyve been out there is reasonable. They will come in when they have to. They do well. You know, i spent 30 years developing technologies in the deep sea and spend the first ten years of those 30 developing deeply towed systems and i learned the capabilities of the towed systems and those limitations led me to write a proposal to develop remus 6000 because we could do much better with it. I think we need to use the technology that is best. You dont want to use Old Technology to solve new problems. Chris, peter goelz, thanks to you as well. Well have much more coming up. Also coming up, were getting breaking news of an american man now detained in north korea. We have more information coming into the situation room. And president obama says sanctions against russia are ready to go. But what will it take for him to pull the trigger . Stay with us. Youre in the situation and the breaking news coming into the situation room right now, new information about an american, an american being detained in north korea. Lets get right to our chief National Security correspondent jim sciutto. What are you learning . Wolf, this appears to be a very strange case, extremely unusual. The 24yearold american was with a tour group to north korea and as members of that group describe it, he appeared to go to the North Koreans willingly, including tearing up his visa as he did his behavior described as strange. The u. S. First learned of this case days ago, though not from the north korean government. The information has been limited to that the u. S. Is aware of the reports and is in touch with sweden which handles u. S. Problems in korea. Its a very bizarre situation since presumably the u. S. Has known about this for days, were only learning about it right now. Thats true. Typically in these cases they dont want to inflame the situation. They want to keep it private for as long as possible and also to find out what the circumstances are of how he went over to the North Koreans and its very strange. We dont know if he volume lun tearivolume lun tearily wen across or if he was physically abducted or detained or anything like that . Well, right now it appears that he doesnt appear to have been taken or abducted. It was a decision to go, based on what witnesses how witnesses described it. Witnesses from the tour group he was on .