hi there. i'm brianna keilar in for wolf blitzer. you're looking at video moments ago of president obama arriving in austin, texas, about to speak at the lbj library marking the 50th anniversary of the civil rights act. as soon as it gets started we'll be taking you there live. we will talk about another dramatic story, the mystery airline flight 370.

search crews or look going for the signal of the black boxes. sources tell cnn, the plane disappeared from radar about 120 nautical miles after crossing through malaysia meaning it must have dipped as much as 4 or 5,000 feet. malaysia's airlines scrambled signals but didn't tell military officials until three or four days later and the pilot was the last to speak to traffic controls with good night malaysia 37 zero. nic robertson joining us from kuala lumpur. walk us through what you're hearing from sources how long the plane was out of radar contact and what exactly this

means. >> reporter: this is the first time we've been told of an altitude variation of the aircraft. the many ply indications are that the aircraft was taken down an altitude under control and taken back up under control. what we're told remember the aircraft took the left turn off the original flight to beijing and flies back over the malaysian peninsula, back over the malacca straits and then lost from military radar after dipping down and reappears on military radar 120 nautical miles northwest of that position. we're being told because it disappeared from military radar, the belief is it dipped down below 4,000 or 5,000 feet. the reason investigators believe it did this because it was flying across busy civil aviation routes from asia to

europe to india. that's one of the reasons it dipped down. it ad adds to the complexity ofe investigation. >> we will be getting back to our investigation of flight 370 in a few minutes. first, we're going to austin we told you we are following, the 50th anniversary of the civil rights act at lbj library. this is mabel singing. ♪ we walk hand-in-hand we'll walk hand-in-hand ♪ ♪ some day hey deep in my heart you know i do believe that we'll

walk hand-in-hand some day ♪ ♪ mm-hmm we shall live in peace one day we shall live in peace ♪ ♪ we shall live in peace some day yeah ♪ ♪ deep deep in my heart you know i do believe that we shall live in peace some day oh yes god is

on our side ♪ ♪ god is on our side god is on our side oh today yes he is ♪ ♪ yes deep deeply in my heart you snknow i i do believe that d is on our side some day ♪ ♪ everybody hey we shall overcome sing it ♪ ♪ we shall overcome oh yeah we shall overcome some day ♪

♪ deep in my heart you know i do believe that we shall overcome some day ♪ one more time, come on! [ applause ] yeah! we shall overcome! some day, y'all, some day!

>> all right. that was a beautiful performance by mavis staples that we just watched there. this is austin, texas, at the lyndon biananes johnson presidential library honoring the civil rights anniversary that made it illegal at buses and restaurants and schools. this is a big occasion. we will be seeing a number of speakers.

president obama will be talking in just a moment for this occasion, but we're also going to be hearing from the director from the lbj library, mark up uptogrove and here he is. >> welcome to the civil rights summit as we welcome the president and first lady of the united states. we shall overcome. that song became an anthem for the civil rights movement. for those who fought against racial injustice, those words have special meaning. on march 7th, 1965, john lewis helped to lead a protest march for voting rights from selma, alabama, to the state's capitol, montgomery. the march was brutally thwarted by alabama state troopers in a day of infamy that became known as bloody sunday. president lyndon johnson was

never one to let a good crisis go to waste. a week later, he used bloody sunday to show the need to pass the voting rights act that he had proposed but that had stalled in the halls of congress. in a plea before congress and the nation, he said it is all of us who must overcome the crippling legacy of bigotry and injustice. and we shall overcome. john lewis watched that speech in selma, with his mentor, dr. martin luther king at his side. as president johnson said those words, mr. lewis saw dr. skinni king cry for this first time. we will march from selma to montgomery, dr. king said with tears in his eyes. the voting rights act will pass. dr. king and mr. lewis made their march from selma to

montgomery and president johnson passed the voting rights act. if we have overcome the crippling legacy of bigotry and injustice it is largely because of courage and fortitude of those like lyndon johnson, martin luther king and john lewis. ladies and gentlemen, please join me in welcoming to this stage, congressman john lewis. [ applause ] >> thank you, mark, and the

staff of the lyndon johnson library. my beloved friends, my sisters and brothers, i have the special honor to introduce the keynote speaker of this celebration of the civil rights act of 1964. it is so fit iting and so appropriate that president barack obama would join us today to honor the legacy of president lyndon johnson. now, president barack obama was born into a dangerous and difficult time in american history. a time when people were arrested and taken to jail just for sitting beside each other on the bus. it was against the law for

black-and-white people to ride in the same taxicab or stay in this same hotel. people's homes were bombed and life taken for taking the same drink at a water fountain or sitting at the same lunch counter. there were signs everywhere that said white and colored and they impose an unholy order on the lives of the average american citizen. president johnson used his political power and the force of his will to pass the civil right act in 1964 and later the voting rights of 1965, all of those signs came tumbling down. you will not see those signs. our children will not see those signs, except in a museum, in a back or on a video.

president lyndon johnson, this man from texas liberated not just a people but an entire nation from inhumanity, and illegalized segregation. [ applause ] without the leadership of president lyndon johnson involving hundreds of thousands of people in the civil rights movement, there would be no president jimmy carter, no preside president bill clinton, no president barack obama, lyndon johnson, using his skill and his power made this possible. when people say nothing has changed, i say come and walk in my shoes and i will show you change.

[ applause ] . when president barack obama walked through the doors of the white house he ushered in a time of great hope. silent prayers and deep aspiration. as a nation, we felt we may have finally realized the vision president johnson had for all of us, to live the idea of freedom. eliminate injustice from our beloved country. we used the liberty we gained from johnson's legacy to elect a man with the raw courage and tenacity to do all he could to make our society a better place. and move us closer to the beloved community.

i know this man, this president, barack obama. you see the progress we made as a nation. he understands there's much more work to do to redeem the soul of america. that is why as president he has set his hand to the plow to bring change to america by ending two wars and bringing about comprehensive health care reform. thank you, mr. president. [ applause [ applause ] >> now, my dear friends, it is my great honor and pleasure to present our friend, our preside president, president barack obama, and the first lady.

[ cheers and applause ] >> thank you. thank you very much. thank you so much. thank you. thank you very much. thank you. please, please have a seat. thank you. thank you very much. please, please. what a singular honor it is for me to be here today. i want to thank first and foremost the johnson family for giving us this opportunity and the graciousness with which

michelle and i have been received. we came down a little bit late because we were upstairs looking at some of the exhibits and some of the private offices that were used by president johnson and miss johnson. michelle was, in particular, interested in a recording in which lady bird is critiquing president johnson's performance. and she said, come, come, you need to listen to this. and she pressed the button and nodded her head. some things do not change. even 50 years later. to all the members of congress, the warriors for justice, the elected officials and community leaders who are here today, i

want to thank you. four days into his sudden presidency, and the night before he would address a joint session of the congress in which he once serv served, lyndon johnson sat around a table with his closest advisors, preparing his remarks to a shattered and grieving nation. we wanted to call on senators and representatives to pass a civil rights bill. the most sweeping since reconstruction. most of his staff counseled him against it. they said it was hopeless. that it would anger powerful southern democrats and committee chairm chairman, that it risked derailing the rest of his

domestic agenda. one particularly bold aide said he did not believe a president should spend his time and power on lost causes, however worthy they might be. to which it is said president johnson replied, well, what the hell's the presidency for? [ applause [ applause ] >> what the hell's the presidency for? if not to fight for causes you believe in. today, as we commemorate the 50th anniversary of the civil rights act, we honor the men and women who made it possible. some of them are here today. we celebrate giants like john

lewis. andrea young and julian bonnet. we recall the countless unheralded americans, black and whi white, students and scholars, preachers and housekeepers whose names are etched not on monuments but on the hearts of their loved ones and in the fabric of the country that they helped to change. but we also gather here deep in the heart of the state that shaped them to recall one giant man's remarkable efforts to make real the promise of our found i ing. we hold these truths to be self-evident, that all men are created equal.

those of us who have had the singular privilege to hold the office of the presidency know well that progress in this country can be hard and it can be slow. frustrating and sometimes you're stymied. the office humbles you. you're reminded daily that in this great democracy, you are but a relay swimmer in the currents of history, bound by decisions made by those who came before. reliant on the efforts of those who will follow to fully vindicate your vision. but the presidency also affords a unique opportunity to bend those currents. by shaping our loss and by shaping our debates. by working within the confines of the world as it is but also

by reimagining the world as it should be. this was president johnson's genius. as a master of politics in the legislative process, he grasped, like few others, the power of government to bring about change. lbj was nothing if not a realist. he was well aware the law alone isn't enough to change hearts and minds. a full century after lincoln's time, he said until justice is blind to color, until education is unaware of race, until opportunity is unconcerned with the color of men's skins, emancipation will be a proclamation but not a fact. he understood laws couldn't accomplish everything. but he also knew that only the law could anchor change and set

hearts and minds on a different course. and a lot of americans needed the law's most basic protections at that time. as dr. king said at the time, it may be true the law can't make a man love me but it can keep him from lynching me and i think that's pretty important. [ applause ] and passing laws was what lbj knew how to do. no wone knew politics and know one loved legislating more than president johnson. he was charming when he needed to be, ruthless when required.

he could wear you down with logic and argument, he could horse trade and he could flatter. you come with me on this bill, he would reportedly tell a key republican leader from my home state during the fight for the civil rights bill, and 200 years from now school children will know only two names, abraham lincoln and evert dirkson. [ laughter ] >> and he knew that senators would believe things like that. [ applause ] president johnson liked power. he liked the feel of it, he wielding of it. but that hunger was harness ed

and redeem ed by a deeper understanding of the human conditi condition, by a sympathy for the understood dog, for the downtrodden, for the outcast. and it was a sympathy rooted in his own experience. as a young boy growing up in the texas hill country, johnson knew what being poor felt like. poverty was so common, he would later say, we didn't even know it had a name. the family home didn't have electricity or indoor plumbing. everybody worked hard. including the children. president johnson had known the metallic taste of hunger, the feel of a mother's calloused

hands, rubbed raw from washin and cleaning and holding the household together. his cousin, a ava remembered swt ers days on her hands and knees in the cotton fields with lyndon beside her, boy, there's got to be a better way to make a living than this, there's got to be a better way. it wasn't until years later, when he was teaching at a so-called mexican school, in a tiny town in texas, that he came to understand how much worse the p persistent pain of poverty could be for other races in the jim cr crowe south. oftentimes his students would show up to class hungry. when he'd visit their homes he'd meet fathers who were paid slave

wages by the farmers they worked for those children were taught, he would later say, the end of life was in this beet row, spinach field or cotton patch. deprivation and discrimination, these were not abstraction to lyndon baines johnson. he knew poverty and opportunity are as inseparable as opportunity and justice are joined. so that was in him. from an early age. now, like any of us, he was not a perfect man. his experiences in rural texas may have stretched his moral imagination but he was ambitious. very ambitious. a young man in a hurry to plot

his own escape from poverty and to chart his own political career. and in the jim crow south, that meant not challenging convention. during his first 20 years in congress, he opposed every civil rights bill that came up for a vote, once calling the push for federal legislation a farce and a shame. he was chosen as a vice-presidential nominee in part because of his affinity with an ability to deliver that southern white vote. and at the beginning of the kennedy administration, he shared with president kennedy a caution towards racial controver controversy. but marchers kept marching. four little girls were killed in a church. bloody sunday happened.

the winds have change blew. and when the time came, when lbj stood in the oval office, i picture him standing there, taking up the entire door frame looking out over the south lawn. in a quiet moment and asked himself what the true purpose of his office was for. what was the end point of his ambitions? he would reach back in his own memory and he would remember his own experience with want and he knew he had a unique capacity as the most powerful white politician from the south to not

merely challenge the convention that had crushed the dreams of so many but to ultimately dismantle for good the structures of legal segregation. he's the only guy who could do it. and he knew there'd be a cost. famously saying, the democratic party may have lost the south for a generation. that's what his presidency was for. that's where he meets his moment. and possessed with an iron will, possessed with those skills that he had honed so many years

congress, pushed and supported by a movement of those willing to sacrifice everything for their own liberation president johnson fought for and argued and horse traded and bully ied d persuaded until ultimately he signed the civil rights act into law. and he didn't stop there. even though his advisors again told him to wait, again told him, let the dust settle. let the country absorb this momentous decision. he shook them off. the meat in the coconut, as president johnson would put it, was the voting rights act.

so he fought for and passed that as well. immigration reform came shortly after. and then a fair housing act. and then a health care law that opponents described as socialized medicine that would curtail america's freedom but ultimately freed millions of seniors that the fear of illness could rob them of freedom and security in their golden years which we now know as medicare. [ applause [ applause ] >> what president johnson understood was that equality required more than the absence of oppression. it required the presence of economic opportunity. he wouldn't be as eloquent as dr. king would be in describing

that link aage, as dr. king mov into mobilizing sanitation workers and poor people's moveme movement. but he understood that connection because he had lived it. a decent job. decent wages. health care. those two were civil rights worth fighting for. an economy where hard work is rewarded and success is shared, that was his goal. and he knew, as someone had seen the new deal transform the landscape of his texas childhood, who had seen the difference electricity had made because of the tennessee valley authori authority, the transformation concretely day in and day out in the life of his own family, he understood that government had a

role to play in broadening prosperity to all those who would strive for it. we want to open the gates to opportunity, president johnson said. but we're although going to give all our people, black and white, the help they need to walk through those gates. some of this sounds familiar, it's because today we remain locked in this same great debate. about equality and opportunity. and the role of government in insuring each. as was true 50 years ago, there are those who dismiss the great society as a failed experiment and an encroachment on liberty, who argue the government has become the true source of all

that ails us and poverty is due to the moral failings of those who suffer from it. they're also those who argue, john, that nothing's changed. that racism is so embedded in our dna that there's no use trying politics. the game is rigged. but such theories ignore history. yes, it's true that despite laws like the acrocivil rights act a voting rights act and medicare, our society is still racked with division and poverty, yes, race still colors our political debates. and there have been government

programs that have fallen short. in a time when sin simcynicism often passed off as wisdom it's easy to conclude there are limits to change, that we are trapped by our own history and politics is a fool's errand, and we'd be better off if we rolled back big chunks of lbj's leg it wassy, or at least if we don't -- lbj's legacy or if we don't put too much of our hope, invest too much of our hope in our government. i reject such thinking. not just because medicare -- [ applause [ applause ] >> not just because medicare and medicaid have lifted millions from suffering, not just because

the poverty rate in this nation would be far worse without food stamps and head start and all the great society programs that survive to this day, i reject such cynicism because i have lived out the promise of lbj's efforts, because michelle has lived out the legacy of those efforts, because my daughters have lived out the legacy of those efforts, because i and millions of my generation were in a position to take the baton that he handed to us. [ applause [ applause ] >> because of the civil rights movement, because of the laws president johnson signed, new doors of opportunity and education swung open for everybody. not all at once but they swung open. not just blacks and whites, but

also women and latinos and asians and native americans and gay americans and americans with a disability. they swung open for you and they swung open for me. [ applause ] >> that's why i'm standing here today, because of those efforts, because of that legacy. that means we've got a debt to pay. that means we can't afford to be cynical. half a century later, the laws lbj passed are now as fundamental to our conception of ourselves and our democracy as the constitution and the bill of rights. they are foundational.

an essential piece of the american character. but we are here today because we know we cannot be complacent. for history travels not only forwards, history can travel backwards. history can travel sideways. securing the gains this country has made requires the vigilance of its citizens. our rights, our freedoms, they are not given, they must be won. they must be nurtured through struggle and discipline and persistence and faith. one concern i have sometimes during these moments, the celebration of the signing of the civil rights act, the march on washington, from a distance,

sometimes these commemorations seem inevitable, they seem easy. all the pain and difficulty and struggle and doubt all that's rubbed away, and we look at ourselves and say things are too different now. we couldn't possibly do what was done then, these giants, what they accomplished, yet they were men and women, too. it wasn't easy then. it wasn't certain then. still, the story of america is a story of progress. however slow, however incomplete, however harshly challenged at each point on our

journ journey, however flawed our leader leaders, however many times we have to take a quarter of a loaf or half a loaf the story of america is the story of progress. and that's true because of men like president lyndon baines johnson. [ applause ] in so many ways he embodied america, with all our gifts and all our flaws. in all our restlessness and all our big dreams. ms. man, born into poverty, w n

weaned in a world full of racial hatred somehow found in himself the ability to connect his experience with the brown child in a small texas town. the white child in appalachee. the black child in watts. as powerful as he became in that oval office, he understood then, 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. [ applause ]

and those children were on his mind when he strode to the podium that night in the house chamber, when he called for the vote on the civil rights law. it never occurred to me, he said, in my fondest dreams, that i might have the chance to help the sons and daughters of those students that he had taught so many years ago, and to help people like them all over this count country. but now i do have that chance. and i'll let you in on a secret, i mean to use it. and i hope that you will use it with me. [ applause ] that was lbj's greatness.

that's why we remember him. and if there is one thing that he in this year's anniversary should teach us, if there's one lesson i hope malia and sasha and young people everywhere learn from this day, with enough effort and uf empathy and enough p perseverance and enough courage, people who love their country can change it. in his final year, president johnson stood on this stage, racked with pain, battered by the controversies of vietnam, looking for older than his 64 yea years, and he delivered what would be his final public spe h speech. we have proved that great progress is possible, he said. we know how much still remains

to be done. and if our efforts continue, and if our will is strong, and if our hearts are right, and if courage remains our constant companion, then my fellow americans, i am confident we shall overcome. [ applause ] >> we shall overcome. we, the citizens of the united states. like dr. king, like abraham lincoln, like countless citizens who have driven this country in ex sorably forward, president johnson knew that ours in the end was a story of optimism, a

story of achievement and constant striving that is as unique upon this earth. he knew because he had lived that story. he believed that together we can build an america that is more fa fair, more equal and more free than the one we inherited. he believed we make our own destiny. and in part because of him we must believe it as well. thank you, god bless you. god bless the united states of america. [ applause ] >> that was president obama addressing the audience there at the 50th anniversary commemoration of the civil rights act, the passage of it. there with john lewis, congressman who was one of the key leaders of the civil rights movement, along with martin lu

th luther king junior, the national correspondent, susan malveaux was outside the library able to watch the president's speech. it's not first time he's addressed civil rights. three months ago we heard him at the 50th anniversary at the march on washington. this was a little bit different talking about lbj's legacy. what struck you as unique here? >> he said the presidency, what the hell is the presidency for but to make big changes here? it's been one of those points of debate. president obama is one of four presidents when the summit is over we will hear from. we will hear from george w. bush later. one of the things people have been talking about, how do we bring about change of a country? is it possible to replicate what happened 50 years ago such a tumultuous time. and we heard from president

carter and said you need to establish relationships between the president and congress to move big agenda items forward. we heard from president clinton yesterday saying people don't have the kind of courage those legislators had 50 years ago to potentially lose their seats to get big items done. those are the things they need. not to understate this, this president, lbj, was backed by a movement of people. i had a chance to talk to the ambassador, andrew young. he said that was part of it, too, the events on the ground and so many people were pushing the president he had to do something, he had to act. that's the kind of thing this president needs in some ways, a ground swell, a movement to demand congress and the president ultimately work something to get something done because things are broken in washington. the president brought it home. he brought it in a very personal way. he owes where he is today to lbj's legacy but also to that

movement, the people on the ground that actually made that happen. >> suzanne malveaux for us in austin. thank you so much. coming up, important new details in this mystery of malaysian airlines flight 370, we now know who said good night to the air controllers. we'll talk about what that means for the investigation next. i dbefore i dosearch any projects on my home. i love my contractor, and i am so thankful to angie's list for bringing us together. find out why more than two million members count on angie's list. angie's list -- reviews you can trust. how much money do you think you'll need when you retire? then we gave each person a ribbon

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>> all right we want to get you up to speed. a search plane has detected another signal that could be from the jet liner's black boxes. the signal was picked up from an australian plane. experts currently analyzing that signal and flight 370's captain was the last person to speak to air traffic controllers. an official says there was nothing unusual, no third party voice heard in the cockpit and sources say that flight 370 disappeared from military radar after crossing back over malaysia. that means it must have dipped as low as 4,000 or 5,000 feet. we have mark weiss, peter gold, and tom fuentes, former fbi

assistant director. this is fascinating, gentlemen. it seems like there is agreement here, this idea that the plane may have dropped to 4,000 feet. we shouldn't take it as gospel. that's what you say? >> we really don't know what the altitude was. nothing has confirmed that. it is all speculation. >> what do you think, peter? why can't we take it to the bank? >> when you're looking at the primary radar track, there is is a high degree of error in the -- it is simply speculation. >> so it's not necessarily an attempt to avoid radar? >> when we don't know that that is what it actually did, then we can't say why it did it or what the motives were. >> the other thing that i find very interesting, mark, is let's say that the plane did drop to 4,000 feet and then it would have had to come back up, right?

>> fantasy. >> you're not going to take a 777 and take it from 35,000 feet to 4,000 feet in the space of 120 miles and bring it back up to 35,000 feet. it just isn't going to happen. >> we're hearing from sources that the malaysian air force scrambled the planes, they didn't tell aviation officials or search and rescue operations for three days. does this just add to our concerns? >> it's not about the investigation, but i think it adds to the concerns that malaysia is not a very safe place because if it takes their air defense that many days to figure out what they had come across their sky, that's incredible to me. and now we hear 30 some days later that they scrambled jets or maybe it was rescue planes and we don't know that. they sent someone allegedly to the south china sea and others to the south and west. i mean, there has just been a

set of conflicting storyies now to say they finally figured out what their radar said sounds to me like it's one more story and why should this one be any truer? >> we now understand the latest is that it was who? >> we now say it's the pilot. >> the captain, right? not the first officer. >> this reinforces that from the beginning the malaysian government has had a hard time coordinating its information that it had and making it available in a truthful way. it undercuts the credibility of the government and its investigation. >> and it doesn't mean anything when we hear from sources necessarily that we didn't hear anything besides the captain's

voice. >> if you are talking directly into a microphone you would not have heard if there were someone else in the cockpit. we don't know. >> microphones have fields of what they pick up. uni directional, you won't hear what is happening. >> somebody behind you could have been having a conversation and you wouldn't have heard it. >> mark, peter, tom, thank you so much for being with us and talking about this and explaining it all for us. that is it for me. newsroom with brooke baldwin starts right after a quick break.

>> hi there, i'm brooke baldwin. breaking news on the mystery of flight 370. here we are now day 35 and the story is changing. we now have explosive new planes from a senior malaysian government official. so here is what the sources were telling cnn. that after the plane took that mysterious hair pin turn to the left, watch the red line, and here comes the left turn, it then disappeared from radar, flying about 120 nautical miles off the grid and according to data the only way it could have avoided detection like this is if it made a rapid decent in altitude. but as to whether this was a deliberate act to avoid radar detect