wear shorts. no jeans this weekend. shorts weather. >> how do you not know i'm wearing shorts behind the anchor desk. >> you just gave it away. >> no, i'm not. on the broadcast tonight, deliberate act. a growing consensus among experts that whatever happened aboard that missing airliner appears to be intentional. tonight, what investigators uncovered a week since it vanished. on the brink. russian forces exert total ntrol in crimea on the eve of a controversial vote to break away from ukraine. richard engel is there as the world braces for what happens next. breakthrough. a once in a generation effort to break through a freeze on the great lakes. we're on board for the mission. and against all odds. a mother who never gave up searching for the daughter she lost so long ago. tonight, their incredible reunion.

"nightly news" begins now. good evening. brian is off tonight. i'm lester holt. as we reach the one-week mark in the search for that missing malaysian jet, experts agree that what we are witnessing is unprecedented in modern aviation history, a large airliner, packed with people, far from where it was supposed to be and then vanishing without a trace. ing tonight there is new information showing the boeing 777 made not one, but two changes of course after it vanished from radar screens. and that has dramatically shifted the focus of search efforts while at the same time expanding the possibilities of where the plane ended up. so much about this flight simply doesn't add up. but that which does has investigators tonight accepting the real possibility that

someone deliberately flew this plane into danger. nbc's tom costello leads us off again tonight. tom, i know they have been analyzing some data. what is it now telling us about the path of the jet? >> reporter: investigators are trying to determine if it headed north or south over the indian ocean. to do that, they're using brand-new technology to trace an electronic ping off a satellite, similar to your cell phone pinging a tower even when you're not communicating. but that trace may only narrow the search zone to hundreds, perhaps thousands of miles. more than seven days as flight 370 disappeared, and still no firm sign of where the 777 with its passengers and crew might be. malaysian authorities today laid out some of the possibilities. >> it could have been done intentionally. it could be done under duress. it could be done because of an explosion. so that's why i do not want to go to the realm of speculation. >> reporter: here is what investigators have. the military radar tapes showing the plane left its flight path,

made a deliberate u-turn and head west over the strait of malacca. the acars data, the plane's automated data reporting system stopped transmitting data at 1:07 p.m. the pings. the plane did continue to send automated pings once an hour to an oshl orbiting satellite. they were received in london that said in a statement routine automated signals were received during its flight from kuala lumpur. now investigators hope to use those pings to calculate where the plane might have flown in four to five hours. >> and hopefully with more work on the data and more refinement if you will, they can get a very good idea where the aircraft went. >> reporter: the new massive search zone now stretches from the strait of malacca to the bay of bengal where the u.s. navy is searching. the uss kidd is now in the area as well. an anti-submarine plane loaded with underwater search technology should start working tomorrow. we talk to commander william marks. >> there is no way you can

search the entire indian ocean. a ship is an amazing platform, but it can't be done with ships alone. and even our p3 and p 8 with a range of a thousand or so miles, they'll have to return. >> reporter: if they ever find the wreckage, the black boxes will be critical to uncovering what happened. the fdr should hold 24 hours of plane data. >> the flight data recorder will tell us hundreds if not thousands of parameters that are recorded on the airplane, what the airplane physically did. >> reporter: but the cockpit voice recorder only holds the last two hours, which means we may never know what happened in the cockpit that caused flight 370 to turn around. investigators are also looking at what was in the cargo hold in the plane. was there some explosive or flammable cargo on board. they're looking at this as well. lester? >> tom costello, thank you. and if you keep with the theory that it was a deliberate act, you have to assume everybody on

the plane is under investigation, passengers and crew as authorities explore all possibilities trying to determine who might have had a motive and the ability to commandeer that plane. nbc's keir simmons has more. >> reporter: as the search for flight 370 continues, malaysian officials are now looking at how the plane could have disappeared, and who might be involved, including the crew. the flight's captain in his 50s, highly experienced. he had logged 18,000 flight hours. his copilot, farik hamid, 27, relatively new, with 2800 flight hours. both are being investigated, but so is everyone on board. the key questions, who else on board could fly a 777 who might have a motive to commandeer the aircraft and for what purpose. and if the plane was hijacked, where was it going? during the crucial first hour of the flight, there would have been an opportunity to break

into the cockpit despite security precautions. >> if there were to be a real takeover, that would be the time where the crewmembers would be moving in and out to serve the cockpit the drinks. >> reporter: there were prayers for flight 370 today at the co-pilot's local mosque. friends here call him a quiet, respectful man, living with his parents in this middle class home. less is known about the pilots seen here at home improvement videos. he has a flight simulator at home. a man dedicated to flighting. but malaysian officials aren't telling us much more than that. so the wait for answers continues. so painful for family and friends of those on board. here at the airport they fill this wall with prayers and messages of hope for loved ones. they may never see again. keir simmons, nbc news, kuala lumpur.

we now want to bring in aviation expert greg feith, a senior safety director with the national transportation safety board and a veteran pilot. let's put to the side for a moment the question of who was flying the airplane. we heard in tom's reports they're looking at two possible course changes, one to the north and one to the south. if you're trying to escape detection, what is the more likely route? >> lester, the more likely route is the southern route. once you cross that little peninsula, now you're in open ocean. there is no radar coverage down there. it is a vast, vast ocean, going almost as far down as the south pole. >> and in fact we looked at this graphic down there. it points down off the coast at australia. should they be searching in that part of the world now? does the search area become that big? >> i think so. they're going to have to put assets down this since now they have a north track and a south track. and i would be looking primarily in the south track. in fact, with australia being down there, i may even request

basically help from australia to assist in the search of that part of the ocean. >> you know, i said earlier today, we've gone past the far-fetched point of this. everything is kind of on the table. and we talked about whoever took it maybe wanted to land somewhere. if you took that southern route, there is no place to go. >> there is no place. it is open ocean. you can land it in the water. but if you're going that direction and your intent basically is to just do something bad to the aircraft, that's the place to do it because if that airplane even breaks up and sinks, that's a vast part of the ocean and the world. you may never, ever find the main wreckage. you may find some floating debris at some point, but that is the place to get rid of the airpt airplane. >> can't recall a head scratcher like this one. >> nope. an update on while we were on the air last night. an incident of a different nature. officials say an accident on the runway at philadelphia international airport happened when a tire, a front landing

gear blew out on a us airways jet. it was headed from florida. it forced the pilot to abort takeoff. there were no reports of any serious injuries. the crippled plane was removed from the runway. it's now in a hangar where it will be examined by investigators. and in new york city officials say they have recovered all of the victims after that massive building explosion earlier this week. and all the miss having been accounted for. the final death toll stands at eight with some 60 people injured. a key turning point of the crisis in ukraine is coming this weekend. voters head to the polls for a controversial referendum over crimea. but with diplomatic efforts stalled and russian troops firmly in control in crimea, some say the outcome is already decided. nbc's chief foreign correspondent richard engel managed to make his way to crimea. he joins us from there tonight. richard, good evening. >> reporter: good evening, lester. in some ways, this referendum is a moot point. russian forces already control

crimea. they took it without a fight, and they won't give it up. for now, crimea is still part of ukraine. but these men have already sworn allegiance to russia. and today showed their strength under a statue of lenin in simferopol, crimea's biggest city. they are tough looking, ragtag bunch, armed with clubs and dressed in whatever they can get their hands on. these men and their russian backers now run things here. and many crimeans believe the upcoming referendum is just a rubber stamp for a takeover by force that's already happened. a takeover accomplished by thousands of russian troops controlling bases, airports, and other key facilities. and many crimeans are happy they're here. russia has popular support in crimea. irena, a psychologist told us crimea was once the jewel of the

soviet union. there are voices of dissent. but they're faint. a few hundred today marched to keep crimea part of ukraine. but they held their demonstration by a roadside, run out of town by the pro russian militias. do you think that crimea is now occupied by russia? >> yeah. obviously it's occupation. >> reporter: but this isn't just about crimea anymore. russia has mobilized 10,000 troops near ukraine's border. ukraine showed off its weapons too, but they're no match for the russian forces many worry may be coming for eastern ukraine next. already clashes have broken out there. russia's foreign minister told secretary of state kerry today his country's troops will go no further into ukraine. but their faces show frustration and deep mistrust. here in crimea, the facts are

clear. the russian flag flies over parliament, the building under guard. president obama today again threatened sanctions. diplomats tell us they're not so much about trying to pry crimea away from russia. even u.s. officials acknowledge that's unlikely, but more about trying to deter russia from going any further. lester? >> richard, thank you. and an update now on our special series "syria and the children of war." you might recall dr. nancy snyderman told us about the premature twins born at a hospital along the syria-lebanon border. one died at childbirth, and sadly, we've now learned that the second baby has also died, in part because of breathing complications. as for the 19-month-old girl who doctors feared might have polio, they're still waiting for final test results, but they say her paralysis could be the result of a small brain hemorrhage, and may be treatable. they're cautiously optimistic she will walk again.

still ahead tonight, historic freeze. the amazing mission to break the ice on the great lakes after the kind of winter not seen in decades. and later, they're not done yet. another big day for team usa in sochi.

we probably don't need to remind you that it's been a long and brutal winter, and all those storms and frigid temps didn't just make a mess of the country's roads, rails and skies, it's also snarled traffics on key rivers and

lakes, including the great lakes. 92% of them were covered in ice, and clearing those shipping lanes is no easy tax. we get our report tonight from nbc's john yang. >> reporter: the first thing you notice is the sound. a constant deep rumble as the u.s. coast guard cutter alder breaks up ice that has covered lake superior for months. conditions are hard for the crew, single digit temperatures and winds topping 25 knots. and for the vessel. >> you hear the vessel shaking right snow? bolts come loose, pipes freeze. >> reporter: off duluth, minnesota, the 295 foot alder pushes through ice as thick as four feet, freeing these one thousand-foot ore carriers, literally frozen in place. >> without the icebreakers making the ports ready for commerce, it wouldn't move until the ice is essentially gone. >> reporter: the ship's reinforced bow drives on to the

ice, crushing it under the weight. this concrete block weighs 16,000 pounds. it's one of three on the deck here to give the alder extra weight as it breaks through ice up to several feet thick. it's among nine coast guard breakers on the great lakes turning plates of ice into smaller chunks that can be swept away by the wind. but the wind can also blow the ice back into shipping lanes and harbors. >> it just -- the force. it's a force of nature. >> reporter: the great lakes dominate the region's culture, economy, and climate. they'll likely feel the effects of the ice well into summer. >> it's going to be -- i hate to say it, a lousy year for swimming here until about august. >> reporter: plus, water levels are projected to return to normal after recent record lows. but forecasters say it will be weeks before all this ice melts. until then, the men and women of the alder will be outbreaking it up. >> the worst ice we've seen in about 25 years. once in a generation kind of thing. >> reporter: a crucial mission

for so many who live, work, and play on the great lakes. john yang, nbc news aboard the coast guard cutter on lake superior. we're back in a moment with the news today about an iconic american image.

we learned today that glenn mcduffie has died. he was a navy veteran of world war ii and one of several men over several decades claimed he was the sailor seen kissing the nurse in the iconic life magazine photo taken in times square celebrating japan's surrender. mcduffie's daughter said he only came forward after others claimed to be the sailor. he was changing trains in new york when he learned the war was over. he was so happy that he ran into the street and planted a kiss on a stranger. glen mcduffie was 86 years old. and tough times continues for people in the food business. quiznos says they have filed for

bankruptcy to get out of $400 million in debt after losing ground to competitors like subway. the announcement comes days after pizza chain sbarro, a familiar sight in malls and airports filed for bankruptcy for the second time in three years. paris is seeing some of its worst pollution in years, with the eiffel tower only visible through a thick blanket of smog today. forecasters point to warmer weather, stagnant air, and a high number of diesel vehicles. the city of lights is encouraging people not to drive, instead offering free rides on transportation. back on sochi, it was a good day for americans in the paralympics. the american men swept the snowboard cross, with 27-year-old evan strong who we featured on this broadcast claiming the gold. it is the first gold for team usa at this paralympic games. meanwhile, our hats are off to another competitor who we also kept our eye on, tatyana mcfadden won silver. in the 1 kilometerer sprint

wednesday, proving it's never too late. the wheelchair racer only took up cross country skiing about a year ago. and one last note, the the u.s. and russia hockey rivalry is renewed once again. the two men's teams will square off tomorrow for the gold medal. you can catch it at noon eastern time here on nbc. when we come back, a dream come true for one mother two decades in the making.

our final story tonight is about the incredible reunion of a mother and daughter who lost each other decades ago torn apart by war. you're about to meet a pair of brave women who never lost hope. we want to thank our nbc station kusa in denver for bringing this remarkable story to our attention. we get our report from nbc's ann curry. >> reporter: amira ali is nervous, with tears and joy. about to meet a daughter she thought had died long ago. >> the dream is coming true. >> reporter: she last saw her little girl 24 years ago when their village was attacked one night in sudan's brutal war. in the dark and the chaos, amira lost her 6-year-old daughter tina. believing tina was killed, amira

fled with her other children, walking for days before joining the millions in refugee camps like the one we visited in 2006. >> what do you miss about being home? >> reporter: years later, amirrah made to it denver, starting a new life, studying english to become an american citizen. but she never stopped grieving for teen. that one day after a friend urged her to join facebook, the message that would be the shock of her life. >> i don't know what i do. i see her, i can't believe it. >> she came to me and said my daughter is alive. i found her through facebook. >> reporter: george brown is amirrah's english teacher. >> i just stopped and said wait a minute, wait a minute, let's back up. >> reporter: not only was tina alive, she was also moving to the u.s. having just been granted asylum to escape the violence still raging at home. and it turned out that amira's sister, who amira also thought had died, had raised tina.

>> i'm so very, very happy. it is a long time to see my mom. like i dream now when i see her, i cannot believe. but i'm happy. >> reporter: reunited with the daughter she thought had died, amira met a grandson she didn't know she had. >> god bless america. >> reporter: tonight in america, a family is singing. ♪ i'm so glad jesesus loves me ♪ >> reporter: knowing that even when all hope seems lost, joy can be found. ann curry, nbc news. that's our broadcast for this friday night. thank you for being with us. i'm lester holt in for brian. i'll see you later tonight for dateline, tomorrow morning on "today," and then right back here tomorrow night. have a good night, everyone.

. we still have faith and confidence that we'll get answerens and justice. >> the pather of a mi ee eer -- missing teenager shares hope, determination, and grief i'm jessica aguirre. >> i'm raj mathai. sierra's body has never been found and her accused killer

sits in jail awaiting his trial and her father continues his search. marianne favro spoke to steve lamar today. such a difficult journey. what's the family's reaction at this point. >> reporter: he is frustrated by how long this case is taking to prosecute in the courts. he is also frustrate that despite hundreds of searches, two years later, he still has no answers. two years ago this sunday, 15-year-old syrierra lamar disappeared after leaving her home in morgan hills. she has never been found. today her father talked to nbc bay area about the painful anniversary. >> it's even tougher, i think, these days just, you know, the frustration of it all and stuff, just kind