on our broadcast tonight, turning point. new information about the moment that missing airliner went off course, raising new questions about the pilot's intent and whether this disappearance was planned. out of the sky. an awful tragedy in the heart of seattle. a local news helicopter comes crashing down, exploding in flames on the streets below. our nbc news investigation, how general motors quietly changed the design of defective ignition switches, but didn't get the word out until it was too late. and long overdue. an emotional day at the white house as 24 heroic veterans are awarded their nation's highest honor. the recognition they were denied for far too long. "nightly news" begins now.

>> announcer: from nbc news world headquarters in new york, this is "nbc nightly news" with brian williams. good evening. a number of new theorys have emerged about what might have happened to that missing jumbo jet, gone from sight for 11 days now. the problem with all of them remains the single most tragic fact, there's no accounting for the 239 missing souls on board the aircraft. while a lot of the debate is about electronics and radar signatures and altitudes and flight paths, there remains an awful lot of area to be searched and a massive aircraft has so far managed to disappear without a trace for over a week now. we get the very latest on the investigation including some new details tonight on the crucial turn in the flight from nbc's tom costello in our d.c. newsroom. tom, good evening. >> hi, brian. we knew that whoever planned the u-turn in the plane, did so with the help of the on board computer.

tonight we learned when the turn was programmed in. at least 12 minutes before the co-pilot calmly said good night to the air traffic controllers. that would further indicate the you h turn was planned and executed in the cockpit before the controllers lost contact. tonight, nbc news has learned that flight 370's u-turn was manually programmed into the computer in the cockpit. that means the u-turn was premeditated. executed only the last radio call and after the transponders went dead. if the pilot entered that turn, why? >> some pilots will program in an alternate flight plan in the event of an emergency. we don't know what the reason was for this time flight plan, whether to go back to kuala lumpur or to take it back from beijing. >> reporter: a retired captain helped re-create in a 737 what we know, someone turned off the

transponder with the flip of a switch. >> you can see i can push the button and that would bring it up. >> reporter: they switched off, then disabled the acars data system, possibly by pulling the circuit breaker. >> the circuit breaker would be on one of these pack panels, behind the pilots. >> reporter: easy steps for a pilot. total time, 20 seconds. then making a you-turn back to kuala lumpur. >> all i have to do is spin this knob around and the aircraft will turn around. >> reporter: sources tell nbc news whoever turned the plane programmed the flight management system and knew what they were doing. >> this would be a very elaborate scheme. they would have had very, very extensive training to pull this off. >> reporter: meanwhile, the most intense search remains focused on the rough waters over the southern indian ocean. 1,500 miles southwest of perth, where a massive 370,000 square

mile area simply too big for an underwater sonar search. malaysian authorities say searches of the homes and even a flight simulator turned up nothing suspicious. tonight with the flight crew under the microscope, the family of the captain released these images showing the man they love. and there's this, thailand today said its radar did pick up a plane that might have been flight 370 early in the morning on march 8th. that's not surprising since the malacca strait borders thailand. when asked why they didn't provide the information sooner they simply said, because they weren't asked. brian? >> continues to be a remarkable mystery, day 11. tom costello starting us off from d.c. tom, thanks. again tonight we saw him in our setup piece, we turn to greg feith. he's senior air safety director, a veteran pilot himself.

greg, this left turn had to be manually punched in in the cockpit, knowing what we know about you pilots, it's in your blood, whether you fly a single engine or a wide body to always know where you go in case of trouble, sometimes it's behind you, below you, out in front of you. always cognizant of where to go in case of trouble. why wouldn't this be consistent with a captain who perhaps had trouble on board? >> it could be, brian. we just don't have enough information. it's possible they programmed in their alternate plan. that is, if they had taken off, had a problem, all they would have to do is pull up that stand by flight plan, put it in the active window, hit execute to come back to kuala lumpur. or they could have put in a stand by flight plan to take the plane away from beijing and return to kuala lumpur and put it in a phantom waypoint all the way down into the south indian ocean and continue to let the plane fly that direction.

thank you, we'll continue to let this continue. we'll have more from greg, tom, our team of journalists covering this investigation their updated work on our website tonight. it will remain there at nbcnews.com. also making aviation news today, a local news helicopter crashed shortly after takeoff, landing on cars below, all of it right in front of the city's landmark space needle. we get our report tonight from nbc's miguel almaguer. >> oh, my god. >> reporter: witnesses in downtown seattle could do little to help. these pictures taken moments after impact. >> we're responding to 400 broad street. >> reporter: the news helicopter plunged off the tv station's roof into the busy streets below during rush hour. burning in the shadow of seattle's iconic space needle. only the chopper's tail section was recognizable. >> the aircraft was lifting off

the helipad at fisher plaza. something went horribly wrong. >> reporter: the crew inside, an experienced pilot and long time photographer working for komo television were pronounced dead at the scene. tonight ntsb investigators are combing through the wreckage. >> we're looking at everything, the environment, the weather, the pilot. >> reporter: one man in serious condition crawled out of this burning car. >> his head was bleeding, his shirt was on fire and he collapsed. >> get back. >> reporter: construction workers tried to keep people away, as jet fuel poured through a downtown street. >> stay away from the fuel, get back. >> reporter: the tragedy could be seen from newsroom windows where the victims worked. a horrific sight for colleagues who are now covering the news. >> we heard the explosion as the chopper hit the ground. >> reporter: tonight in seattle, answers to what caused the crash may not come for weeks. >> this is one of the last shots taken of the helicopter this morning, framed against a

rainbow. it's hard to put into words what that image means. >> reporter: tonight colleagues struggle to say good-bye. miguel almaguer, nbc news, los angeles. in moscow today, just like that, vladimir putin signed a document and made it official and now tonight crimea belongs to russia. even though the u.s. is calling this a land grab, there's nothing anyone can do about it, and the majority of local opinion seems to support it. and for the two leaders here, putin and obama of the u.s., they now seem to be assuming public roles we haven't seen since the cold war. we get our report tonight from our chief foreign affairs correspondent andrea mitchell. >> reporter: vladimir putin today emotional, strident, delivering his version of russian history to a cheering kremlin crowd. accusing the u.s. of breaking promises. expanding nato to russia's borders. cheating over and over. and in red square, declares that crimea is finally heading home

to russia. while putin's deputies ridiculed the u.s. sanctions in tweet's addressed to comrade barack obama, when in crimea's capital, the exchange turned deadly. gunmen dressed in russian military uniforms stormed a base, killing a ukrainian soldier, the first known casualty of the conflict. russia seemingly oblivious to u.s. and european threats for consequences for annexing crimea. >> putin is dug in, i mean, this speech today was really over the top, and in my opinion, really ends the post cold war era. >> reporter: flying overnight to calm ukraine's neighbors, nato's newest members, the vice president sounded like a cold war era, accusing putin of a brazen land grab. many argue putin would have gone after ukraine no matter who was in the white house. any cooperation with russia on syria or iran? >> there's no question that if we have a rupture in our relationship with russia, there are going to be costs elsewhere in the world.

>> reporter: and there are political costs for the president at home. >> every day, every moment that he's working on a foreign policy issue, no matter how pressing, is a moment he's not focusing on the economy, in the minds of people. and that is their number one issue. >> reporter: so far, the only clear political winner seems to be in moscow. andrea mitchell, nbc news, washington. president obama told the assembled honored guests at the white house this afternoon, this is going to take a while and it did. because today the president on behalf of a grateful nation presided over the largest single group of recipients of the medal of honor since world war ii. here are the names of the 24 recipients awarded today. in many cases they were denied the nation's highest military award because of their race or religion. and of the 24, from three separate wars, only three men survived. and they stood together today. sons and daughters accepted for the deceased heroes and for many the ceremony was overpowering,

several were comforted by the president. our report tonight from our pentagon correspondent jim miklaszewski. >> reporter: for 72-year-old vietnam veteran, melvin morris, it was 44 years and coming. when president obama called with the news, morris collapsed to his knees. >> i was overwhelmed at that point. and he was saying, be cool, be cool, be cool. >> reporter: today at a highly emotional white house ceremony, president obama presented a medal of honor to 24 service members from world war ii, korea, and vietnam. all passed over at the time because they were hispanic, jewish or african-american. >> the ceremony is 70 years in the making. as one family member has said, this is long overdue. >> reporter: only three

including melvin morris are living today. one by one for more than an hour, each citation was read. >> knocking out the enemy mortar position and destroying both bunkers and killing their occupants. >> reporter: the president presented the highest military honor to the families of those who dedicated their lives to their country. as one of the original army green berets, staff sergeant melvin morris volunteered twice for vietnam. a battle in 1969 was almost his last. >> i went in and threw hand grenades everywhere. >> reporter: under relentless enemy fire, morris was gravely wounded, shot three times while retrieving the body of his team sergeant. that same year, specialist santiago ettevia was pinned down, the soldier next to him shot dead. surprisingly, morris doesn't believe he was the target of discrimination on or off the battlefield. >> it didn't matter, we all bled the same blood. >> reporter: the things morris cherishes most, his service and his green beret.

>> it's beat up, sewn up and survived. but i'll never wash it, because i always said, let the blood, sweat and tears stay in it. >> reporter: jim miklaszewski, nbc news, the pentagon. and still ahead for us tonight, our nbc news investigation, how general motors quietly changed the design of defective ignition switches but didn't alert drivers until it was too late. later, there are good reasons for it, we'll explain why, something with a funny name always happens to be one of the fastest growing physical activities in this country.

we're back as promised tonight with our nbc news investigation, the damage control continues for the nation's top carmaker. a day after apologizing for general motors mishandling as massive recall last month and announcing another one.

mary barra said she's creating a flew position of global safety director. much of this centers on how the company quietly changed the design of a flawed ignition switch. the decision that may have been the difference between life and death. nbc's gabe gutierrez has our report from detroit. >> our whole lives were changed in the blink of an eye. >> reporter: the night brooke melton died, her dad made a promise. >> i whispered, brooke, i will vindicate your accident, because i knew it was not her fault. >> reporter: the 29-year-old was driving her '05 cobalt when the black box data shows the ignition abruptly shut down. mark hood testified for the family in its suit against gm, which ultimately was settled for an undisclosed amount. he says the faulty ignition slipped out of run because of this critical part called a plunger. >> this is the spring loaded plunger that holds the switch in position. >> reporter: it fits into each slot, holding the ignition switch in run or accessory.

the problem is, hood says, this tiny part in recalled vehicle was too short, making it possible for the ignition to shift while driving. the air bags are disabled, the power steering is disabled and the power brakes are disabled. >> reporter: during the 2007 model year gm replaced the old part with this one, a longer plunger. the difference, 1.6 millimeters, the width of a quarter. >> the longer plunger and longer spring is more likely to stay in the run position. >> reporter: now, federal regulators are formally demanding answers. who at gm signed off on the change and why they weren't notified. >> gm had an obligation to notify nhtsa that there was a defect, and they had the obligation to recall the earlier models with the unsafe part. >> reporter: in video depositions obtained by nbc news, a gm design engineer responsible for the cobalt

ignition switch says he doesn't recall ever authorizing such a change. >> if any such change was made, it was made without your knowledge and authorization? >> that is correct. >> reporter: we couldn't reach him for comment, but we did stop by the home of another engineer who later headed up gm's internal investigation. >> reporter: mr. stoffer -- >> reporter: but he didn't want to talk to us. gm's new ceo mary barra declined an interview, but released this statement yesterday. >> something went wrong with our process in this instance and terrible things happened. >> reporter: four days before brooke melton's accident her father says the dealership in georgia told her there was no fix. that was in 2010, nine years after gm first noticed the problem, and four years after the company changed the ignition switch in new vehicles and in replacement parts. but brooke melton and her father didn't know. because gm didn't tell them or anyone else. right now there's a federal

criminal investigation underway, and congressional hearings are being planned for next month. today gm's ceo reiterated the company is cooperating fully with regulators, brian. >> gabe gutierrez reporting from detroit with us tonight. gabe, thanks. we're back in a moment with the sobering news out today of what awaits so many americans when work is over.

the world of fashion remains stunned by the death apparently by suicide of lauren scott. found dead in her new york apartment yesterday. the rolling stones today announced the postponement of their remaining tour dates in australia and new zealand. scott and mick jagger had been in a long term relationship. some grizzly news came out this week, pertaining to working americans, in the form of new polling stats, about what awaits them after a lifetime of work, 37% of american workers say they are somewhat confident about having a comfortable retirement, while 18% are now very

confident. here's the killer, 36% of american workers have less than $1,000 in savings and investments. so many are simply trying to live for the present day, buffeted by economic downturn and a changing u.s. economy. if you've been to disney world, you may remember the t-rex cafe, and if you know disney employees, you'll recognize their legendary calm in the face of adversity, as the aquarium fish tank in the center of the restaurant breaks. the water and fish flood in, the patrons, those who weren't stopping to take pictures, were ushered out swiftly. the employees used nets and trash bags to scoop up all the marine life they could. up next for us tonight, the new racquet in town happens to be one of the fastest growing physical activities in america.

finally tonight, if you're like me, the older you get, the better you were as an athlete back in the day. most folks still feel like they have a lot of fight left in them, even if they can't cover as much ground as quickly as back in the day. that may explain the rise of a sport growing in popularity. if you heard of pickleball or

you already play it, then you know. if you've never heard of something called pickleball, you're about to get a crash course in a fast growing activity from nbc's mark potter. >> reporter: if the pickleball craze has not yet hit your town, stand by, it's on its way. pickleball is one of the fastest growing sports in america, and can be played by just about anyone. including 91-year-old lee kritzer, vying for a medal at a pickleball tournament in del ray beach, florida. >> it gives you exercise. it's fun, social and competitive. >> reporter: although it's exploded recently, pickleball was invented almost 50 years ago near seattle. a combination of tennis, badminton and ping-pong. it's played with a paddle and a whiffle ball on a short court. this attracts older players who can still win without having to run too far. >> you can compete with the younger people by using your head. while they try to use their

speed. you out think them. >> reporter: watching this game being played, you might wonder why it's called pickleball. over the years it's been widely reported it's been named after the inventor's dog, pickle. the inventor's wife said the name actually came from a sport of rowing, where a pickle boat has a mixed crew. just like pickleball is a mix of other sports. the american pickleball capital may well be the villages, a huge retirement community near orlando. even with 140 pickleball courts, players form lines each morning to get a game. >> looking good. >> reporter: these women are passionate, much friendly competitors. >> every wednesday we start off with golf in the morning. >> then we go to lunch. and then we play pickleball. >> that's our triathlon. >> reporter: the usa pickleball association says the game is spreading around the world and easily has more than 150,000

players. a fun, fast moving sport with a funny name. mark potter, nbc news, orlando. that's our broadcast on a tuesday night. thank you for being here with us. i'm brian williams, and, of course, we hope to see you right back here tomorrow evening. good night. i seen a lot of red tape, and i seen policemen all over. >> that's whey neighbors say in this neighborhood, a deadly shooting. what they found inside the home that could have police solving multiple crimes. good evening. i'm jessica aguirre. >> i'm raj mathai. most neighbors had no idea what was happening inside the home. it's san jose's ninth homicide

of the year on epling lane. marianne favro has the latest. >> reporter: raj, a man was shot to death inside this home and a neighbor across the street tells me she heard several shots fired last night. we have also learned that homicide may not be the only crime committed here, sources tell us this was a marijuana grow house. tonight police are looking for the person who shot and killed the man inside this house on epling lane investigators have not released a name but said he was in his late 20s or early 30s. >> i was home all day. i didn't hear no gunshots or anything. >> reporter: she was surprised to learn she may have been living next door to a marijuana grow house. sources tell us there were pot plants growing in some bedrooms. a pg and e employee was called out to shut off the power after someone apparently manipulated