on the broadcast tonight, final moments. new questions about the timeline of events on board that missing plane. and new scrutiny on the pilots as we learn who likely uttered the final radio message from the cockpit. damage control. an iconic american company in crisis. tonight the woman in charge at gm speaks out about a deadly vehicle defect under investigation. where does it end?

riot police in the streets, part of ukraine now firmly in vladimir putin's control. president obama responds with sanctions. jolted awake. a big scare in southern california. the strongest earthquake to hit los angeles in years, renewing fears about the big one. "nightly news" begins now. good evening. i'm lester holt sitting in for brian who will be back tomorrow. it is without a doubt the most baffling aviation mystery of our time and it seems like everyone by now has a theory, a guess or opinion about what happened to malaysia airlines flight 370. after ten days the best investigators have been able to determine that is the disappearance of the jet was a deliberate act. and that it flew off somewhere into the northern or southern hemisphere. but the question of who is

behind it has tonight cast suspicion on the pilots. even as officials again today revised the timeline of this mystery. once again tonight tom costello leads off our expanded coverage. any signs of this search scaling back? >> a little bit. the pentagon telling us it is preparing to reduce the u.s. part of the search. the "uss kidd" will soon end search operations leaving only p-8 and p-3 aircraft to search massive areas of water. and with no other country finding any sign this plane was ever on radar, the search zone is shifting to the south. just 500 feet above the indian ocean a u.s. anti-submarine hunter today searching for any sign of flight 370. also today, more contradictions from malaysian authorities. after first saying the plane's last automated data or acars transmission was turned off before the last cockpit radio call, suggesting pilot involvement, today authorities backtracked. >> we don't know when the acars

system was switched off. all we know is the last transmission. and we did not receive a next transmission. >> reporter: here's the latest timeline. 12:41 a.m. saturday, march 8th, 370 left kuala lumpur bound for beijing. 1:07 a.m. it transmitted its last automatic data burst, called acars. the next acars transmission was scheduled for 30 minutes later. it never came. 1:19 a.m. the copilot radioed "all right, good night" as malaysian air traffic controllers handed the plane over to vietnamese controllers. just two minutes after the very standard conversation, 1:21 a.m., someone in the cockpit turned off the transponders that send speed, location, altitude and heading information. soon after that the plane turned around. at 2:15 a.m., the last radar contact in the strait of malaga, headed north. over the next six hours the plane transmitted one ping per hour to an orbiting satellite until 8:11 a.m. when the last ping was received. that puts it somewhere along these two arcs. as far north as kazakhstan.

as far south as the deep indian ocean. australia is now taking over that search zone. >> we will do our duty to the families of the 230 people on that aircraft who are still absolutely devastated. >> reporter: experts say turning off acars and the transponders, then flying the 777 for hours, requires expertise which is why there's intense focus on the cockpit crew. >> what is a potential motive, and what can be learned from looking deeply into the background of the pilot, the copilot, and anybody else on that plane that had the skill to fly it. >> reporter: meanwhile, for the family of american philip wood, the wait is agony. >> i don't believe that the plane has been crashed. i haven't ever believed the plane has been crashed. it just doesn't make sense to me. and i don't feel like that's the right answer. >> reporter: investigators continue to look at the backgrounds of everyone on board, including an off-duty flight engineer. but his father tells nbc news he was not a pilot, he was only a mechanic.

lester? >> all right, tom, thanks. while investigators say they're not ruling anyone out, they are taking a closer look at the captain and copilot of the plane. we'll get more on that tonight from nbc's kir simons in kuala lumpur. >> reporter: video on youtube, unverified, appearing to show the pilot and copilot passing through security. the pilot, zaharie shah, was known to love flying. he posted pictures on facebook with toy planes and helicopters. he had a flight simulator at home. that flight simulator is now in the hands of the police. they searched the pilot's home this weekend. it also emerged that the pilot had been active in malaysia's political opposition, but friends say that would not have motivated him to hijack his own plane. can you imagine him ever commandeering his own plane, putting his own passengers at risk? >> i cannot for one minute imagine him making that sort of decision.

>> it just wouldn't make any sense that he would have anything to do with any sort of deliberate action on his part. >> reporter: officials say captain zaharie and his copilot fariq hamid had not requested to fly together. and they are investigating everyone aboard flight 370. but the copilot's house was also searched. detectives were seen leaving with two of his relatives. the copilot could not have been involved, says the leader of his local mosque. >> because for me he's very good people. very humble, very innocent, respectable. >> reporter: it was the copilot, officials say, who was the last to speak to the control tower before the plane, and everyone on board, disappeared. kir simmons, nbc news, malaysia. >> again tonight we turn to an aviation expert, a former senior air safety director with the national transportation safety board and a veteran pilot. greg, always nice to have you here. >> thank you.

>> there's no search area. there's an arc over a lot of land mass on this planet. you've got investigators right now who are used to combing through wreckage. nothing to comb through. this is a difficult question because people are waiting for loved ones right now, but are there going to have to be some hard decisions made in this -- in the coming days and weeks? >> absolutely, lester. there comes a point where you have to really examine the return on investment. there are so many assets out there, so many countries that are participating, this stage of 11 days into this event if you will. because we're not really sure what kind of investigation to call it. accident or intentional act. i think the malaysians have said intentional act. so you have all these technical investigators sitting there waiting to do something. but they can't. there's going to come a point with this search area, so massive, that somebody's going to make a hard decision that they've done what they could with what they've had, and now we're going to have to find a point of calling it off and

moving on. >> which is why hopefully detective work will come up with something in the meantime. >> absolutely. that's going to be the key to this. because it is an intentional act according to the malaysians. >> all right, so painful. thank you very much, appreciate it. much more on our website, including what experts say about the remote possibility this plane could have actually landed somewhere. that's at nbcnews.com. general motors today announced a new round of recalls at the nation's largest automaker dealing with investigations on multiple fronts. tonight gm's new ceo is in full damage control mode. nbc's gabe gutierrez is in detroit. >> reporter: more than 1.5 million suvs, vans and cadillacs are part of gm's second wide-ranging recall this year. >> this announcement underscores the focus we're putting on safety and peace of mind of our customers. >> reporter: today, gm's ceo, on the job just two months, made her first video statement. since the carmaker announced its first recall, 1.6 million other cars, last month. for an ignition problem linked to at least 12 deaths.

>> as a member of the gm family and as a mom with a family of my own, this really hits home for me. we have apologized but that is just one step in the journey to resolve this. >> reporter: this new round of recalls is not related to the ignition switch. the models include buick enclaves, gmc acadias, chevy traverses, saturn outlooks all being recalled for defective side air bags. >> this is a departure for general motors compared to the company we saw 10 or 15 years ago. mary barra has made it clear she wants to be as transparent as possible. >> reporter: also on the recall list, newer cadillac xtss for concerns a brake engine pump could lead to an engine fire. chevy expresses and gmc savannahs, because gm says they don't meet head impact requirements. for some, convalescence in one of america's top brands is shaken. >> why spend the money if i'm not going to get the quality back? >> reporter: some analysts say the company will weather the

storm. >> i think if you look at other companies out there that have had serious recalls over the past few decades they've come back. >> reporter: but first, gm will have to face a separate criminal investigation and congressional hearings next month. there are no reported deaths or injuries related to this latest round of recalls. meanwhile, gm says it is expecting to take a $300 million hit in the first quarter because of all this. lester? >> gabe gutierrez in detroit, thank you. now to the crisis in ukraine. tonight russian flags are flying in the crimean peninsula following a controversial vote over the weekend. despite a wave of sanctions from the white house and european union today, many are wondering just how far russia might go. we'll hear from richard angle in crimea in just a moment. first we're joined by our chief foreign affairs correspondent andrea mitchell in our washington news room. andrea, good evening. >> good evening, lester. vladimir putin was defiant tonight. signing the decree recognizing crimea's independence, ignoring economic sanctions today from

the u.s. and europe. the russian president still strutting in the afterglow of the sochi games today awarding medals to the russian pair olympians, seemingly unfazed by u.s. sanctions. as crimeans celebrated, u.s. officials tacitly acknowledged crimea is lost. so is a ukrainian natural gas plant nearby, taken over by russia in a helicopter assault this weekend. the white house's new red line, any russian move into the rest of eastern ukraine. like donetsk, where pro-russian demonstrators were out in force. >> further provocations will achieve nothing except to further isolate russia. and diminish its place in the world. >> reporter: today the president froze american bank accounts and xherls with 11 top russian officials, crimean separatists, and ukrainian sympathizers. including former president yanukovych. if russia moves into eastern ukraine the president approved tougher measures against russian arms industry and oligarchs. putin's inner circle. >> we have tools available to us

to really ratchet up the economic and financial cost on russia if we choose to do so. >> reporter: on russia's state tv, defiance. against a mushroom cloud, the anchor said "russia is the only country in the world that is really able to turn the usa into radioactive ashes." >> he works for the kremlin, there's no doubt about it. and i think it's important that the world now sees what has been on russian television for years. >> reporter: and critics say putin won't respond to economic pressure, no matter how close it hits to home. andrea mitchell, nbc news, washington. this is richard angle in crimea where today they welcomed their new patron, russia. ♪ >> reporter: those old enough to remember the soviet union celebrated the reunion with moscow. but the party here was decidedly one-sided. riot police out in force to make sure anyone opposed to moscow remained silent. there's no doubt the majority of people here are happy to join with putin's russia.

but for the minority that doesn't want to, life just got a lot harder and maybe dangerous. hello. >> hello. >> nice to meet you. >> reporter: at a theater popular with activists, the director galina told us pro-russian thugs threw stun grenades into the crowded theater three times. "they were attacking intellectuals, it's madness. many of my friends want to leave." 25-year-old diliara is packing tonight. three small suitcases. that's all she can carry with her. you're just going to close the door, lock it behind you, and go? >> yes. >> reporter: she's worried crimea under russia is becoming a police state. >> i'm not here to live like this. >> reporter: she fears crimea has voted away its freedom. richard angle, nbc news, crimea. still ahead tonight, fearing the big one. a scare in southern california. news anchors duck for cover

during the strongest earthquake to hit l.a. in years. later, the shocking death of one of the top fashion designers in america, mick jagger's long-time companion found dead.

c'mon, you want heartburn? when your favorite food starts a fight, fight back fast, with tums. heartburn relief that neutralizes acid on contact. and goes to work in seconds. ♪ tum, tum tum tum... tums! mayo? corn dogs? you are so outta here! aah! [ female announcer ] the complete balanced nutrition of great-tasting ensure. 24 vitamins and minerals, antioxidants, and 9 grams of protein. [ bottle ] ensure®. nutrition in charge™. and you'll see just how much it has to offer, especially if you're thinking of moving an old 401(k) to a fidelity ira. it gives you a wide range of investment options... and the free help you need to make sure your investments fit your goals --

and what you're really investing for. tap into the full power of your fidelity green line. call today and we'll make it easy to move that old 401(k) to a fidelity rollover ira. the nation's capital and other parts of the mid-atlantic are cleaning up from another dose of winter. in washington more than half a foot of snow has fallen over the past 24 hours. it's one of the biggest late-season storms in that city's history. government workers as well as schoolkids got the day off. back now with that big scare before dawn this morning in southern california. a magnitude 4.4 earthquake shook millions of people awake in los angeles. the strongest quake to hit l.a. in years, renewing fears about when the big one will hit. nbc's miguel almaguer has our report. >> reporter: at 6:25 a.m., the violent jolt shook shelves and rattled nerves.

>> it was pretty scary. i was frightened. in fact, i was shaking. >> reporter: at convenience stores not far from the epicenter in encino, a scramble to safety. >> i think this one just like rattled me because it woke me up. >> whoa! >> earthquake. >> big earthquake right now. >> reporter: the 4.4 earthquake struck during the morning rush. >> thank you, coming up more problems for a -- >> earthquake. we're having an earthquake. >> reporter: many feared this could be the big one. >> it appears to have stopped. we're going to -- >> reporter: millions felt the shaking up to 40 miles away. there was no significant damage. at cal tech, the earthquake early warning system, a work in progress, was triggered 2 seconds before the tremblor. >> this earthquake was the biggest that we've had in the l.a. area in five years. >> reporter: dr. lucy jones, a seismologist with the u.s. geological survey, says this is a wakeup call. >> we'd really like to use this as a time to remind people, you decided you wanted to live in l.a., that means living with ea