hauled up on top of the mountain on tuesday for a music video for rachel long. beautiful view. >> "nbc nightly news" is next. we will have more local news right here on nbc bay area at 6:00. see you then. on this sunday night, the final moments aboard the doomed jetliner. chilling reports of what the co-pilot did while the captain desperately tried to get back in the cockpit. hard landing, an air canada flight careened off the runway. the nose of thplane sheared off and dozens eninjured. power threat. an investigation into just how vulnerable our nation's power grid really is and how the threats against it could put millions in the dark. and tipping point. it's showing up everywhere. digital tipping. is it shaming you into paying up? this is "nbc nightly news" with lester holt.

stub substituteing tonight, carl quintanilla. good evening. we're learning more tonight about the co-pilot of the german jetliner that crashed tuesday killing 150 people. a new report may help explain how the pilot got locked out of the cockpit and begged to be let in as the plane descended. all of this as the families of the victims continue to mourn their losses. katie tur is in germany with the latest. katie, good evening. >> reporter: carl, the flight data recorder is still missing. there's a chilling report about the other black box, the cockpit voice recorder describeing exactlyily what it sounded like in that plane. it was a glider friends say lubitz first learned to fly. friends that flew with him say it was clear he had a love for the sky. what's not clear is why he would crash a plane carrying 149 others into the side

of a mountain. no answers but today the german tabloid reported a timeline of the last minutes from the cockpit voice recorder. the flight started normally with the captain apologizing for a delay. during the descent he mentioned to the co-pilot lubitz he didn't get a chance to use the bathroom. lubitz says he can take over at any time. a few minutes later, he's prepareing for dus dorfdus -- dusseldorf. lubitz says you can go now. the captain leaves. shortly after, lubitz is heard pushing his chair back. the door clicks shut. the captain begins banging on the door screaming, for god's sake, open the door. passengers scream in the background. alarm bells sound and the captain says open open the damn door. nbc news has not confirmed this account and authorities will

neither confirm nor deny it. this remains a mystery. was it personal crisis or depression or another medical issue? lub bits had seen doctors for problems with his vision according to multiple reports although it's unclear how severe. but as investigators try to sort it all out, this grieveing father says it hardly matters. >> if there was a motive or reason, we do not want to hear it. it's not relevant. what is relevant is that this should never happen again. my son and everyone on that plane should not be forgotten, ever. >> reporter: today, investigators confirm they have dna from half the victims. now they're going to match that up with dna they were able to get from family members. carl, still a ways to go before they're able to bury their dead. >> katie tur in germany. thanks so much. in canada, a harrowing experience early today for passengers on another a-320 flight that made a hard landing which injured

dozens on board. the air canada plane slid off the runway at halifax international airport. we get the latest tonight from gabe gutierrez. >> the air canada flight came down hard, its nose broken off, one wing badly damaged. >> we have a report of a plane crash. aircraft emergency. airplane down. the airbus a-320 was flying from toronto to halifax nova scotia carrying 133 passengers and five crew members. >> we hit once and then crashed. then we just skidded for a very long time. >> i hit my head and said it's over. no way we were going to survive that. >> authorities say the plane touched down short of the runway and skidded for 1100 feet before it came to a stop. >> this caused considerable damage to the aircraft, and the main landing gear came off at that point. >> passengers say the plane hit a power line. the airport temporarily lost electricity. it was snowing, but the airline has not determined what caused the hard landing. >> it was safe to fly

in this weather. the aircraft slid for a period of time. >> 25 were rushed to the hospital, many clutching blankets. all but one have been released. incredibly there were no serious injuries. >> everyone started running. people were running off into the snow banks. >> people were pouring out of the plane. >> there was sparks and smoke. we were worried about it. >> this is the second incident this month of a plane sliding off the runway during a snowstorm. everyoneals sure also survived these harrowing moments at the new york laguardia airport. tonight air canada says it's fully cooperating with the national transportation safety board to find out what went wrong. amid the worsening crisis in yemen, the arab leaders agreed to combined military force. the goal is to counter islamic extremism in the region. many think it's designed to send a message to washington. nbc's chief on for correspondent richard

has our report. >> reporter: the arab world, which for decades has relied on the u.s. military for its defense is going its own way. the breaking point was yemen where saudi arabia launched more air strikes against rebels who are pushing close to the saudi border. on "meet the press," it was discussed how far the saudi kingdom was willing to go. >> reporter: we would you send ground troops in? >> we haven't made the decision to send ground troops so far. we have a plan in motion. we're executing this plan. >> reporter: that plan also appears to be a proxy war with iran. the rebels in yemen are backed by iran and today at a summit, in egypt leaders announced the creation of a combined arab army of 40,000 troops and decided in principle to combine aaron ran military

force says ss egypt's president sissy. why now? arab nations no longer trust the u.s. administration to stand up to iran because the u.s. policy toward the country appears confused and contradictory. in iraq, u.s. is providing air support. for iranian backed militia militias. in switzerland, washington is negotiateing with iran. in syria, the u.s. is both supporting the fight against iran's ally, president assad while at the same time helping him fight isis. >> i and 100 other people warned the administration. look, you can have negotiations, even have a deal with iran. you have to fit that into a wider regional policy that will work not just for iran. and i'm not so sure we were heard. >> a major shift is underway in the middle east with arab states seeming to turn their backs on washington by forming their own

military alliance unsure which side the u.s. is really on, theirs or iran's. carl? >> richard engle, thanks so much. tens of thousands took to the streets in tunisia today in a show of solidarity against islamic militants. they were joined by several world leaders including the president of france and italy's prime minister. the march comes one day after security forces killed members of a group blamed for recent deadly attack on the bar doe museumdot museum. in another show of resilience, that museum reopened to the public. pope francis held palm sunday mass in st. peter's square today, ushering in east ear's holy week start. tens of thousands took part waving palm leaves and olive branches. the pope remembered those that died in the germanwings crash. and others died defend defending their faith. the talks on scaling back iran's nuclear program is going down to the wire with two days before the deadline for an initial agreement. each side says the

other needs to make tough choices. our chief foreign correspondent, andrea mitchell has the report from switzerland. >> reporter: it has been a grueling round of talks as six world powers led by john kerry tried to bridge the divide with iran. >> do you think there will be a deal by the deadline? >> good question. >> everyone knows the deadline is midnight tuesday unless kerry and iran's foreign minister agrees to extend it. >> it has to be a deal which puts the bomb beyond iran's reach. >> i'm not paid to be optimistic. >> i'm not paid enough to be optimistic. >> reporter: even if kerry produces a deal, congress may try to scuttle it when he gets home. >> let's wait and see if there's an agreement. i've got serious doubts. we've got a regime that has never quite kept their word about

anything. tomorrow the defense will begin presenting the case in the boston marathon bombings trial after the prosecution puts its final witnesses on the stand. now the question on everyone's mind, will dzhokhar tsarnaev testify in his own defense? our justice correspondent, pete williams, has more. >> reporter: hoping to avoid a death sentence during the penalty phase to come leading defense laur judewyer judy clark has so far looked past the question of guilt surprising the jury on opening day saying this about the bombing and her client, it was him. no defense questions after emotional testimony from victims such as rebecca gregory that lost a leg or bill richard that watched his 8-year-old son die on the street. jurors saw surveillance video of tsarnaev and his older brother walking toward the finish line and dzhokhar with a separate backpack leaving it before the second blast.

dzhokhar seen running away a few seconds later and calmly buying milk in a grocery store half an hour after that. prosecutors say with the fbi closing in three days later, the brothers killed mit officer shaun collier trying to get his gun and carjacked this suv. the brothers leaped out after the owner managed to leap out and ran to the gas station across the street fearing for his life. a police pursuit ended in watertown in a wild shootout with bullets whizzing into nearby houses. a bomb thrown by the brothers blew a container erer nearly through the door of parked car. jurors saw the boat where tsarnaev hid for hours in a boat scratching a message into the wood claiming he was retaliateing for u.s. military operations is in the muslim world. now the defense will tell its story, claim claiming that tsarnaev, 19 at the time was companyiedy edied by his domineering older brother tamerlan, and that he's the one that shot

and killed sean collier. legal experts doubt he'll take the stand. >> it shifts the focus for the jury. the jury is focusing solely on that guy. do we like him? believe him? do we think he's a terrorist or not? >> the defense case will probably last a few days so the jury will likely start deliberating late this week or early next. then the same jury will sit through a separate trial on the penalty. carl. >> pete williams in boston tonight, thanks very much. in new york, new yorkers have now recovered two bodies from the rubble of that gas explosion in the city's east village neighborhood thursday. officials are working to determine if they are the bodies of two men that remain unaccounted for after the blast. when "nightly news" conditiontinues on this sunday an attack on our nation's power grid could leave millions without power. we have an investigation into how vulnerable it really is. and later, a pioneer in the west wing, and she answers to the president.

for the president. now to an investigation into the security of this country's power grid and threats against it that could leave millions in dark. we take a look at what internal department records show how often it has come under cyber attack and what's being done about it. jacob rascon has more. >> it was the most significant power attack on our nation's

power grid. the station was attacked by sniper fire, 100 rifle rounds damaging 17 transformers. >> this event was clearly a game changer for pacific gas and electric and the industry, no doubt about it. >> reporter: two years and 15$15 million in repairs later, still no named suspects, no arrests. from terror to theft, physical attacks on our power grid happen every week. department of energy records obtained and analyzed by "usa today" show more than 300 incidents in the past four years. >> many were incidents of attempted copper theft or copper theft. others were sophisticated like the metcalf incident. >> reporter: and now a new threat. cyber attacks. >> any given there's thousands of attempts to probe and get into the network systems on the power grid. we have defenses to prevent that. >> reporter: te

department of homeland security tells nbc news it is a priority to "strengthen our critical infrastructure. includeing our electrical grid. >> reporter: pentagon & e is spend spending $100 million to increase the facilities protection. there's a concrete wall, beefed up security controls, and added surveillance cameras. >> here we are in front of the substation with a wide open gate. >> reporter: a three month investigation by a bay area station found gaps at other sub-station substations. without providing details, pg&e told us they're implementing other advanced detection and deterrent measures. no one lost power in the 2013 attack, but it was a wake-up call. >> i think the metcalfe incident was a significant turning point for us. that's the reality. >> reporter: last november, industry

regulators put in place a new physical security standard requiring all companies to identify critical facilities, analyze threats and vulnerabilities, and enact new plans. as threats evolve attacks are frequent and one successful attack is too many. jacob rascon, nbc news, san jose california. when we come back, are digital devices guilting you into leaving a bigger tip?

thrill seekers got a little more than they bargained for at new york's coney island today. the 88-year-old cyclone roller coaster got stuck on the first run of the season. passengers were forced to walk down the tracks from one of the highest points on the

ride. no injuries were reported. college basketball fans also taken for a wild ride this weekend. three teams have punch punched their tickets to the final four. louisville was slugged in overtime following michigan state 76-70. for the second year in a row, wisconsin badgers sent the arizona wildcats packing. undefeated kentucky narrowly escaped a major upset, beating no notre dame 68-66. by now you may have experienced you're paying for a taxi or cup of coffee and you're prompted to leave a tip by an electronic screen. it's technology supposed to make life easier. some are are raising the question are digital devices pressuring us to pay more? >> reporter: they're showing up everywhere, tipping calculate calculators, taking the mystery out of the math. >> that makes it easier. >> with convenience comes what some call guilt tipping. >> you feel pressure

to be more generous than if that wasn't there. >> reporter: especially since the acceptable range of tips has also expanded often starting at 20% and going to 30% and more. the square reader was one of the first to simplify payments giveing small business businesses a way to accept credit cards using a mobile device, and you could leave a tip. the idea caught on. shopkeep, apple pay, google wallet, and others jumped in. not just for small businesses anymore but big ones too. >> tipping is going to get easier. you may find yourself ending up tipping more than you used to. >> reporter: what do you think about digital tipping options that show up on the screen? >> i went back and forth. i normally use it though. >> reporter: chen troy higgins started using the square payment system at his barber shop in atlanta, he noticed customers choosing to tip more. >> they were reluctant before because it was cash based. i put increments 20%,

30%, 50%. most go with the middle. >> it makes me tip more because i'm not even sitting and doing math and writing the total out. >> reporter: some say digital tipping can benefit workers like waiters who largely depend on gratuity. >> i work in the tipping industry myself, so i'm aware how to tip and how important tips are. >> reporter: these day, tipping for service could also mean paying extra for convenience. nbc news, new york. up next, the president's 27-year-old gate keeper who's breaking down some barriers of her own.

with a look at a young woman who has a much closer view of the presidency than most. she's the new receptionist in the west wing. a role that has her greeting presidents and primary ministers, but her own story is powerful in its own way. here's nbc's peter alexander. >> reporter: every morning in the nation's capitol, leah kate-hernandez arrives for work in the white house. she is the new receptionist of the united states. if he's the potus, she's the rotus. that's her desk steps from the oval office. she's 27, connecticut native, and she's deaf. >> fantastic opportunity and also to show that deaf people can do anything. >> from world leaders to white house scarf scarfers -- >> you have a meeting this morning? >> i do.

>> reporter: any who has a meeting with the president or top advisors comes to leah's desk first. she's provided an interpreter who alerts her when the phone rings. >> good morning, this is the west wing lobby, how may i help you? >> reporter: she was born deaf. her mom is jewish, a social worker. her dad, he's mexican-american, put himself through college and earned a phd. a former white house intern leah worked for president obama's re-election campaign before being hired on the first lady's staff. she remembers the first time they met. >> she used sign language and signed to me. she said hi, my name is michelle. she spelled out michelle obama. it was so incredible. >> have you taught the president sign yet? >> i saw him in chicago. he already knew some sign at that time. he passed by, and i waved to him. he signed thank you to me. >> reporter: on this morning, we went into press secretary josh earnest. >> she represents us very well. she really does. >> reporter: when you look around here what do you think? >> it's a great responsibility to be here as a deaf person, and i feel very proud

of the opportunities that have been given to me. >> reporter: a pioneer at the white house. how do you say, hello, mr. president? >> hello mr. president. >> reporter: one more time. hello mr. -- >> mr. president. >> president. >> defined by accomplishments not her disability. peter alexander, nbc news, the white house. and that is nbc "nightly news" for this sunday. lester holt will be here tomorrow. i'm carl quintanilla reporting from new york. from all of us here at nbc news, good night.

good evening. i'm vickie nguyen. we are following break news. a major earthquake has triggered a tsunami warning. that a is in effect within 620 miles of the earthquake epicenter. new guinea and islands are most at risk. western hawaii islands could see effects from this quake. we'll have updates as they happen. let's bring in our meteorologist rob with