on this sunday night, the final moments a board the doomed jetliner. chilling reports of what the co-pilot did while the captain tried to get back in the cockpit. hard landing. the nose of the plane sheered off and dozens injured. power threat. an investigation into just how vulnerable our nation's power grid really is and how the threat 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. instituting tonight is carl. good evening. we're learning more about the

co-pilot of the 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 back in. this as the families continue to mourn their losses. katie is in germany with the latest. good evening. >> reporter: carl the flight data recorder is still missing. there's a chilling report siting the other black box, describing exactly what it sounded like inside the plane during its final minutes. it was a glider that friends say an degrees lubitz first realized his dream of flight. this was by a german tv station that shows lubitz at the control. 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 the plane killing 149

others into the side of a mountain. no answers. today the german tabloid reported a time line of the last minutes from the cockpit voice recorder. it started normally with the captain apologizing for the delay. he mentions the co-pilot that he did not get the chance to use the restroom. lubitz tells the captain he can take over at niz time. the captain tells lubitz to prepare for landing at dusseldorf. a few minutes later, he says you can go now. lubitz is heard pushing hitz chair back the door clicks shut. the plane begins to descend. air traffic control calls. no answer. the captain starts banging on the door saying for god's sake open the door. passengers start streaming. the bells sound and the captain says open the door. as the search continues, lubitz

motive remains a mystery. was it a personal crisis depression or another medical issue? lubitz had seen doctors for problems about his vision according to multiple reports. it's unclear how severe. as investigators try to sort it out, this grieving father says it hardly matters. >> if there was a motive or reason we do not wanted to hear it. it's not relevant. what is relevant is this should never happen again. my song and everyone on that plane should not be forgotten, ever. >> reporter: today investigators confirm they have dna from half of the victims. 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. >> thanks so much. in canada a heroing experience for passengers on another flight that made a hard

landing that injured dozens on board. the plane slid off the runway at halifax international airport. we get the latest tonight from gabe gutierrez. >> reporter: it came down hard, nose broken off, one wing badly damaged. the air bus air 320 was flying from toronto to halifax. >> we hit once and crashed. we skidded for a long time. >> i hit my head. i said it's over. there's no way we're going to survive that. >> reporter: authorities say the plane touched down short of the runway and skidded 1100 feet before it came to a stop. >> this caused considerable damage to the aircraft and the mainlanding 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. 25 were rushed to the hospital many clutching blankets. all but one have been released. incredibly there were no serious injuries. >> people pouring out of the plane. >> we were worried about it. >> reporter: this is the second incident this month of a plane sliding off the run way during a snowstorm. everyone survived these heroing moments at new york's laguardia airport. air canada says it's fully cooperating with the air safety board to find out what went wrong. nbc news. amid the worsening crisis in yemen, arab leaders agreed to combine a military force. it will goelg is to counter extremism and iranian influence in the region. many think it's to send a

message to washington. richard angle has our record. >> the arab world which for decades relied on u.s. military for defense is going its own way. the breaking point was yemen where saudi arabia launched more air strikes against rebels pushing dangerously close to the saudi border. on ""meet the press"" the saudi ambassador discussed how far the saudi kingdom is ready to go. >> why would you send ground troops? >> we have not made the decision to send ground troops so far. it's an air campaign. we have a plan in motion. we're executing the plan. >> the plan seems to be a proxy war with iran. rebels are backed by iran. today at a summit in egypt, arab leaders announced the standing combined arab army of 40,000 troops. arab leaders have decided in principle to form an arab

military force says sissi. arab states no longer trust the u.s. administration to stands up to iran because the u.s. policy toward the country appears confused and contradictory. in iraq, u.s. is providing air support for backed militias. in switzerland, washington is negotiating with iran. in yemen u.s. advisors left the fight with backed militias. in syria, the u.s. is supporting the fight against iran's ally assad bile at the same time helping him fight isis is. >> his and 100 other people warned the administration. you can have negotiations and a deal with a ran, but you have to fit that into a wider regional policy that will work not just for iran. i'm not so sure we were heard. >> a major shift is underway in

the middle east with those turning they're backs on washington unsure which side the u.s. is really on theirs or irans. carl? >> richard, thanks so much. tens of thousands took to the streets 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 skurtz forces killed members of the group blamed for the deadly attack at the museum. in another show of resilience that museum opened to the pub like. the pope held a palm sunday mass. tens of thousands took part in the service waving palm and olive branches. he remembered those that died in the germanwings crash and paid tribute to those who died defending their faith. the talks of scaling back the nuclear program is going down to the wire with two days before the deadline for initial

agreement. each side says the other needs to make tough choices. andrea mitchell has our report from switzerland. >> reporter: it's been a round robin of talks as six world powers led by john kerry try to bridge the divide. everyone here knows the deadline is two days from now, midnight tuesday, unless kerry and iran es foreign minister agree to extend it. >> the deal does get done it has to be a deal that puts beyond iran's reach. >> even if kerry produces a deal, congress may try to scuttle it when he gets home. >> let's see if there's an agreement. i've got serious doubts. we've got the regime that's never kept their word about

anything. tomorrow the defense will begin presenting the case in the boston marathon bombings trial after the prosecution puts final witnesses on the stand. now the question on everyone's mind, will tsarnaev testify in his own defense? we have more. >> hoping to avoid a death sentence lead defense lawyer judy clark has looked past the question of guilt surprising the jury saying this about her clietn. it was him. emotional emotional victims gave their system. jurors saw surveillance video of tsarnaev and his older brother walking toward the finish line and sow dzhokhar coming with a backpack running away seconds

later and calmly buying milk at a grocery store half an hour after that. the brothers killed mit police officer shaun trying to get his gun and carjacked this suv. the driver managed to leap out when the drivers stopped for gas and pleaded for help at a gas station fearing for his life. a police pursuit ended in watertown in a wild shootout with bullets whizzing into nearby houses. jurors saw the bullet riddled boat where tsarnaev hid hours writing a message inside scratching it into the wood. now the defense will tell its story claiming that tsarnaev 19 at the time was a vulnerable adolescent coaxed by his older brother that shot and killed

collier. the he'll defenses doubt he'll take the stand. >> it shifts the focus for the jury. the jury is focussing solely on that guy. do we like him? believe him? think he's a terrorist or not? >> the defense case will probably last a few days so the jury will likely start deliberating early this week or next. then a separate jury will sit in on the trial. >> thanks very much. in new york emergency workers have recovered two bodies from the rubble from the gas explosion until east village neighborhood thursday. workers are working to determine if they are the bodies two men unaccounted for. when nightly news continues, the attack against the power grid could leave millions without power. we look there's nothing more romantic than a spontaneous moment. so why pause to take a pill?

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now to an investigation into if security of this country's power grid and threats against it that could leave millions of americans in the dark. in collaboration with u.s.a today, we look at what the energy records show about how often the grid has come under physical and cyber attack and what's being done about it. jacob rascon has more. >> it was the most significant attack ever on our nation's power grid the substation

powering part of silicon valley attacked by sniper fire 10 rifle rounds damaging 17 transformers. >> this event was clearly a game changer for gas and electric industry no doubt about it. >> we'res and $15,000 in repairs later no named suspects and no arrests. physical attacks on our power grid happen every week. department of energy records show more than 300 incident this is the past four years. >> many were simple incidents of attempted copper theft or coer theft. others were sophisticated attacks like metcaf. >> every given day there's thousands of attempts to probe and get into the networks and control systems on the power

grid. we have to prevent that. >> the department of homeland security tells nbc news it's a quote, strengthen the security and resilience of critical to the power grid. >> they're spending $100 million to increase protection at the facility. there's a concrete wall for beefed up control and added security cameras. a three month investigation by the bay area tv station found security gaps at other stations. without providing details, pg&e told us they're implementing other advanced measures. no one lost power in the 2013 attack but it was air wake-up call. >> the metcaf incident was a turning point for us. that's reality. >> last year a new physical

security standard was put in place allowing all to identify critical facilities analyze threats and vulnerabilities and enact new security plans. as threats evolve, threats are more frequent. one successful attack is too many. nbc news california. when we come back our digital devices guilting you into leaving a bigger tip? curling up in bed with a ... ...favorite book is nice. but i think women would rather curl up with their favorite man. but here's the thing: about half of men over 40 have some degree of erectile dysfunction. well, viagra helps guys with ed get and keep an erection. and remember, you only take it when you need it. ask your doctor if your heart is healthy enough for sex. do not take viagra if you take nitrates for chest pain; it may cause an unsafe drop in blood pressure side effects include headache, flushing, upset stomach and abnormal vision. to avoid long-term injury, seek immediate medical help

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highest points on the ride. no injuries reported. three teams have punched their tickets to the final four. louisville was slugged in overtime forling michigan state 76-70. for the second year in a row, wisconsin badgers sent the arizona wild cats packing. undefeated kentucky narrowly escaped a major upset beating notre dame. by now you may have experienced it you're pay ago for a taxi or cup of coffee and prompted to leave a tip by an electronic screen. it's technology supposed to make life easier. some are raising the question are digital devices pressuring us to pay more? >> they're showing up everywhere typical cue lay tors taking the mystery out of the math. >> it's the push of a button that makes it a lot easier. >> with convenience comes with some call guilt tipping.

>> you feel pressure to be more generous than you would if there wasn't weather. >> and the acceptable range of tips have expanded starting at 20% going to 30% and more. the square reader was one of the first ways to simplify payments using a mobile device. you could add a tip. the idea caught on. shop keep apple pay, google wallet and others jumped in. not just for small businesses anymore but big ones too. >> it's going to get easier. you may find yourself tipping more than you ought to. >> what do you think about the tipping on the screen is this. >> i usually use it though. >> when he started using the tipping system at his barbershop he noticed customers to tip more. >> they were reluctant to do it more because it was cashed base. i put increments where they need to be.

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we end tonight with a look at a young woman who has a much closer view of the presidency than most. she's the reception in the west wing. her own story is powerful in its own way. here's peter alexander. >> every morning in the nation's capital, leah arrives in the white house. she's the new receptionist. she's the rotus. that's her desk steps from the oval she's 27 connecticut native and she's death. >> fantastic opportunity to show deaf people can do anything. >> from world leaders to white house staffer, anyone who has an a appointment with the president or top advisors comes to leah's

desk first. she's provided with an interpreter. leah was born deaf part of a deaf family. her mom is jewish and her dad earned his way through college and phd. leah still remembers the first time she met. >> she used sign language and signed to me. she said hi my name is michelle and spelled out michelle obama. >> have you talked to the president in sign yet? >> i talked to him in chicago. he knew sign at that time. he passed by me. i waved at him. he signed immediately thank you to me. >> on this morning, we ran into josh earnest. when you look around here, what do you think? >> it is a great response bltd to be here as a deaf person. i feel very proud of the opportunities that have been

given to me. >> a pioneer at the white house. >> how do you say, hello mr. president? >> hello mr. president. >> one more time. >> hello mr. president. >> mr. president. >> defined by her 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 reporting from new york. from all of us here at nbc news, good night.

daly: last night the knockouts began. blake: this is where they really have to step up. i just want the best team i can possibly have. ♪ you and i collide ♪ daly: the best of the best faced off... gracious. ♪ you make me feel ♪ daly: ...for a spot in the live playoffs. ♪ like a natural woman ♪ whoo! daly: tonight, six more artists... hi. ...will hit the stage with songs they picked. what song you gonna be doing? "live like you were dying" by tim mcgraw. oh, man. "listen to your heart." "higher love," steve winwood. okay. this is a round where we get to see what they think of themselves as an artist. ♪ carry on ♪ daly: helping them all front man of the band fun. with over 20 million singles sold... ♪ may your past be the sound ♪ ...fresh off his solo hit "nothing without love"... ♪ of your feet upon the ground ♪ ...singer-songwriter nate ruess. there's a uniqueness that your voice has, but you have to chill out. yes. "the voice" is great because you get people who have been through