Nightly News | March 14, 2014
>>> 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, flying far from where it was supposed to be and vanishing without a trace. tonight there is evidence that it made not one but two changes of course after it appeared to leave the radar screen. that has dramatically shifted the search efforts, while at the same time expanding the possibilities of where the plane ended up. so much of this flight has not added up. but what does tonight, the investigators are looking into the possibility that somebody deliberately flew the plane into danger. nbc's tom costello has more. what is the data telling them about the plane?
>> reporter: investigators believe it headed south over the indian ocean . to do that they're tracing the electronic ping on the satellite, similar to a cell phone pinging to a tower even when you're not communicating. but the search zone could be thousands of miles, not hundreds. more than six days since the boeing triple 7 went missing, the malaysian authorities laid out some possibilities.
>> it could be done intentionally, it could be done under duress, it could be done because of an explosion, i don't want to go into the realm of speculation.
>> reporter: here is what they have, the radar path showed it made a deliberate u-turn and headed west over the strait of malacca. the pings, the plane did continue to send pings once an hour to an orbiting satellite. they say that the routine automated pinks were registered during the flight from kuala lumpur , now the investigators are using the pings to determine where the plane went for five hours.
>> hopefully with more work on the data and refinement, if you will, they can get more data on where the plane went.
>> reporter: now it stretches from the strait to bengal, where the u.s. navy is searching. the plane loaded with under water search technology should start to work tomorrow. we talked to commander william marks .
>> there is no way you can search the entire indian ocean . it is an amazing platform, it can't be done with ships alone. and even our p 3 and pe with the range of a thousand or so miles they will have to return.
>> reporter: if they ever find the wreckage, the black boxes will be critical to find out what happened. the fdr will tell them data.
>> the flight data recorder will tell us hundreds of thousands of data, what the plane did.
>> reporter: but the cockpit voice recorder only tells 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 that, as well.