TODAY | April 18, 2014
>>> the search for malaysia air flight 370. the unmanned bluefin-21 submarine has now scanned 42 square miles of the indian ocean floor, but so far, no signs of debris and it's back in the water this morning. nbc's katy tur is in perth, australia. katy , good morning.
>> reporter: good morning, carson. five days into bluefin-21's deployment and they're all but ironing out the kinks. after two aborted missions, it was able to complete two successful dives. two full 16-hour passes of the ocean floor . it is right now doing its fifth dive as we speak. so far, nothing to report from those scans, but searchers say they are confident that they'll be able to find it as they've been able to narrow down the search zone significantly by further refining those four sets of acoustic signals that ocean shield heard last week. now, that is good news, because it's unclear how much longer the countries involved will be able to keep footing the bill for this. one estimate puts the search total at about $234 million when all is said and done, and while officials here have said recently that it shouldn't take two months for this search to finish, it is still a slow and arduous process. as you said, bluefin-21 has only been able to map about 42 square miles so far. carson?
>> all right, katy tur in perth, australia. thanks so much.