cover more ground this time. the navy says mission one covered only about four square miles. it was supposed to scan 15. after an abbreviated first launch, bluefin-21 is back in the water and searching, but so far no trace of flight 370. extremely deep water caused it to abort its first mission. one condition that causes it to abort its dive is if it reaches its maximum operating depth of 4,500 meters, so that s what happened in this case. bluefin can operate in water almost three miles deep, but turns out the search area was deeper than expected. bluefin was pushed to its limit. it should have spent two hours diving to the ocean floor, 16 hours searching for wreckage, and two hours resurfacing. instead, it only spent seven and a half hours in the water, including its trip to and from the surface.
it s maximum operating depth. that s what happened in this case. the charted sea floor depth that we have for this area is between 4200 and 4400 meters and 5 x 8 kilometer square or rectangle that it s searching. we hate deeper spot than we initially planned so we got to bring it up, reprogram it, shift it a little away from that deeper area and adjust our search pattern. the air chief marshal said the bluefin is being used in the most likely spot. i just was wondering about that. what makes that the most likely spot? is it in relation to the four sets of ping or other data? well, the information that tells us is the most likely location is the nature of the detection from the tow pinger locator we had in that area. it was the site of the highest signal strength or the loudest received signal. it was also where we had an increase in signal strength as
search was cut short. just six hours into its mission the bluefin-21 surfaced. 14 hours early. the bluefin was originally expected to scour the ocean floor for debris. the whole journey lasting 20 hours. but instead, the device resurfaced after the o official say it exceeded the operating depth of 14800 feet. we just hit a deeper spot than we initially planned so we just got to bring it up, reprogram it, shift a little bit away from the deeper area. and adjust our search pattern. meanwhile, a new detail emerging. a u.s. official tells cnn the co-pilot s cellphone was on during the flight and made contact with the malaysian cell tower. according to information shared by malaysian investigators. that cellphone signal reportedly detected about 30 minutes after the plane made that sharp westward turn, around the time the aircraft disappeared from
maximum operating depth of 4500 meters. that s what happened in this case. the charted depth is between 4200 to 4400 meters in that rectangle that it is searching. we hit a deeper spot that when initially planned. we have to bring it up, reprogram it, shift away from that deeper area and adjust the search pattern. the bluefin is being used in the most-likely spot. what makes that the most-likely spot? is there other data that is pointing to that particular location? the information that tells us is the nature of the detection from the towed pinger locator we had in that area. it was the site of the highest signal strength or the loudest received signal. it is also where we had an
sources close to the operation. they say the bluefin had been calibrated to go to a certain depth. it s not clear why but the vehicle started to move towards a lower depth and at that point it took itself out of the mission. a source close to the operation tells cnn, the bluefin-21 is back in the water, searching for possible debris in the same place it was looking monday night. the source says the underwater drone is operating at about the same depth as its first mission, even though in that first operation it overextended. the one condition that causes it to abort its dive is if it reaches its operating depth of 4500 meters. and that s what happened in this case. reporter: the bluefin was programmed to go a certain depth but it fell slightly below that level, down towards 2.8 miles below the surface. that s its maximum depth. it s unclear why it went so low but when it did, its safety mechanisms kicked in and brought itself up to the surface, 7 1/2