- Malaysia Airlines MH370 plane: Malaysia has to upgrade defence after parting with radar dataMalaysia Airlines Flight MH370 search area too deep for 'Bluefin 21' submarineMalaysia Airlines Flight MH370 search area too deep for submarineUndersea drone hunt for Malaysia Airlines Flight MH370 may take two months
A robotic submarine hunting for the missing Malaysia Airlines MH370 jet aborted its first mission after only six hours, surfacing with no new clues when it exceeded its maximum depth along the floor of the Indian Ocean, officials said Tuesday.
Search crews sent the U.S. Navy's Bluefin 21 into the depths Monday to begin scouring the seabed for the missing Malaysia Airlines Boeing 777 after failing for six days to detect any new signals believed to be coming from its black boxes.
But the 16-hour mission was cut short when the unmanned sub, which is programmed to hover 30 meters (100 feet) above the seabed, entered a patch that was deeper than its maximum depth of 4,500 meters (15,000 feet), the search coordination center and the U.S. Navy said.
A built-in safety feature returned the Bluefin to the surface and it was not damaged, they said.
The data collected by the sub was later analyzed and no sign of the missing plane was found, the U.S. Navy said. Crews were shifting the Bluefin's search area away from the deepest water and were hoping to send it back on another mission later Tuesday.
Search authorities had known the primary search area for Malaysia Airlines MH370 was near the limit of the Bluefin's dive capabilities. Deeper-diving submersibles have been evaluated, but none is yet available to help.
A safety margin would have been included in the Bluefin's program to protect the device from harm if it went a bit deeper than its 4,500-meter limit, said Stefan Williams, a professor of marine robotics at the University of Sydney.
"Maybe some areas where they are doing the survey are a little bit deeper than they are expecting,'' he said. "They may not have very reliable prior data for the area.''
Meanwhile, officials were investigating an oil slick about 5,500 meters (3.4 miles) from the area where the last underwater sounds were detected.
Crews collected an oil sample and sent it back to Perth in western Australia for analysis, a process that will take several days, said Angus Houston, the head of the joint agency coordinating the search off Australia's west coast.
He said it does not appear to be from any of the ships in the area, but cautioned against jumping to conclusions about its source.
The Bluefin can create a three-dimensional sonar map of any debris on the ocean floor. But the search is more challenging in this area because the seabed