PERTH, Australia - The search area for the missing Malaysian jet has proved too deep for a robotic submarine that was hauled back to the surface of the Indian Ocean less than halfway through its first seabed hunt for wreckage and the all-important black boxes, authorities said today.
Meanwhile, officials were investigating an oil slick about 3.4 miles from the area where the last underwater sounds were detected, said Angus Houston, the head of a joint agency coordinating the search off Australia’s west coast.
Crews have collected an oil sample and are sending it back to Australia for analysis, a process that will take several days. Houston said it does not appear to be from any of the ships in the area but cautioned against jumping to conclusions about its source.
Search crews sent the Bluefin 21, launched from the Australian navy ship Ocean Shield, deep into the Indian Ocean on Monday to begin scouring the seabed for the missing Malaysia Airlines Boeing 777 after failing for six days to detect any more signals believed to be from its black boxes.
But after only six hours of its planned 16-hour mission on the seabed, the autonomous underwater vehicle exceeded its maximum depth limit of 14,762 feet, and its built-in safety feature returned it to the surface, the search coordination center said in a statement today.
What if anything it might have discovered during the six-hour search was still being analyzed, it added.
The Bluefin 21 will resume the search today when weather conditions permit, it said.
Search authorities knew that the primary wreckage from Flight MH370 was likely lying at the limit of the Bluefin’s dive capabilities. Deeper diving submersibles have been evaluated, but none is yet available in the search area.
The move comes after crews picked up a series of underwater sounds over the past two weeks that were consistent with signals from an aircraft’s black boxes, which record flight data and cockpit conversations. The devices emit “pings” so they can be found more easily, but their batteries last about a month.
“Today is day 38 of the search,” Houston told a news conference. “We haven’t had a single detection in six days, so I guess it’s time to go underwater.”
Australian Prime Minister Tony Abbott raised hopes last week when he said authorities were “very confident” the four strong underwater signals that were detected were from the black boxes on Flight 370, which disappeared March 8 during a flight from Kuala Lumpur, Malaysia, to Beijing with 239 people on board.
But Houston warned that while the signals are a promising lead, the public needs to be realistic about the challenges facing search crews in the remote, deep patch of ocean - an area he called “new to man.”
“I would caution you against raising hopes that the deployment of the autonomous underwater vehicle will result in the detection of the aircraft wreckage. It may not,” Houston said. “However, this is the best lead we have, and it must be pursued vigorously. Again, I emphasize that this will be a slow and painstaking process.”
The Ocean Shield had been dragging a U.S. Navy device called a towed pinger locator through the water to listen for any sounds from the black boxes.
The Bluefin sub takes six times longer to cover the same area as the ping locator, and the two devices can’t be used at the same time. Crews had been hoping to detect additional signals before sending down the sub so they could triangulate the source and zero in on the location of the black boxes.
The submarine will take 24 hours to complete each mission: two hours to dive to the bottom, 16 hours to search the seafloor, two hours to return to the surface and four hours to download the data, Houston said. In its first deployment, it will search a 15-square-mile section of seafloor.
A visual search for debris on the ocean surface continued Monday over 18,400 square miles of water about 1,400 miles northwest of the west coast city of Perth. A total of 12 airplanes and 15 ships joined the search.
But Houston said the visual search operation will end in the next two to three days. Officials haven’t found a single piece of debris confirmed to be from the plane, and he said the chances that any would be found have “greatly diminished.”
“We’ve got no visual objects,” he said. “The only thing we have left at this stage is the four transmissions and an oilslick in the same vicinity, so we will investigate those to their conclusion.”
Up to 11 planes and as many ships were to join today’s search over 24,000 square miles, 1,400 miles northwest of Perth.
Information for this article was contributed by Kristen Gelineau and Rod McGuirk of The Associated Press.
Front Section, Pages 8 on 04/15/2014