A Submarine Has Taken Over the Missing-Jet Hunt

The hunt for missing Malaysia Airlines Flight 370 moved underwater Monday, as investigators halted the use of towed pinger locators to find the doomed Boeing 777’s black boxes, and instead deployed an unmanned submarine in a bid to find wreckage on the ocean floor far off Australia’s west coast.

“We haven’t had a single detection in six days so I guess it’s time to go underwater,” Angus Houston, who is in charge of joint search efforts, told reporters in Perth. “I emphasize this will be a slow and painstaking process.”

MH370 vanished soon after taking off from Kuala Lumpur bound for Beijing early March 8, and subsequent data transmissions indicate it may have crashed in the southern Indian Ocean with all 239 passengers and crew members presumed lost.

Four pings, possibly from the 11-year-old jetliner’s flight recorders, have been detected in a 10-by-24-km (6 by 15 miles) triangle some 1,500 km (950 miles) northwest of Perth. But the devices’ batteries only have a typical life span of 30 days, and as Monday marked Day 38 since the plane disappeared, investigators believe it is now futile to hope for additional signals.

From Monday evening, a Bluefin-21 unmanned underwater vehicle will snake backward and forward on the ocean floor using side-scan sonar to search for wreckage. The submarine will operate on a 24-hour continuous cycle — taking two hours to reach the ocean floor, 16 hours to comb 40 sq km (15 sq. mi.), two hours to return to the surface and then four hours to download and analyze collected data.

Waters are believed to be around 4.5 km (2.8 miles) deep at the search zone, putting them at the limit of Bluefin-21’s operating capacity. Nevertheless, the submarine, operated from the Australian navy vessel Ocean Shield, is the only such asset currently available and, said Houston, “more than adequate to the task.”

“Most of the search area is on the right side of 4,500 m for the operation of the vehicle,” he said. “There are vehicles that can go a lot deeper than that. Those sorts of possibilities are being looked at as we speak.”

Although the ocean floor where Bluefin-21 is operating was described as rolling rather than mountainous, it is apparently covered with a thick layer of silt, which may complicate search efforts. The British navy’s H.M.S. Echo is currently providing high-tech oceanographic assistance to Ocean Shield in the vicinity. “This is an area which is new,” Houston said.

Up to 11 military aircraft, one civil aircraft and 15 ships helped search some 48,000 sq km (18,500 sq. mi.) of ocean — around twice the size of Vermont — on Monday for floating debris from MH370. But the air and surface operation, which is already the most expensive in aviation history, will be wrapped up in the next three days, near where the aircraft is presumed to have entered the water.

“The chances of any floating material being recovered have greatly diminished, and it would be appropriate to consult with Australia’s partners to decide the way ahead later this week,” said Houston.

On Sunday evening, an oil slick was discovered by Ocean Shield around 5.5 km (3.5 miles) downwind from the pinger-locator detections. A sample will be analyzed for traces of jet fuel once it can be taken ashore, but this may take several days.

“I would not term it a long shot,” said Houston. “I would determine it as a promising lead that needs to be [investigated] until we can either confirm or discount.”