CRI听力:Robotic Submarine to Search for MH370

After more than a month of searching for flight MH370, search crews will for the first time deploy a remote underwater vehicle to scour the seabed for wreckage from the plane.

The U.S. navy sub Bluefin-21 will be sent four and a half kilometers beneath the surface, sending back a three-dimensional map of the ocean floor.

Angus Houston is the head of the multinational search team.

"The deployment of the Autonomous Underwater Vehicle has the potential to take us a further step towards visual identification since it offers a possible opportunity to detect debris from the aircraft on the ocean floor."

Over the past 10 days, a pinger locator has picked up four separate signals.

Officials say one of the four signals is very strong and similar to the transmission from an emergency locator beacon.

No new signals have been picked up since Tuesday, suggesting the flight recorders' batteries have finally expired.

US Navy Captain Mark Matthews says the crew has identified priority locations for the sub to search.

"Based upon our broad searching with the Towed Pinger Locator, also based upon some of the returns that were achieved by the sonar buoys that were dropped, we've identified some areas that we priorities to go evaluate with the site scan sonar search. So our mission right now is to go look at the higher priority areas and to see if there are any debris there."

The sub will take 24 hours to complete each mission including two hours to dive to the bottom of the ocean and 16 hours to search the seafloor.

In its first deployment, it will search a 40-square-kilometer section of seafloor.

Officials have warned that the search could be a long painstaking process, and there's a chance the plane may not be found.

Meanwhile, visual searching for the missing plane continued on Monday with 12 aircraft and 15 ships scouring the ocean surface.

On Sunday, an oil slick was detected by an Australian navy vessel and a sample is now under analysis.

Houston, the head of the search team, says since the value of the visual search is diminishing, the operation may end in the next two to three days.

"We have reached a stage in the visual search where further efforts appear to be unlikely to yield results. So what is normal in these circumstances is the partners, the countries, get together, consult and decide what needs to be done next. And I think that consultation will take place later this week."

Flight MH370 was carrying 239 people including 154 Chinese when it disappeared in early March en route from Kuala Lumpur to Beijing.

Locating the flight's black boxes can help to understand what happened during the flight.

For CRI, I'm Yu Yang.