PERTH - Australian navy vessel Ocean Shield, which has been searching for Malaysia Airlines flight MH370 with a towed pinger locator, will deploy the autonomous underwater vehicle Bluefin-21 later on Monday.
"The black box batteries will certainly almost be totally expired. It's time to go underwater,'' Mr Angus Houston, head of Australia's Joint Agency Coordination Centre (JACC), told a press briefing on Monday.
“Ocean Shield will cease searching with the towed pinger locator later today and deploy the autonomous underwater vehicle Bluefin-21 as soon as possible,” he said.
The US-made Bluefin-21, a sonar device, will search an area of about 40 sq km and can go as deep as 4,500m, roughly the depth of the ocean floor where the pings were detected, he added.
His comments came as the search for the plane entered the 38th day on Monday. The batteries of the black box have an advertised shelf life of 30 days.
"There have been no confirmed signal detections since last Tuesday night,'' said Mr Houston, adding that it's possibly because the batteries had run out.
He also told reporters that Ocean Shield detected oil slick on Sunday but the source has yet to be determined.
"The oil slick is approximately 5,500 metres downwind... from the vicinity of the detections picked up by the towed pinger locator on Ocean Shield,” he said, adding that it would take several days for the oil to be conclusively tested.
"We have to be realistic'' about the search, he said, adding that "this is one of the largest search operations of my lifetime".
MH370 disappeared soon after taking off on March 8 from Kuala Lumpur for Beijing with 227 passengers and 12 crew on board, triggering a multinational search that is now focused on the Indian Ocean.
Search aircraft and vessels have been scouring an area north-west of Perth, after picking up four acoustic signals that they believe are from the plane's black box recorders.
Up to 12 aircraft and 15 ships are involved in Monday's search for missing plane, said JACC.