The head of the Australian agency supervising the search for a missing Malaysia Airlines plane said today that an oil slick had been detected in the search area for flight MH370 in the Indian Ocean.
He also said that the autonomous underwater vehicle would soon be deployed, moving the search underwater after nearly six weeks of fruitless searching.
Houston added that although an oil slick was located in the search area on Sunday evening, he was pessimistic about the likelihood of finding any of the floating debris.
"I stress the source of the oil is yet to be determined but the oil slick is approximately 5,500m downwind... from the vicinity of the detections picked up by the towed-pinger locator on Ocean Shield," he said.
It would be a number of days before the oil could be conclusively tested ashore, but Houston said he did not think it was from a search vessel.
"The chances of any floating material being recovered have greatly diminished and it will be appropriate to confer with Australia's partners to decide the way ahead later this week," Houston said.
Searchers are confident they know the approximate position of wreckage of the Boeing 777-200ER (9M-MRO), some 1,550km northwest of Perth, and are moving ahead on the basis of four acoustic signals they believe are from its black box recorders.
"Despite the lack of further detections, the four signals previously acquired taken together constitute the most promising lead we have in the search for MH370," Houston told reporters in Perth.
"The experts have, therefore, determined that the Australian Ocean Shield will cease searching with a towed-pinger locator later today and deploy the autonomous underwater vehicle, 'Bluefin-21', as soon as possible," he said, referring to the United States navy device designed to detect the tell-tale "pings".
The US-made Bluefin-21, a 4.93m-long sonar device will now scour the seabed.
The sonar device, which weighs 750kg, can operate at a depth of up to 4,500m – roughly the depth of the ocean floor where the pings were detected.
Houston said that in the hunt for the plane's black box transmissions the last signal was logged six days ago.
"We haven't had a single detection in six days so I guess it's time to go underwater," he said.
The batteries in the plane's black box are now a week past their 30-day expected life and searchers will be relying on sonar and cameras on the Bluefiun-21 to detect the box.
Malaysia Airlines Flight MH370 disappeared soon after taking off on March 8 from Kuala Lumpur bound for Beijing with 227 passengers and 12 crew on board. – Agencies, April 14, 2014.