The clock is ticking in the hunt for the missing Malaysia Airlines plane as the only equipment that can detect the so-called black box will have less than two weeks to locate the device that holds instrumental information on what happened to the 239 passengers and crew members on board.
Officials said yesterday that once the two-week window - by the most optimistic estimate, as the black-box battery might fall silent earlier - closes, the search will enter a much more difficult phase.
It will take years to trawl the ocean floor before the flight data recorder can be located.
The Towed Pinger Locator 25, a hi-tech underwater device supplied by the US Navy that can detect the sounds, or pings, emitted by black boxes, was being installed yesterday on the Australian naval ship ADV Ocean Shield and is expected to arrive in the search area on Thursday at the earliest.
Watch: What is a black box?
The Chinese vessel Haixun 01, which is already in the search area, is also equipped with a searching device, Xinhua has reported.
But as the search for MH370 enters a third week, it is hoped that the data recorder's battery will last longer than its 30-day shelf life.
Captain Mark Matthews, director of ocean engineering with the US Navy, put the most hopeful estimate of extended shelf life at a further 15 days.
"But every day past 30 days is lower and lower probability," Matthews said.
As the highly sensitive pinger locator can only detect signals from within one nautical mile and can only be towed at three knots, Commodore Peter Leavy of the Royal Australian Navy said the operation's focus now was to narrow down the search area, which sprawls across 319,000 square kilometres of the southern Indian Ocean.
And the only way to do so is for the multinational contingent of aircraft and vessels to find and recover a confirmed object from MH370.
Aircraft at the search area have identified possible debris since Australian authorities decided to move the search area by about 1,000 kilometres last week. Haixun 01 and HMAS Success have retrieved some objects. But it was only fishing equipment and flotsam and nothing has been confirmed to be related to MH370.
Yesterday, eight vessels and 10 planes combed the new search site. Matthews said the operation would be much more difficult if the black box could not be located in the next two weeks.
Equipment using sonar systems would then be deployed to conduct mapping of the sea floor, which would take much longer than the two years that was required to retrieve the Air France 447 flight data recorder.
But Leavy, who is co-ordinating the international search from Perth, was hesitant to confirm whether the Australian navy would still be involved by then.
"We haven't gotten that far to figure out the next step. It will be driven by the Australian Transport Safety Bureau - the navy may not be involved."
He added that the equipment required to map the sea floor and retrieve the black box were commercially available.
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