Bluefin submarine to resume search for MH370 within days

The Bluefin-21 Autonomous Underwater Vehicle is craned over the side of the Australian Defence Vessel Ocean Shield in the southern Indian Ocean during the continuing search for the missing Malaysian Airlines flight MH370 on April 17, 2014. -- FILE PH
The Bluefin-21 Autonomous Underwater Vehicle is craned over the side of the Australian Defence Vessel Ocean Shield in the southern Indian Ocean during the continuing search for the missing Malaysian Airlines flight MH370 on April 17, 2014. -- FILE PHOTO: REUTERS

PERTH (AFP) - A mini-sub hunting for missing Malaysia Airlines Flight MH370 will be back in the search zone within days, an official said on Saturday, as the Australian ship carrying the device prepared to leave on the mission.

Australian vessel Ocean Shield is carrying the US Navy Bluefin-21 mini-sub which had been scouring the seabed for the plane until it docked to resupply early this week.

Ocean Shield is due to head back on Saturday to the remote area of the Indian Ocean where transmissions believed to have come from the plane's black box recorders were heard last month. It will take the vessel three days to reach the location.

Once in the area, Ocean Shield will be able to deploy the Bluefin-21 to look for "any non-normal items, any metallic items", US Navy Captain Mark Matthews told the Australian Broadcasting Corporation. "They'll either find something or they won't, that's about all I can box in, but what you do is you go look at your best indications and you pursue them until they're exhausted," he said.

Captain Matthews said it was impossible to know for sure whether the signals picked up were from the plane's black box. "It is certainly a man-made signal, but what it's from, I can't look at it and positively say, 'Hey that's an underwater locator beacon'," he said.

Flight MH370, carrying 239 people, disappeared on March 8 while travelling from Kuala Lumpur to Beijing. Extensive air and sea searches over vast stretches of the Indian Ocean have failed to find any sign of the plane.

Australia, which is leading the search, has stressed that it believes it is looking in the right area based on satellite communications from the plane. Officials have scaled back the air and sea searches, and have said that an intensified undersea mission will begin once new, more sophisticated equipment can be obtained to search at depths of more than 4,500 metres.

The ocean bed in the prospective search zone is several kilometres deep and largely unmapped, meaning specialist sonar equipment and other autonomous vehicles are needed. Until these can be deployed, the Bluefin-21 will continue the search while oceanographic work will also be done.

Meanwhile international experts are re-examining satellite imagery and all the data collated so far to try to pinpoint a more precise location for the search.