Search teams have begun using towed pinger locators to hunt for the black box of missing Malaysia Airlines flight MH370.
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Two ships with the locator capabilities will search a 240km (150 mile) underwater path, in the hope of recovering the plane's data recorder.
Up to 14 planes and nine ships will also search for MH370 on Friday.
It disappeared on 8 March en route from Kuala Lumpur to Beijing. It was carrying 239 people.
It is believed to have crashed in the southern Indian Ocean, although no confirmed debris has been found from the plane.
The search is being coordinated from the city of Perth in Western Australia.
'Highest probability'
Angus Houston, head of the Joint Agencies Coordination Centre (JACC) leading the search, said that two ships had "commenced the sub-surface search for emissions from [the] black box pinger".
Australia naval vessel Ocean Shield was using a towed pinger locator from the US Navy, while HMS Echo, which had similar capabilities, was also searching.
Source: BBC