DHAKA: A US Navy ‘black box’ detector made its much-anticipated debut in the oceanic hunt for flight MH370 on Friday but Australia’s search chief warned it was crunch time with the box’s signal set to expire soon.

The Australian naval vessel Ocean Shield arrived with a ‘towed pinger locator’ capable of homing in on signals from the black box, as 14 planes scoured the remote Indian Ocean search area for signs of a crash site.

The plane disappeared on March 8, and Australian authorities coordinating the search have rushed the pinger device into place before the black box`s battery-powered location signal expires.

‘On best advice, the locator beacon will last about a month before it ceases its transmissions, so we`re now getting pretty close to the time when it might expire,’ said Angus Houston, head of a coordination centre directing the eight-nation search.

Houston said Ocean Shield, using the pinger locator, joined in an underwater search with the British navy’s hydrographic ship HMS Echo, which on Thursday began scanning for black box transmissions.

‘The Royal Australian Navy and Royal Navy have today commenced sub-surface search for emissions from the black box pinger from Malaysia Airlines flight MH370,’ he said, reports The Straits Times.

The Ocean Shield also bore an underwater drone vehicle ‘for mapping the seafloor’, authorities said.

Houston said planes and ships would continue looking for floating debris.

BDST: 1641 HRS, APR 05, 2014