Urgent hunt for black box a race against a battery

Searchers for the missing Malaysia Airlines flight MH370 must gear up their hunt for the aircraft's black box, an aviation expert said as an Australian ship carrying equipment to locate the device set sail on Monday.

It is presumed that the black box will run out of battery power around April 7, or April 12 at the latest, and its signal will then vanish, said Wang Ya'nan, deputy editor-in-chief of Aerospace Knowledge magazine.

"I don't want to be pessimistic," Wang said, "but the fact is that without the signal, it will be virtually impossible to find it".