the plane , the coordination agency said it was " getting pretty close to the time when it might expire . "
but australia 's search chief said it was a race against time as the battery - powered signal fades after 30 days .
perth ( reuters ) - the search for missing malaysia airlines flight mh370 in remote seas off australia headed underwater on friday , with a u.s. navy high tech " black box " locator deployed for the first time as the battery life of the cockpit data recorder dwindles .
the area of highest probability as to where the aircraft might have entered the water is the area where the underwater search will commence , " retired air chief marshal angus houston , the head of the australian agency coordinating the operation , told reporters in perth . "
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 .
on monday it will be 30 days since the jetliner lost communications and disappeared from civilian radar less than an hour into an overnight flight from kuala lumpur to beijing on march
media caption richard westcott reports on the use of a pinger locator to find a black box the hunt for missing malaysia airlines flight mh370 moved into a new phase on friday 's search activities .
the search is being co - ordinated from the city of perth in western australia .