A US Navy official warned Sunday that finding the missing Malaysian jet may be impossible, as efforts to locate the plane intensified ahead of the expected failure of its black-box homing beacons. “It all depends on how effective we are at reducing that search area,” Capt. Mark Matthews told reporters at Australia’s Stirling Naval Base near Perth. “Right now, the search area is basically the size of the Indian Ocean, which would take an untenable amount of time to search.”