Flight 370: Search Crews Fail to Relocate Black Box ‘Pings’ Detected Earlier

Malaysia Airlines Flight 370: No new "black box"-like sounds heard (CBS News)

PERTH, Australia -- Search crews hunting for the missing Malaysia Airlines jethave failed to relocate faint sounds heard deep below the southern Indian Ocean that officials said were consistent with a plane's black boxes, the head of the search operation said Tuesday.

Angus Houston, the retired Australian air chief marshal who is heading the search far off Australia's west coast, said sound locating equipment on board the Ocean Shield has picked up no trace of the signals since they were first heard late Saturday and early Sunday.

Time may have already run out to find the devices, whose locator beacons have a battery life of about a month. Tuesday marks one month since the plane vanished. Once the beacons blink off, locating the black boxes in such deep water would be an immensely difficult, if not impossible, task.