Missing plane's black box batteries may have died

PERTH, Australia (AP) — Following four strong underwater signals in the past week, all has gone quiet in the hunt for the missing Malaysia Airlines jet, meaning the batteries in the plane's all-important black boxes may finally have died.

Despite having no new transmissions from the black boxes' locator beacons to go on, air and sea crews were continuing their search in the southern Indian Ocean on Sunday for debris and any sounds that may still be emanating. They are desperately trying to pinpoint where the Boeing 777 could be amid an enormous patch of deep ocean.

No new electronic pings have been detected since Tuesday by an Australian ship dragging a U.S. Navy device that listens for flight recorder signals. Once officials are confident that no more sounds will be heard, a robotic submersible will be sent down to slowly scour for wreckage.

"We're now into Day 37 of this tragedy," said aviation expert Geoffrey Thomas. "The battery life on the beacons is supposed to last 30 days. We're hoping it might last 40 days. However, it's been four or five days since the last strong pings. What they're hoping for is to get one more, maybe two more pings so they can do a triangulation of the sounds and try and narrow the (search) area."

Recovering the plane's flight data and cockpit voice recorders is essential for investigators to try to figure out what happened to Flight 370, which vanished March 8. It was carrying 239 people, mostly Chinese, while en route from Kuala Lumpur, Malaysia, to Beijing.

After analyzing satellite data, officials believe the plane flew off course for an unknown reason and went down in the southern Indian Ocean off Australia's west coast. Investigators trying to determine what happened to the plane are focusing on four areas — hijacking, sabotage and personal or psychological problems of those on board.