(USA TODAY) With no pings from its black boxes detected for nearly a week, search operations for missing Malaysian Airline Flight 370 intensified Sunday, with more than two dozen ships and aircraft scouring the southern Indian Ocean for signs of debris.
The search area covers about 22,200 square miles of ocean nearly 1,400 miles northwest of Perth, Australia.
"No one should underestimate the difficulties of the task still ahead of us,'' said Australian Prime Minister Tony Abbott, who noted the search could continue "a long time."
The flight went missing March 8 after departing Kuala Lumpur for Beijing with 239 passengers and crew on board. The aircraft's black box flight recorder batteries have a life of about 30 days. But no new electronic pings have been detected since Tuesday. Officials now fear the black box batteries have now died, and if no more pings are detected soon, a robotic submersible will be sent down to slowly scour the ocean floor 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 in determining what happened to the Boeing 777.
From 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.
Two sounds heard a week ago by the Australian ship Ocean Shield, which was towing the ping locator, were determined to be consistent with the signals emitted from the black boxes. Two more pings were detected in the same general area Tuesday, but no new ones have been picked up since then.
"There's still a lot more work to be done and I don't want anyone to think that we are certain of success, or that success, should it come, is going to happen in the next week or even month. There's a lot of difficulty and a lot of uncertainty left in this," Abbott said.
Searchers want to pinpoint the exact location of the source of the sounds — or as close as they can get — before sending the Bluefin 21 submersible down. It will not be deployed until officials are confident that no other electronic signals will come, and that they have narrowed the search area as much as possible.
The sub takes six times longer to cover the same area as the ping locator, and will need about six weeks to two months to canvass the current underwater zone. The signals are also coming from 15,000 feet below the surface, which is the deepest the sub can dive.