Searchers race to find jet's dying black boxes with no new underwater signals detected

Australian Prime Minister Tony Abbott leaves after a press conference at a hotel in Beijing, China Saturday, April 12, 2014. With no new underwater signals detected, the search for the missing Malaysian passenger jet resumed Saturday in a race against time to find its dying black boxes five weeks after families first learned their loved ones never arrived at their destination. (AP Photo/Andy Wong) (The Associated Press)

Australian Prime Minister Tony Abbott speaks during a press conference at a hotel in Beijing, China Saturday, April 12, 2014. Abbott told Chinese President Xi Jinping during their meeting on Friday that he was confident signals heard by an Australian ship towing a U.S. Navy device that detects flight recorder pings are coming from the missing Malaysian Airlines Flight 370. Officials believe the plane flew off course for an unknown reason and went down in the southern Indian Ocean off the west coast of Australia. (AP Photo/Andy Wong) (The Associated Press)

With no new underwater signals detected, the search for the missing Malaysian passenger jet has resumed in a race against time to find its dying black boxes five weeks after families first learned their loved ones never arrived at their destination.

The ocean search area has been condensed, as ships and planes continued to hunt Saturday for any clue that could help find Flight 370, which disappeared en route from Kuala Lumpur, Malaysia to Beijing with 239 people on board, mostly Chinese.

Australian Prime Minister Tony Abbott appeared to couch his comments from a day earlier while on a visit to China, where he met President Xi Jinping. He said Friday he was "very confident" signals heard by an Australian ship towing are coming from the Boeing 777.