By Julie Makinen, Los Angeles Times

BEIJING — An Australian military plane participating in the search for missing Malaysia Airlines Flight 370 on Thursday detected an underwater acoustic signal that may be from the Boeing 777’s black boxes, Australian authorities said.

The P-3 Orion has been dropping buoys equipped with hydrophones that can pick up such signals and transmit them back to the aircraft. The buoys have been dropped in the area of the Indian Ocean where the Australian ship Ocean Shield, towing a “pinger locator” lent by the U.S. Navy, has four times picked up acoustic signals that investigators believe are being transmitted from the jet’s black boxes.

“The acoustic data will require further analysis overnight but shows potential of being from a man-made source,” Air Chief Marshal Angus Houston, who is coordinating search efforts out of Perth, Australia, said in a statement.

Thursday’s search team consisted of up to 10 military planes, four civil aircraft and 13 ships. Searchers have yet to find any debris from the jet, which disappeared March 8 en route from Kuala Lumpur to Beijing with 239 people aboard. The search was centered about 1,400 miles northwest of Perth and covered an area of about 22,000 square miles.

With batteries on the black box pingers expected to run out very soon, investigators are eager to detect as many signals as possible to narrow the search field before deploying underwater vehicles to look for wreckage.

AFP Photo/Eric A. Pastor