A pinger locator on an Australian navy ship searching for the missing Malaysia Airlines jet has detected signals consistent with transmissions from aircraft black boxes, according to the official coordinating the search.
At a news conference just after noon Monday (12 a.m. ET), retired Australian Air Chief Marshal Angus Houston described the possible signals as the "most promising lead and probably, so far, the best information that we have had" in the search for the vanished Boeing 777.
"We've got a visual indication on a screen and we've also got an audible signal — and the audible signal sounds to me just like an emergency locator beacon," Houston added. "I'm much more optimistic than I was a week ago."
The first signal lasted two hours and 20 minutes before it was lost. The ship then turned around and picked up a signal again — this time recording two distinct "pinger returns" that lasted 13 minutes, Houston said.
However, he cautioned that it may take days to confirm whether signals picked up by the device affixed to the Australian Royal Navy vessel Ocean Shield are from the voice and data recorders on doomed Flight MH370.
Houston said the position of the "pings" — the signals emitted by the so-called black boxes — needs to be further refined. Then, an underwater autonomous vehicle — the Bluefin-21 — can be sent to investigate.
But that may prove tricky, given that the sub can only dive to about 14,800 feet — the approximate depth of the water. That means the vehicle will be operating to the limits of its capability.
Over the weekend, investigators hunting for the aircraft detected three sonic pings that may have been emitted by the black box. The Chinese vessel Haixun 01 detected three separate pulse signals on Friday and again on Saturday. The Australian ship Ocean Shield picked up a signal Sunday.
Investigators are in a race against time to find the airplane's black boxes before the battery-run ping they transmit runs out of power.
The beacons' batteries last only about a month — and Tuesday marks exactly one month since the plane disappeared
The jet vanished March 8 with 239 passengers and crew on a routine flight from Kuala Lumpur to Beijing.
Daniel Arkin of NBC News and The Associated Press contributed to this report.