Pings 'consistent' with expectations for black boxes raise hope of finding jet

An Australian aircraft detected a signal on Thursday that was possibly coming from one of the black boxes of missing Malaysia Airlines Flight MH370, an Australian official leading the search confirmed.

Angus Houston, chief coordinator of Australia's Joint Agency Coordination Center, confirmed that an AP-3C Orion aircraft from the Australian air force detected "a possible signal in the vicinity of the Australian Defense Vessel Ocean Shield", the center said in a statement.

"The acoustic data will require further analysis overnight but shows potential of being from a man-made source," Houston said. "I will provide a further update if, and when, further information becomes available."

Finding one of the flight's black boxes soon is important because their locator beacons have a battery life of about a month. Tuesday marked one month since the flight vanished en route from Kuala Lumpur, Malaysia, to Beijing with 239 people aboard.

Planes and ships hunting for the missing jetliner zeroed in on a patch of the Indian Ocean on Thursday, after an Australian ship picked up underwater signals that are consistent with a plane's black box.

Thursday's search zone was the smallest yet in the monthlong hunt for MH370 as the Australian Maritime Safety Authority designated a search area of nearly 58,000 sq km, 2,280 km northwest of Perth.

Up to 14 planes and 13 ships assisted in Thursday's search.

The Ocean Shield, towing a United States navy pinger locator, is now focused on a far smaller area of the Indian Ocean where it picked up two fresh signals on Tuesday.

Those transmissions matched a pair of signals logged over the weekend.

"When you put those two together, it makes us very optimistic," said Commander William Marks, the US 7th Fleet spokesman. He added that the search was getting "closer and closer".

"This is not something you find with commercial shipping, not something just found in nature - this is definitely something that is man-made, consistent with what you would find with these black boxes."

He told CNN he expected the pings to last "maybe another day or two".

No floating debris from the aircraft has yet been found despite days of exhaustive searching by ships and aircraft from several nations.

The center said on Thursday that searchers had not yet deployed an unmanned submarine to create a sonar map of a potential debris field on the seabed.

It also confirmed that the Australian Transport Safety Bureau is continuing to refine the area where the missing aircraft is thought to have entered the water.

The narrowing of that area is based on continuing multidisciplinary technical analysis of satellite communication and aircraft performance, passed from the international air crash investigative team, according to the command center.

In Malaysia, Home Minister Zahid Hamidi said there was "no conclusive evidence yet" from the investigation into what caused the plane to divert from its Kuala Lumpur-Beijing route.

Zahid, who oversees law enforcement, said around 180 people had been interviewed, including relatives of passengers and crew, and airline ground staff and engineers.

"We are filtering all the information. When the evidence is conclusive then we will let the media know about it," he said.

Xinhua and agencies contributed to this story.