The head of the multinational search for the missing Malaysian jetliner says that an Australian ship detected an 'acoustic event' early Sunday morning and that a Chinese ship has reported a second pulse consistent with an aircraft black box in a different location, though the Chinese reports could not be verified.

Australian Air Chief Marshal Angus Houston said that Ocean Shield, an Australian vessel, is closely investigating a stretch of the southern Indian Ocean after picking up an acoustic occurrence. Houston called it an encouraging development but cautioned that very little is currently known about the nature of the transmission.

The Ocean Shield is carrying sophisticated U.S. Navy equipment designed to pick up signals sent from the black boxes, which may hold the key to why the aircraft ended up thousands of kilometres off course.

Houston also said that Chinese authorities have told Australian officials that Haixun 01, the ship that on Friday reportedly picked up an electronic pulse at 37.5 kilohertz (thousands of cycles per second) — the same frequency emitted by flight data recorders — detected a series of pulses that lasted approximately 90 seconds on Saturday afternoon.

The pulses were heard about 2 kilometres from the previous signal that Haixun 01 reported. Australian ship Echo and multiple airplanes are on their way to assist Haixun 01 search that area, while Ocean Shield will move to the location of those reported pulses if nothing comes of the 'acoustic event' it picked up Sunday morning.

"Ocean Shield is in the process of exploiting another acoustic event that we need to look into to determine if there's anything to it. This is a painstaking process and if we get any leads whatsoever, we investigate them," Houston said.

Australian ship Ocean Shield detected an 'acoustic event' on Sunday morning. If the vessel's investigation of the occurrence does not turn up any new leads, it will head south to assist the Chinese ship Haixun 01 in its search. (Jason Reed/Reuters) According to Houston, the international investigative team has also concluded that their original interpretation of satellite flight path data underestimated the speed of the jet, and that it may have travelled farther south than previously believed. The southern region of the search area — where Haixun 01 is currently operating in waters about 4,500 metres deep — will now be more heavily prioritized.

"The area of the highest probability is, what we think, the southern part where Haixun 01 is operating. That is why we are really interested in the two acoustic encounters that Haixun 01 has had."

Because the pinger locator can pick up signals to a depth of 6,100 metres, it should be able to hear the plane's data recorders even if they are in the deepest part of the search zone — about 5,800 metres. But that's only if the locator gets within range of the black boxes — a tough task, given the size of the search area and the fact that the pinger locator must be dragged slowly through the water at just a few kilometres per hour.

If the signals detected by Haixun 01 are confirmed, it will take a "long period of time" to recover the black boxes, Houston said.

"That's incredibly deep. Four and a half kilometres, straight down. Any recovery operation is going to be incredibly challenging."

The Boeing 777 disappeared March 8 while en route from Kuala Lumpur, Malaysia, to Beijing with 239 people aboard. So far, no trace of the jet has been found.

Confirmation would be 'astronomical luck'

Airline technology consultant Michael Planey says with no other clues found, searchers would have to have "astronomical luck" to be led to the black boxes with just this kind of signal.

"I hate to say at this point that anything is a significant announcement. We've been down so many blind paths and wrong alleys and everything in the search and what's been reported that I don't want to be overly hopeful," Planey told CBC News on Saturday, speaking from Alexandria, Va.

Chinese patrol ship Haixun 01 reported on Saturday that its black box detector picked up a pulse signal that is consistent with the 'pings' emitted from an airliner's black box. Those reports have not been independently verified. (CNSphoto/Reuters) "It would be truly incredible luck to blindly stumble across the ping from the black box, with no other debris having been located, with no other clues that this could be from that missing Malaysian aircraft," he said.

"The reality is, the frequency that [Haixun 01] detected is the same frequency that is used in almost all emergency locator pingers and in a number of other sea-going devices. So it could be attached to another random piece of equipment that has fallen off of a cargo ship," Planey said.

After weeks of fruitless looking, searchers face the daunting prospect that sound-emitting beacons in the flight and voice recorders will soon fall silent as their batteries die after sounding electronic "pings" for a month.

Officials have said the hunt for the wreckage is among the hardest ever undertaken, and will get much harder still if the beacons fall silent before they are found.

"We are running out of time in terms of the battery life of the emergency locator beacon," Angus said.

If the flight data recorder is not found, the only hope for finding the plane may be a full survey of the Indian Ocean floor, an operation that would take years and an enormous international operation.

John Goglia, a former U.S. National Transportation Safety Board member, cautioned that "there is an awful lot of noise in the ocean."

Search continues

According to a release from the Australian Maritime Safety Authority released Sunday, up to 10 military aircraft, two civilian planes and 13 ships will assist in the day's search for debris or any sign of the jet.

Malaysia will not stop looking for MH370 - Hishammuddin Hussein, Malaysian defence and transportation minister

Weather in the search area — about 216,000 square kilometres in the southern Indian Ocean — is expected to be good, with visibility greater than 10 kilometres.

Malaysia's defence minister and acting transport minister, Hishammuddin Hussein, was hopeful. "Another night of hope — praying hard," he tweeted in response to the latest discoveries.

Malaysia vowed Saturday that it would not give up trying to find the missing jetliner and said a multinational investigation team would to try to solve the aviation mystery.

Military and civilian planes, ships with deep-sea searching equipment and a British nuclear submarine scoured a remote patch of the southern Indian Ocean off Australia's west coast, in an increasingly urgent hunt for debris and the black box recorders that hold vital information about Malaysia Airlines Flight 370's last hours.

"I can only speak for Malaysia, and Malaysia will not stop looking for MH370," Hishammuddin said.

Hishammuddin told reporters in Kuala Lumpur that the cost of mounting the search was immaterial compared to providing solace for the families of those on board by establishing what happened.

A woman ties a message card for passengers who were aboard missing Malaysia Airlines Flight MH370, at a shopping mall in Kuala Lumpur, Malaysia on Saturday. (Lai Seng Sin/Associated Press) He said an independent investigator would be appointed to lead a team that will try to determine what happened to Flight 370. The team will include three groups: one will look at airworthiness, including maintenance, structures and systems; another will examine operations, such as flight recorders and meteorology; and a third will consider medical and human factors.

The investigation team will include officials and experts from several nations, including Australia — which as the nearest country to the search zone is currently heading the hunt — China, the U.S., Britain and France, Hishammuddin said.

Finding floating wreckage is key to narrowing the search area, as officials can then use data on currents to backtrack to where the plane hit the water, and where the flight recorders may be.