PERTH, Australia (AP) — Officials on Sunday were trying to confirm whether a "pulse signal" reportedly picked up by a Chinese ship in the Indian Ocean came from the missing Malaysian jetliner.
The Australian agency coordinating the search for the missing plane said that the electronic pulse signals reportedly detected by the Chinese ship are consistent with those of an aircraft black box.
But the agency's head, retired Air Chief Marshal Angus Houston, said they "cannot verify any connection" at this stage between the signals and Malaysia Airlines Flight 370, which disappeared March 8 en route from Kuala Lumpur to Beijing.
China's official Xinhua News Agency reported late Saturday that a Chinese ship that is part of the search effort detected a "pulse signal" at 37.5 kilohertz (cycles per second) — the same frequency emitted by flight data recorders — in southern Indian Ocean waters. Xinhua, however, said it had not yet been determined whether the signal was related to the missing plane, citing the China Maritime Search and Rescue Center.
Malaysia's civil aviation chief, Azharuddin Abdul Rahman, confirmed the frequency emitted by Flight 370's black boxes were 37.5 kilohertz.
Houston said his Joint Agency Coordination Centre had asked China for "any further information that may be relevant." He said the Australian air force was considering deploying more aircraft to the area where the Chinese ship reportedly detected the sounds.
"I have been advised that a series of sounds have been detected by a Chinese ship in the search area. The characteristics reported are consistent with the aircraft black box," Houston said. The agency had also received reports of white objects sighted on the ocean surface about 90 kilometers (56 miles) from where the electronic signals were detected.
"However, there is no confirmation at this stage that the signals and the objects are related to the missing aircraft," Houston said.
The agency said up to 12 military and civilian planes and 13 ships would take part in the search on Sunday, which would focus on three areas totaling about 216,000 square kilometers (83,400 square miles). The areas are about 2,000 kilometers (1,200 miles) northwest of the Australian city of Perth.
It was not immediately clear if the report of pulse signal being picked up helped to determine the areas to be searched on Sunday.
China has nine ships and eight planes in the southern Indian Ocean looking for the lost flight, according to an article on the China Maritime Rescue Center's website. The Haixun01, which Xinhua reported was the ship that detected the pulse signal, is equipped with sophisticated search equipment including underwater robots, an underwater sonar locator, and a black box locator, the article said.
After weeks of fruitless looking, the multinational search team is racing against time to find the sound-emitting beacons and cockpit voice recorders that could help unravel the mystery of the plane. The beacons in the black boxes emit "pings" so they can be more easily found, but the batteries only last for about a month.
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.
As officials tried to verify the Chinese reports, Malaysia's defense minister and acting transport minister, Hishammuddin Hussein, was hopeful. "Another night of hope — praying hard," he tweeted in response to the latest discoveries.
Australian Prime Minister Tony Abbott also expressed caution about the unconfirmed Chinese report.
"We are hopeful but by no means certain," Abbott said in comments on Australian Broadcasting Corp. television. "This is the most difficult search in human history. We need to be very careful about coming to hard and fast conclusions too soon."
There are many clicks, buzzes and other sounds in the ocean from animals, but the 37.5 kilohertz pulse was selected for underwater locator beacons on black boxes because there is nothing else in the sea that would naturally make that sound, said William Waldock, an expert on search and rescue who teaches accident investigation at Embry-Riddle Aeronautical University in Prescott, Arizona.
"They picked that (frequency) so there wouldn't be false alarms from other things in the ocean," he said.
Honeywell Aerospace, which made the boxes in the missing Malaysia Airlines plane, said the Underwater Acoustic Beacons on both the flight data recorder and cockpit voice recorder operate at a frequency of 37.5 kilohertz plus or minus 1 kilohertz.
Waldock cautioned that "it's possible it could be an aberrant signal" from a nuclear submarine if there was one in the vicinity.
If the sounds can be verified, it would reduce the search area to about 10 square kilometers (4 square miles), Waldock said. Unmanned robot subs with sidescan sonar would then be sent into the water to try to locate the wreckage, he said.
John Goglia, a former U.S. National Transportation Safety Board member, called the report "exciting," but cautioned that "there is an awful lot of noise in the ocean."
"One ship, one ping doesn't make a success story," he said. "It will have to be explored. I guarantee you there are other resources being moved into the area to see if it can be verified."
Hishammuddin told reporters in Kuala Lumpur on Saturday the cost of mounting the search was immaterial compared to providing solace for the families of those on board by establishing what happened.
"I can only speak for Malaysia, and Malaysia will not stop looking for MH370," he said.
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, China, the United States, Britain and France, Hishammuddin said.
Officials have said the hunt for the wreckage is among the hardest ever undertaken, and will get much harder if there are no confirmed debris sightings and the beacons fall silent before they are found.
If that happens, 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.
The search agency said Friday that sophisticated sound locating equipment from the U.S. Navy had been deployed for the first time from the Australian navy vessel Ocean Shield. The British navy ship HMS Echo was fitted with similar equipment.
Because the U.S. Navy's pinger locator can pick up signals to a depth of 6,100 meters (20,000 feet), 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 meters (19,000 feet). 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 1 to 5 knots (1 to 6 mph).
Ng reported from Kuala Lumpur, Malaysia. Associated Press writers Gillian Wong in Kuala Lumpur, Rod McGuirk in Canberra, Australia, Kristen Gelineau and Rohan Sullivan in Sydney, and Joan Lowy in Washington contributed to this report.