PERTH, Australia (AP) - Rain was expected to hamper the hunt Monday for the missing Malaysia Airlines jet, as a growing number of planes focus on an expanded area of the south Indian Ocean where a French satellite detected potential debris.
Australian Maritime Safety Authority's rescue coordination center said the search area was expanded from 59,000 to 68,500 square kilometers (22,800-26,400 square miles), including a new separate area because of data provided by France on Sunday.
The U.S. Pacific command said it was sending a black box locator to the region in case a debris field is located. The Towed Pinger Locator has highly sensitive listening capability so that if the wreck site is located, it can hear the black box pinger down to a depth of about 20,000 feet (6,100 meters), Cmdr. Chris Budde, a U.S. Seventh Fleet operations officer, said in a statement.
Two Chinese Ilyushin IL-76 planes joined the search from Perth, increasing the number of aircraft to 10 from eight a day earlier, AMSA said.
It said the weather in the search area, about 2,500 kilometers (1,550 miles) southwest of Perth, was expected to deteriorate with rain likely.
Australian Transport Minister Warren Truss said "nothing of note" was found Sunday, which he described as a "fruitless day."
"It's going to be a challenge, but we'll stick at it," he told Australian Broadcasting Corp. radio before the first aircraft left Perth at dawn.
He said that the latest search area based on French radar data was 850 kilometers (530 miles) north of the previous search zone. He said it was not the same area that had been identified as the most likely place where the aircraft may have entered the sea, "but ... we've got to check out all the options."
"We're just, I guess, clutching at whatever little piece of information comes along to try and find a place where we might be able to concentrate the efforts," he added.
A cyclone bearing down on the Australian northwest coast "could stir up less favorable weather," he said.
Flight 370 vanished March 8 with 239 people aboard while en route from Kuala Lumpur, Malaysia, to Beijing, setting off a multinational search that has turned up no confirmed pieces and nothing conclusive on what happened to the jet.
The latest French satellite data came to light on Sunday as Australian authorities coordinating the search sent planes and a ship to try to locate a wooden pallet that appeared to be surrounded by straps of different lengths and colors.
The pallet was spotted on Saturday from a search plane, but the spotters were unable to take photos of it.
Wooden pallets are most commonly used by ships but are also used airplane cargo holds, and an official with Malaysia Airlines said Sunday night that the flight was, in fact, carrying wooden pallets. The official spoke on condition of anonymity in keeping with company policy.
AMSA said it has requested a cargo manifest from Malaysia Airlines.
In Paris, French Foreign Ministry spokesman Romain Nadal said in an interview with The Associated Press that the satellite radar echoes "identified some debris that could be from the Malaysian Airlines plane."
The spokesman said that these echoes "are not images with a definition like a photograph, but they do allow us to identify the nature of an object and to localize it."
"The French government has decided to increase its satellite monitoring of this zone and try to obtain precise images and locations," Nadal said.
Gathering satellite echo data involves sending a beam of energy to the Earth and then analyzing it when it bounces back, according to Joseph Bermudez Jr., chief analytics officer at AllSource Analysis, a commercial satellite intelligence firm.
Satellite radar echoes can be converted into an image that would look similar to a black-and-white photo, though not as clear, he said. "You'd have to know what you're looking at," Bermudez said.
A Malaysian official involved in the search said the French data located objects about 930 kilometers (575 miles) north of the spots where the objects in the images released by Australia and China were located.
One of the objects located was estimated to be about the same size as an object captured Tuesday by the Chinese satellite that appeared to be 22 meters (72 feet) by 13 meters (43 feet), said the official, who declined to be identified because he wasn't authorized to speak to the media. It was not possible to determine precise dimensions from the French data, the official said.
U.S. underwater wreck hunter David Mearns on Monday described the French satellite sighting of potential debris as a "positive development," although he was unaware of the full details.
Mearns was an adviser to British and French search authorities following the loss of Air France Flight 447 in the Atlantic Ocean during a flight from Brazil to Paris in 2009.
He warned that time was running out to find confirmed wreckage that could lead searchers back to the aircraft's black box. He told the AP that two satellite images of a large object spotted in the Indian Ocean two days apart could be the breakthrough needed to find the wreckage.
"The odds are still against the plane being found at the moment, but at least we have a glimmer of hope that we didn't have two days ago," Mearns said. "Right now, time is running out very quickly."
The southern Indian Ocean is thought to be a potential area to find the jet because Malaysian authorities have said pings sent by the Boeing 777-200 for several hours after it disappeared indicated that the plane ended up in one of two huge arcs: a northern corridor stretching from Malaysia to Central Asia, or a southern corridor that stretches toward Antarctica.
Malaysian authorities have not ruled out any possible explanation for what happened to the jet, but have said the evidence so far suggests it was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.
Authorities are considering the possibilities of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or someone else on board.
In the U.S., Tony Blinken, President Barack Obama's deputy national security adviser, said on CNN: "There is no prevailing theory."
"Publicly or privately, we don't know" what happened to the plane, he said. "We're chasing down every theory."
McDonald reported from Kuala Lumpur, Malaysia. Associated Press writers Todd Pitman and Eileen Ng in Kuala Lumpur, Kristen Gelineau in Sydney, Cassandra Vinograd in London, and Elaine Ganley and Oleg Cetinic in Paris contributed to this report.