The first plane sent Friday to fly over one of the remotest places on Earth returned empty-handed from its hunt through rough seas for objects that may be from the missing Malaysia Airlines plane, Australian officials said.
Another three planes were still in the area trying to help solve the nearly 2-week-old aviation mystery, and another was on the way to look for two large objects a satellite detected floating off the southwest coast of Australia about halfway to the desolate islands of the Antarctic.
The area in the southern Indian Ocean is so remote is takes aircraft four hours to fly there and four hours back, and leaves them only about two hours to search.
The satellite discovery raised new hope of finding the vanished jet and sent another emotional jolt to the families of the 239 people aboard.
A search Thursday with four planes in cloud and rain found nothing, and so far efforts Friday were the same, with a Royal Australian Air Force P3 Orion plane flying back to Australia.
Two more Orions and an ultra-long-range Bombardier Global Express were still scouring the area 2,300 kilometers (1,400 miles) from western Australia, according to the Australian Maritime Safety Authority.
A US Navy P-8 Poseidon aircraft also was in the air, but like the other planes, once it arrives it will have enough fuel for only two to three hours of search time before returning to Perth.
Lisa Martin, spokeswoman for the Australian Maritime Safety Authority, said weather conditions were getting better as the day wore on, with moderate seas and some cloud cover, and improving visibility.
Mike Yardley, an air commodore with New Zealand's air force, said the search Thursday was hampered when an Orion was forced to duck below thick clouds and fog to a very low altitude of 60 meters (200 feet).
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But Yardley was optimistic that the searchers will find the objects. "We will find it - I'm sure about that piece of it. The only reason we wouldn't find it was that it has sunk," he said of the large unidentified object spotted by the satellite.
"I've been on these missions before when it's taken a few days to come across it," he said.
Speaking at a news conference in Papua New Guinea, Australian Prime Minister Tony Abbott said, "We've been throwing everything we've got at that area to try to learn more about what this debris might be."
He said that the objects "could just be a container that's fallen off a ship - we just don't know."
Abbott spoke with Chinese President Xi Jinping, whom he described as "devastated." Of the 227 passengers on the missing flight, 154 were from China.
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"It's about the most inaccessible spot that you could imagine on the face of the earth, but if there is anything down there we will find it. We owe it to the families of those people to do no less," Abbott said.
The development also marked a new phase for the anguished relatives of the passengers, who have been critical of Malaysian officials for what the relatives say has been the slow release of timely information.
In Beijing, relatives met Friday with Malaysian officials at the Lido Hotel, where most have been staying awaiting the latest news. Those who spoke said they had a two-hour briefing about the search but that nothing new was said.
Wang Zhen, son of artist Wang Linshi, said the meeting went smoothly but that there were questions on why Malaysian authorities had provided so much seemingly contradictory information.
Wang said he has hopes his father can be found alive and was praying that the Australian reports turn out to be false. He said he and other relatives are suspicious about what they were being told by the Malaysian side, but are at a loss as to what to do next.
"We feel they're hiding something from us," said Wang, who was filling his days attending briefings and watching the news for updates.
Another relative, Nan Jinyan, sister-in-law of passenger Yan Ling, said hope was slipping away.
"I'm psychologically prepared for the worst and I know the chances of them coming back alive are extremely small," she said.
One of the objects on the satellite image was 24 meters (almost 80 feet) long - which is longer than a standard container - and the other was 5 meters (15 feet).
The Norwegian cargo vessel Hoegh St. Petersburg, with a Filipino crew of 20, arrived in the area and used lights to search overnight before resuming a visual search Friday, said Ingar Skiaker of Hoegh Autoliners, speaking to reporters in Oslo.
The Norwegian ship, which transports cars, was on its way from South Africa to Australia, he said. The Australian Maritime Safety Authority said another commercial ship and an Australian navy vessel were also en route to the search area.
Three Chinese naval ships were heading to the area, along with the icebreaker Snow Dragon, China's state television reported. The icebreaker was in Perth following a voyage to the Antarctica in January, but it wasn't clear when the other ships would get there.
There have been several false leads since the Boeing 777 disappeared March 8 above the Gulf of Thailand en route from Kuala Lumpur to Beijing, and one analyst cautioned against rising hopes the objects are from Malaysia Airlines Flight 370.
"The chances of it being debris from the airplane are probably small, and the chances of it being debris from other shipping are probably large," said Jason Middleton, an aviation professor at the University of New South Wales in Sydney.
The hunt has encountered other false leads. Oil slicks that were seen did not contain jet fuel. A yellow object thought to be from the plane turned out to be sea trash. Chinese satellite images showed possible debris, but nothing was found.
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.
Police are considering the possibility of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or anyone else on board.