By Michael Pearson and Jethro Mullen, CNN
Despite better weather, the first of five search planes dispatched to look for floating debris that could be related to missing Malaysia Airlines Flight 370 returned to base Friday without spotting anything of note.
The surveillance planes are looking for two objects photographed by a commercial satellite Sunday bobbing in the remote and treacherous waters of the southern Indian Ocean more than 1,400 miles from the west coast of Australia.
Aircraft and a merchant ship scoured the area Thursday but found nothing in a search hindered by poor weather.
Flight 370 vanished 14 days ago with 239 people aboard, and the announcement Thursday by Australian officials that they had spotted something raised hopes of a breakthrough in the frustrating search.
On Friday, Australian Prime Minister Tony Abbott defended the decision to announce the find, saying that Australia owes it to families of those missing “to give them information as soon as it’s to hand, and I think I was doing that yesterday in the Parliament.”
But he reiterated a warning that the two objects may not be related to the search for the plane.
“It could just be a container that has fallen off a ship,” he said during a visit to Papua New Guinea. “We just don’t know.”
His words have focused worldwide attention on Australia’s part in the massive international hunt for the jetliner, which disappeared on March 8 over Southeast Asia with 239 people on board.
Almost two weeks after the Boeing 777-200 dropped off radar screens, authorities still don’t know why it veered dramatically off course or where it ended up.
On Friday, Hishammuddin Hussein, Malaysia’s interim transportation minister, tried to reset expectations for a quick resolution to the mystery surrounding the plane.
“This is going to be a long haul,” he said.
Conditions for the southern Indian Ocean search have improved since Thursday, said John Young, emergency response manager for the Australian Maritime Safety Authority. Flight crews are searching for the objects visually rather than using radar, he said.
“That’s encouraging,” he said. “But we have no sightings yet.”
Given the distance from Australia to where the objects were spotted by the satellite, the aircraft have about two hours in the search area before having to start the return journey.
Young cautioned that the search zone is “a big area when you’re looking out the window trying to see something by eye.”
The flight crews may have to repeat flights like those undertaken Thursday and Friday “a few times” before they can be confident of having covered the whole area, he said.
Along with the aircraft, a motley collection of merchant ships are heading to the search area, where they will join a massive Norwegian cargo ship diverted there Thursday at the request of Australia.
The sailors aboard the Norwegian ship worked throughout the night looking for the objects, said Erik Gierchsky, a spokesman for the Norwegian Shipowners Association.
If the objects are determined to be debris from Flight 370, experts say that search teams may then use locators to try to find pings coming from the plane’s flight data recorder.
Hishammuddin tweeted Friday that the search and rescue teams working across a wide area of the Indian Ocean are in need of the locators, also known as hydrophones. He said not many countries have them.
Hishammuddin said his country had asked for specialized assets from the United States, including remotely operated submersibles, to aid in the search and eventual recovery.
He also said the United Kingdom was sending the HMS Echo to the scene to aid a growing international force searching the southern Indian Ocean. The ship is an ocean surveying vessel, according to the UK Defense Ministry website.
Chinese and Malaysian vessels are also steaming to the area to join the Norwegian merchant vessel already there.
Hishammuddin said he would be speaking to U.S. Defense Secretary Chuck Hagel on Friday.
The batteries that power the pings from the flight recorder have a life expectancy of 30 days, meaning they will probably last about another 16 days.
But one expert warns that the depths of the Indian Ocean may make it hard to put the hydrophones to use.
“At this water depth, the range is very limited on listening to those pingers,” said Mike Williamson, who runs a Seattle engineering firm specializing in deep-sea searches of planes and shipwrecks.
Search continues elsewhere
Countries from central Asia to Australia continue to search for the plane along an arc drawn by authorities based on satellite pings received from the plane for hours after it vanished. One of those arcs tracks the southern Indian Ocean zone that’s the focus of current attention.
The other tracks over parts of Cambodia, Laos, China and into Kazakhstan, where authorities said Thursday they had found no trace of the plane.
Hishammuddin said Friday that Malaysian authorities were awaiting permission from Kazakhstan’s government to use the country as a staging area for the northern corridor search.
That clearly signals that Malaysian authorities are not ready to give up on the possibility the plane could still be found far from the focus of current search efforts.
“Obviously, the search now has taken a global perspective,” Hishammuddin said.
Deleted files sought
Malaysian authorities say they believe that the missing plane was deliberately flown off course during its scheduled flight from Kuala Lumpur to Beijing. But they haven’t so far found any clear evidence to indicate who might have changed the plane’s path and why.
The pilot and first officer of the plane have come under particular scrutiny, especially in light of information suggesting a sharp turn in the flight path had been programmed into the plane’s flight management system before one of the pilots gave a routine sign-off to Malaysian air traffic controllers.
Question marks remain over data that authorities say was deleted from the hard drive of a flight simulator found at the home of the plane’s pilot, Capt. Zaharie Ahmad Shah.
On Thursday, a U.S. official familiar with the investigation told CNN that an FBI team is confident that it will be able to retrieve at least some of the deleted files.
Investigators will also analyze websites that Zaharie and the first officer, Fariq Ab Hamid, may have visited recently, the official said on the condition of anonymity.
Passengers also continue to be investigated. On Friday, Hishammuddin said Ukraine told Malaysia that background checks on its citizens aboard the plane had come back clear.
The delays have frustrated and angered family members, some of whom have accused Malaysian officials of withholding information, or at the very least failing to update them.
For the first time since the plane disappeared, Malaysia sent a high-level delegation to Beijing to brief relatives who had opted not to travel to Malaysia to wait out the search.
Hishammuddin said the 3½-hour meeting went as well as could be expected given the lack of information about what happened to the plane.
“Although we answered most of the questions they raised, we could not answer them all,” he said.
“The one question that they really want to know is the answer to which we do not have,” he said, “which is: ‘Where are their loved ones, and where is the airplane?’ “
CNN’s Mitra Mobasherat, Kyung Lah, Chelsea J. Carter, Mike Pearson, Brian Walker, Elizabeth Joseph, Evan Perez and Shimon Prokupecz contributed to this report.
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