(CNN) -- Nearly three weeks after the disappearance of Malaysia Airlines Flight 370, the focus of the hunt for the missing passenger jet has moved yet again.
Search teams have shifted to a different part of the southern Indian Ocean after Australian authorities said they received "a new credible lead" about the jetliner's most likely last movements.
An analysis of radar data led investigators to move the search to an area 1,100 kilometers (680 miles) to the northeast of where efforts had been focused previously, the Australian Maritime Safety Authority said Friday.
It described the new information, which indicated the errant jetliner didn't fly as far south as previously thought, as "the most credible lead to where debris may be located."
That means the huge, isolated areas of the ocean that ships and planes had combed for more than a week -- and where various satellites detected objects that might be debris from the missing plane -- are no longer of interest.
"We have moved on from those search areas," said John Young, general manager of emergency response for the Australian maritime authority.
The new search area is "considerable" and conditions there "remain challenging," acting Malaysian Transport Minister Hishammuddin Hussein told reporters Friday.
The sudden change of geographic focus is the latest twist in an investigation that has so far failed to establish why Flight 370 flew dramatically off course or exactly where the plane and the 239 people it was carrying ended up.
"To me, it's not a game changer, it's a reset," David Gallo of the Woods Hole Oceanographic Institution said of the shifted search.
'We have not seen any debris'
Australian officials also played down the significance of hundreds of possible objects detected by satellites in the previous search region, some of which had been described by authorities as important leads.
"In regards to the old areas, we have not seen any debris," Young said at a news briefing in Canberra, the Australian capital. "And I would not wish to classify any of the satellite imagery as debris, nor would I want to classify any of the few visual sightings that we made as debris. That's just not justifiable from what we have seen."
Officials had repeatedly cautioned that the objects seen in the satellite imagery could just be flotsam that had fallen off cargo ships.
But Hishammuddin said the new search area "could still be consistent" with the idea that materials spotted in recent satellite photos over the previous search area are connected to the plane. The materials could have drifted in ocean currents, he said.
Some analysts raised their eyebrows at the search coordinators' readiness to move away from the satellite sightings.
"Really? That much debris and we're not going to have a look at it to see what that stuff might be?" said Gallo, who helped lead the search for the flight recorders of Air France Flight 447, which crashed into the Atlantic Ocean in 2009.
Others lamented the amount of time, money and resources that were spent sending planes and ships out to the now discounted areas for more than a week.
"This is time that has been wasted, there's no question," said CNN aviation analyst Miles O'Brien.
But Young disputed that suggestion, saying the previous searches were based on the information authorities "had at the time."
"That's nothing unusual for search and rescue operations," he said "And this actually happens to us all the time -- that new information may arise out of sequence with the search itself."
Plane traveled faster
The latest data, based on an analysis of radar on the night Flight 370 disappeared, suggest the aircraft was traveling faster than previously estimated before it dropped off radar, Australian authorities said.
The radar data concerns the phase of the flight during which the plane turned off its original path over the South China Sea and headed west over the Malay Peninsula out into the Strait of Malacca, authorities said.
The faster speed means the plane is thought to have burned more fuel than previously calculated, shortening the possible distance it flew south into the Indian Ocean.
CNN safety analyst David Soucie said it was "a good sign" that international aviation experts analyzing the radar and satellite data related to the plane had adjusted their assumptions.
"Assumptions are the key to all of this," he said. "If you assume something and you end up with a final conclusion, you have to constantly review that."
Less remote, better weather
The new search area is closer to the Australian continent, allowing planes to spend longer flying over it as they hunt for traces of the missing passenger jet, which disappeared March 8 over Southeast Asia.
"We will certainly get better time on scene," Young said.
The new zone is also farther north, moving search teams away from latitudes known for difficult weather conditions. Search efforts in the old areas were disrupted twice this week by bad weather.
Conditions in the more northerly zone are "likely to be better more often than we've seen in the past," Young said.
They may also be better for taking satellite images, he said. The Australian Geospatial-Intelligence Organisation has directed satellites to capture images of the new zone.
Aircraft searching new zone
But the area in question remains vast -- roughly 319,000 square kilometers (123,000 square miles) -- and remote -- about 1,850 kilometers (1,150 miles) west of Perth, the western Australian city that's the hub for search operations.
The waters there are also deep, between 2,000 and 4,000 meters (6,500 and 13,000 feet).
Ten search aircraft will fly over the area Friday. Six ships involved in the search -- one Australian and five Chinese -- are headed there, too. One Chinese patrol ship is already in the search area, authorities said.
American flight crews involved in the search aren't frustrated or disillusioned by the sudden change in the search, said Cmdr. William Marks of the Navy's U.S. 7th Fleet.
"For the pilots and the air crews, this is what they train for," he said. "They understand it."
The focus of the search teams is "to get a visual confirmation of debris," Marks said, noting that any parts of the plane still afloat in the ocean could easily have moved 60-80 miles from where it hit the water.
Vast, evolving search
The shifting hunt for the plane has spanned oceans and continents over the past three weeks.
It started in the South China Sea between Malaysia and Vietnam, where Flight 370 lost contact with air traffic controllers in the early hours of March 8.
As news of the disappearance spread, authorities became aware of Malaysian military radar data suggesting the plane might have turned west after contact was lost. As a result, they expanded the search out into the Strait of Malacca, off the west coast of the Malay Peninsula.
As those efforts proved fruitless, the search spread north into the Andaman Sea and northern Indian Ocean.
It then ballooned dramatically after Malaysia announced on March 15 that satellite data suggested the plane's last position was somewhere along two huge arcs, one stretching northwest into the Asian landmass, the other southwest into the Indian Ocean.
The total search area at that point reached almost 3 million square miles.
On Monday, Malaysian Prime Minister Najib Razak said that further analysis of satellite data had led authorities to conclude that the plane went down in the southern Indian Ocean, far from land.
Malaysian officials told the families of those on board that nobody would have survived. But many relatives have said that only the discovery of wreckage from the plane will convince them of the fate of their loved ones.
CNN's Brian Walker and Ben Brumfield contributed to this report.
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