Kuala Lumpur, Malaysia CNN-- As a growing number of airplanes scoured the southern Indian Ocean in the search for Malaysia Airlines Flight 370, authorities released new details Sunday that paint a different picture of what may have happened in the plane's cockpit.
Military radar tracking shows that the aircraft changed altitude after making a sharp turn over the South China Sea as it headed toward the Strait of Malacca, a source close to the investigation into the missing flight told CNN. The plane flew as low as 12,000 feet at some point before it disappeared from radar, according to the source.
The sharp turn seemed to be intentional, the source said, because it would have taken the Boeing 777 two minutes to execute it, a notable time period for anyone on board to notice.
The official, who is not authorized to speak to the media, told CNN that the area the plane flew in after the turn is a heavily trafficked air corridor and that flying at 12,000 feet would have kept the jet well out of the way of that traffic.
Earlier Sunday, Malaysian authorities said the last transmission from the missing aircraft's reporting system showed it heading to Beijing -- a revelation that appears to undercut the theory that someone reprogrammed the plane's flight path before the co-pilot signed off with air-traffic controllers for the last time.
That reduces, but doesn't rule out, suspicions about foul play in the cockpit.
The new details give more insight about what happened on the plane, but don't explain why the plane went missing or where it could be.
Analysts are divided about what the latest clues about what happened aboard the plane could mean. Some argue the new information is a sign that mechanical failure sent the plane suddenly off course. Others say there are still too many unknowns to eliminate any possibilities.
CNN aviation analyst Miles O'Brien called the fresh information about the flight a "game changer."
Now we have no evidence the crew did anything wrong," he said. "And in fact, now, we should be operating with the primary assumption being that something bad happened to that plane shortly after they said good night."
If a crisis on board caused the plane to lose pressure, he said, pilots could have chosen to deliberately fly lower.
"It's called a high dive, and you go as quickly as you can down that to that altitude," he said.
As speculation over what led to the flight's disappearance showed no signs of slowing, investigators appeared to be beefing up their efforts to comb the southern Indian Ocean.
Buoyed by a third set of satellite data that indicated possible debris from the plane in the water, the international team led by Australia fought bad weather as it looked for signs of the Boeing 777 and the 239 people who were aboard when the plane went missing on March 8.
Four more jets -- two from China and two from Japan -- are set to join the reconnaissance team on Monday, authorities said.
France's Foreign Ministry said Sunday that radar data from a satellite pointed to floating debris in the Indian Ocean 2,300 kilometers (1,430 miles) from Perth, Australia. The data were immediately passed along to Malaysian authorities, and French satellite resources will home in more on the area, the ministry said.
Satellite images previously issued by Australian and Chinese authorities have also captured possible large floating objects, stoking hopes searchers may find debris from the missing plane.
But so far, searchers have turned up empty-handed after more than two weeks of scouring land and sea.
Eight aircraft and one ship conducted Sunday's search, and there were no sightings of significance, the Australian Maritime Safety Authority said.
On Saturday, searchers found a wooden pallet as well as strapping belts, AMSA's John Young said. The use of wooden pallets is common in the airline industry.
"It's a possible lead ... but pallets are used in the shipping industry as well," he said Sunday. Authorities have said random debris is often found in the ocean.
The Sunday search was split into two areas that cover 59,000 square kilometers (23,000 square miles), about 2,500 kilometers (1,550 miles) southwest of Perth.
The flying distance to and from the search area presents a big challenge for search aircraft. "They're operating at the limits of their endurance," Barton said. The distance is forcing teams to spread the search out over multiple days.
Only one ship, an Australian naval vessel called HMAS Success, was involved in the Sunday search, Barton said. A Norwegian merchant ship previously involved was released in anticipation of rough weather.
Was turn reprogrammed?
Malaysian officials, in a written update Sunday on the search, cast doubt on the theory that someone, perhaps a pilot, had reprogrammed the aircraft to make an unexpected left turn during the flight.
"The last ACARS transmission, sent at 1:07 a.m., showed nothing unusual. The 1:07 a.m. transmission showed a normal routing all the way to Beijing," it read.
The Aircraft Communications Addressing and Reporting System measures thousands of data points and sends the information via satellite to the airline, the engine manufacturer and other authorized parties, according to CNN aviation and airline correspondent Richard Quest.
Had the plane been reprogrammed to change course, the ACARS system should have reported it during its last communication at 1:07. The ACARS is supposed to report new information every 30 minutes, but it was silent at 1:37.
"It is important because it is more consistent (with an emergency). In other words, if the pilots had put in this waypoint that they were going to turn to and that they knew in advance of their last communication that they were going to turn, then everyone was (saying) that this had to be a premeditated act," said Mary Schiavo, a CNN aviation analyst and a former inspector general of the U.S. Department of Transportation. "Now if this information is correct, and it was not premeditated, then it does fit very closely with the scenario that, whatever happened, happened suddenly and they turned perhaps to go back to an emergency airport."
Hope, only hope
Australian Prime Minister Tony Abbott voiced hope that investigators could be closing in on an answer to questions that have dogged authorities for days: What happened to the plane, and where is it?
"We have now had a number of very credible leads, and there is increasing hope -- no more than hope, no more than hope -- that we might be on the road to discovering what did happen to this ill-fated aircraft," Abbott said at a news conference.
In one of the great aviation mysteries in history, the airliner carrying 239 people disappeared March 8 after it took off from Kuala Lumpur, Malaysia, on a flight to Beijing. An exhaustive search covering 2.97 million square miles -- nearly the size of the continental United States -- has yielded some clues but no evidence of where the Boeing 777 is or what happened to it.
NASA satellites to be employed
A U.S. Navy P-8 Poseidon, one of the military's most sophisticated reconnaissance planes, on Sunday refocused on an area highlighted in Chinese satellite images of a large object floating in the southern Indian Ocean. The object the Chinese satellite photographed is estimated to be 22.5 meters long and 13 meters wide (74 feet by 43 feet), officials said.
The plane was forced to fly at an altitude of just 300 feet because of low cloud ceilings and poor visibility.
Conditions were terrible, said Lt. Cmdr. Adam Schantz, the officer in charge of P-8 operations in Perth.
The space agency said it will check the archives of satellite data and use space-based assets such as the Earth-Observing-1 satellite and the ISERV camera on the International Space Station to scour for possible crash sites. The resolution of these images could be used to identify objects of about 98 feet (30 meters) or larger.
The floating object reported in the Chinese satellite images was about 77 miles from where earlier satellite images issued by Australia spotted floating debris.
Countries from central Asia to Australia are also engaged in the search along an arc drawn by authorities based on satellite pings received from the plane hours after it vanished.
One arc tracks the southern Indian Ocean zone that's the focus of current attention. The other arc tracks over parts of Cambodia, Laos, China and into Kazakhstan.