FERNANDO DE NORONHA, Brazil - Military planes located more debris from an Air France jet on Wednesday as the first navy ship arrived at the scene in the mid-Atlantic. But high seas and heavy winds slowed the recovery effort and delayed the arrival of crucial deep-water submersibles.

Search vessels from several countries pushed toward the floating debris, including a seven-metre chunk of plane and a 20-kilometre-long oil slick that Brazilian pilots spotted from the air. Rescuers have still found no signs of life from the plane that was carrying 228 people from Rio de Janeiro to Paris, air force spokesman Col. Jorge Amaral said.

A Brazilian navy spokeswoman said a patrol boat was close to one debris field after spending two days pushing through rough weather to reach the site, but had not yet retrieved any wreckage.

A navy frigate was expected to arrive later in the day, said the spokeswoman, who spoke on condition of anonymity in keeping with policy.

Flight 447 disappeared minutes after flying into an extremely dangerous band of storms Sunday night, but what exactly caused its electrical systems and cabin pressure to fail remains a mystery. The "black box" cockpit recorders could be kilometres below the surface of the Atlantic Ocean.

If they can't be recovered, investigators will have to focus on maintenance records and a burst of messages sent by the plane just before it disappeared. Officials have released some details of these messages, but a more complete chronology was published Wednesday by Brazil's O Estado de S. Paulo newspaper, citing an unidentified Air France source.

Air France and Brazilian military officials refused to confirm the report. But if accurate, it suggests that Flight 447 may have broken up while in the air as it passed through a violent storm, experts told The Associated Press.

The report said the pilot sent a manual signal at 11 p.m. local time saying he was flying through an area of "CBs" - black, electrically charged cumulo-nimbus clouds that come with violent winds and lightning. Satellite data has shown that towering thunderheads were sending 160 km/h updrafts into the jet's flight path at that time.

Ten minutes later, the plane sent a burst of automatic messages, indicating the autopilot had disengaged, the "fly-by-wire" computer system had been switched to alternative power, and controls needed to keep the plane stable had been damaged. An alarm also sounded, indicating the deterioration of flight systems, according to the report.

Three minutes after that, more automatic messages indicated the failure of two other fundamental systems pilots use to monitor air speed, altitude and direction. Then, a cascade of other electrical failures in systems that control the main flight computer and wing spoilers.

The report repeats a detail previously released by Brazil's Air Force: that the last message came at 11:14 p.m., indicating loss of air pressure and electrical failure. The newspaper said this could mean sudden de-pressurization, or that the plane was already plunging into the ocean.

Air France spokesman Nicolas Petteau referring questions about the report to the French accident investigation agency, BEA, whose spokesman Martine Del Bono said the agency won't comment.

Brazil's Defence Minister Nelson Jobim also declined to comment on the report, saying "that investigation is being done by France, Brazil's only responsibility is to find and pick up the pieces."

France's defence minister and the Pentagon have said there were no signs that terrorism was involved, and Jobim said "that possibility hasn't even been considered."

The fierce thunderstorms, turbulence, lightning or a catastrophic combination of events could have broken apart the plane, aviation experts have said. And while the messages reported by the newspaper don't indicate why the aircraft went down, they strongly suggest it broke apart in the air, said Bill Voss, president and CEO of the Flight Safety Foundation in Alexandria, Va.

"These are telling us the story of the crash. They are not explaining what happened to cause the crash," Voss said. "This is the documentation of the seconds when control was lost and the aircraft started to break up in air."

Voss stressed that the messages alone were not enough to understand why the Air France jet went down, noting that the black boxes will have "far more parameters" that could determine the cause.

The new debris was discovered about 90 kilometres south of where searchers a day earlier found an airplane seat, a fuel slick, an orange buoy and pieces of white debris. The original debris was found roughly 640 kilometres northeast of the Fernando de Noronha islands off Brazil's northern coast, an area where the ocean floor drops as low as 7,000 metres below sea level.

Brazil was leading the search, while France took charge of the crash investigation, working with Air France, Airbus and meteorologists to determine what happened.

Brazilian divers were expected to arrive Thursday, but if the black boxes are at the bottom of the sea, their recovery will have to wait for the arrival early next week of a French research ship with remotely controlled submersibles that can explore as deeply as 6,000 metres.

The sturdy black boxes - voice and data recorders - are built to give off signals for at least 30 days, even underwater, and could keep their contents indefinitely.

But the head of France's accident investigation agency, Paul-Louis Arslanian, said in Paris that he is "not optimistic" about recovering the recorders - and that investigators should be prepared to continue the probe without them.

"It is not only deep, it is also mountainous," he said. "We might find ourselves blocked at some point by the lack of material elements."

A French AWACS radar plane and two other French military planes flew Wednesday over the area where debris was found to better narrow down the search zone. A U.S. navy P-3C Orion surveillance plane - which can fly low over the ocean for 12 hours at a time - also joined the operation.

Arslanian said investigators didn't have enough information to determine whether the plane broke up in the air or upon impact with the sea, and that in the absence of black box data, they are studying maintenance and other records.

"For the moment, there is no sign that would lead us to believe that the aircraft had a problem before it took off," Arslanian said.

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