Military planes and ships located more debris from an Air France jet on Wednesday, but rough seas and strong winds were slowing the recovery effort and delaying the arrival of crucial deep-water submersibles.
Search vessels from several nations pushed toward the floating debris, including a 23-foot chunk of plane and a 12-mile-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 — including three Americans — from Rio de Janeiro to Paris, Air Force spokesman Col. Jorge Amaral said.
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 miles 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.
French and Brazilian officials had already announced 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, and was confirmed to The Associated Press by an aviation industry official with knowledge of the investigation.
The burst of automatic messages sent from the jetliner before it disappeared with 228 people on board suggests it probably broke apart in the skies and fell to the ocean in pieces, said the official, who isn't authorized to discuss details of the probe publicly.
The pilot sent a manual signal at 11 p.m. local time saying he was flying through an area of "CBs" — black, electrically charged cumulonimbus clouds that come with violent winds and lightning.
Satellite data has shown that towering thunderheads were sending 100 mph updraft winds into the jet's flight path just then.
Ten minutes later, a cascade of problems began: Automatic messages indicate the autopilot had disengaged, a key computer system had switched to alternative power, and controls needed to keep the plane stable had been damaged. An alarm sounded indicating the deterioration of flight systems.
Three minutes after that, more automatic messages reported the failure of systems to monitor air speed, altitude and direction. Control of the main flight computer and wing spoilers failed as well.
The last automatic message, at 11:14 p.m., indicated loss of cabin pressure and complete electrical failure — catastrophic events in a plane that was likely already plunging toward the ocean.
"This clearly looks like the story of the airplane coming apart," the airline industry official told the AP. "We just don't know why it did, but that is what the investigation will show."
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 Defense 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 defense minister and the Pentagon have said there were no signs that terrorism was involved, and Jobim said "that possibility hasn't even been considered."
Meanwhile, authorities are investigating reports that a similar Air France flight from Buenos Aires to Paris after the airline received a bomb threat over the phone.
Police and officials at Buenos Aires' Ezeiza Airport spent 90 minutes inspecting the threatened plane for explosives on the evening of May 27, but found nothing, according to a Brazilian news report.
During the search, passengers were not evacuated from the jet and later arrived safely at their destination in Paris.
The planes stepped up overflights 400 miles northeast of the Fernando de Noronha islands off Brazil's northern coast, where an airplane seat, a fuel slick and pieces of white debris were spotted Tuesday in the vast ocean.
Rescue boats from several nations were sailing toward the site to start the recovery.
The reason for the crash remains unclear, with fierce thunderstorms, lightning or a catastrophic combination of causes as possible theories.
Brazilian Defense Minister Nelson Jobim told reporters in Rio that no bodies had been found and there was no signs of life.
If no survivors are found, it would be the deadliest crash in Air France's history, and the world's worst civil aviation disaster since the November 2001 crash of an American Airlines jetliner in the New York City borough of Queens that killed 265 people.
In Paris on Wednesday, Prazuck said the French military was moving away from its sweeping aerial searches to "the next phase, the recovery of this debris, to be able to conduct the investigation and determine the probable zone of the accident, around which we must search for the black boxes."
Remotely controlled submersible crafts will have to be used to recover wreckage settling so far beneath the ocean's surface. France dispatched a research ship equipped with unmanned submarines that can explore as deeply as 19,600 feet.
A U.S. Navy P-3C Orion surveillance plane — which can fly low over the ocean for 12 hours at a time and has radar and sonar designed to track submarines underwater — and a French AWACS radar plane were joining the operation.
Even at great underwater pressure, the black boxes "can survive indefinitely almost," said Bill Voss, president and CEO of the Flight Safety Foundation in Alexandria, Virginia. "They're very rugged and sophisticated, virtually indestructible."
Weather and aviation experts are focusing on the possibility of a collision with a brutal storm that sent winds of 100 mph straight into the airliner's path.
Towering Atlantic storms are common this time of year near the equator — an area known as the intertropical convergence zone. But several veteran pilots said it was extremely unlikely that Flight 447's crew intended to punch through a killer storm.
Since thunderstorms can rise to more than 60,000 feet high, where passenger planes cannot climb over them, pilots will often weave left and right to find a route that avoids the worst of the weather.
"Nobody in their right mind would ever go through a thunderstorm," said Tim Meldahl, a captain for a major U.S. airline who has flown internationally for 26 years. "If they were trying to lace their way in and out of these things, they could have been caught by an updraft."
The crew made no distress call before the crash, but the plane's system sent an automatic message just before it disappeared, reporting lost cabin pressure and electrical failure.
Brazilian officials described a three-mile strip of wreckage. Jack Casey, an aviation safety consultant in Washington, D.C., and former accident investigator, said that it could indicate the Air France jetliner came apart before it hit the water.
On land, hundreds of relatives grieved deeply for those who were lost, a roster that included vacationers, business people, even an 11-year-old boy traveling alone back to school in England.
"We will miss your dancing feet," read a tribute from the Northern Ireland family of Eithne Walls, 29, a dancer-turned-doctor. "We will miss your silliness, your wit and your hugs. We will always hold you in our hearts and you are never truly gone."
The Associated Press contributed to this report.