Autopsies have revealed fractures in the legs, hips and arms of Air France Flight 447 victims, injuries that — along with the large pieces of wreckage pulled from the Atlantic — strongly suggest the plane broke up in the air, experts say.

The president of France's Senate said Thursday he was sure that friction between experts from his country and Brazil will soon be resolved and assured victims they would be indemnified.

With more than 400 pieces of debris recovered from the ocean's surface, the top French investigator expressed optimism about determining what brought down the plane on May 31. But he also called the search conditions — far from land in very deep water — "one of the worst situations ever known in an accident investigation."

Click here for photos.

Click here for FOXNews.com's plane crash content center.

French investigators are beginning to form "an image that is progressively less fuzzy," Paul-Louis Arslanian, who runs the French air accident investigation agency BEA, told a news conference Wednesday outside Paris.

"We can say there is a little less uncertainty, so there is a little more optimism," he said. But "it is premature for the time being to say what happened."

A spokesman for Brazilian medical examiners told The Associated Press on Wednesday that autopsies revealed fractures on an undisclosed number of the 50 bodies recovered so far. The official spoke on condition he not be named due to department rules.

"Typically, if you see intact bodies and multiple fractures — arm, leg, hip fractures — it's a good indicator of a midflight break up," said Frank Ciacco, a former forensic expert at the U.S. National Transportation Safety Board. "Especially if you're seeing large pieces of aircraft as well."

The pattern of fractures was first reported Wednesday by Brazil's O Estado de S. Paulo newspaper, which cited unnamed investigators. The paper also reported that some victims were found with little or no clothing, and had no signs of burns.

"In an in-air break up like we are supposing here, the clothes are just torn away," said Jack Casey, an aviation safety consultant in Washington, D.C. and a former accident investigator.

Casey also said multiple fractures are consistent with a midair breakup of the plane, which was cruising at about 34,500 feet when it went down.

"Getting ejected into that kind of windstream is like hitting a brick wall — even if they stay in their seats, it is a crushing effect," Casey said.

When a jet crashes into water mostly intact — such as the Egypt Air plane that hit the Atlantic Ocean after taking off from New York in 1999 — debris and bodies are generally broken into small pieces, Ciacco said.

Lack of burn evidence would not necessarily rule out an explosion, said John Goglia, a former member of the U.S. National Transportation Safety Board.

On Thursday the president of France's Senate, Gerard Larcher, told reporters in Brazil that he was sure that complaints about restricted French access to autopsies of victims is "a question that will be rapidly solved locally."

Arslanian said Wednesday that Brazilian authorities had not allowed a French doctor from the BEA to participate in autopsies on some Flight 447 bodies, though he said French judicial authorities were present.

Larcher also said he was sure that Air France "will respect all the necessary procedures involved in indemnities" for victims.

Searchers from Brazil, France, the United States and other countries are methodically scanning the surface and depths of the Atlantic for signs of the Airbus A330 that crashed after running into thunderstorms en route from Rio de Janeiro to Paris. All 228 people aboard were killed.

Still missing are the plane's flight data and voice recorders, thought to be deep under water.

French-chartered ships are trolling a search area with a radius of 50 miles, pulling U.S. Navy underwater listening devices attached to 19,700 feet of cable. The black boxes send out an electronic tapping sound that can be heard up to 1.25 miles away.

Without the black boxes to help explain what went wrong, the investigation has focused on a flurry of automated messages sent by the plane minutes before it lost contact; one suggests external speed sensors had iced over, destabilizing the plane's control systems.

Arslanian said most of the messages appear to be "linked to this loss of validity of speed information." He said when the speed information became "incoherent" it affected other systems on the plane.

The automated messages were not alarm calls and no distress call was picked up from the plane, he said.

Air France has replaced the sensors, called Pitot tubes, on all its A330 and A340 aircraft, under pressure from pilots who feared a link to the accident.