A debris field scattered across three miles (five kilometers) of open water marks the spot in the Atlantic Ocean where an Air France Airbus A330-200 went down with 228 people on board.

But until the plane's all-important black box recorders are recovered from the depths of the Atlantic, just what caused Sunday's mishap and doomed Flight 447 will continue to haunt all of those concerned.

Terrorist attack not excluded

The reason for the crash remains unclear, with strong thunderstorms, lightning or a catastrophic combination of causes as possible theories.

Considering the precedent of the Sept. 11, 2001, attacks in America, too, many people mentioned the possibility of a terrorist hijacking when the plane initially was reported lost.

Jean-Louis Borloo, the French minister overseeing transportation, firmly excluded terrorism and said he believed the disappearance to be purely an aviation accident.

An anonymous official from French Defense Ministry also said that there was no evidence indicating an attack or any violence on the plane.

Still, French Defense Minister Herve Morin said terrorism could not be discounted.

"We can't rule out a terrorist act since terrorism is the main threat to Western democracies," Morin told Europe 1 radio. "But at this time we don't have any element whatsoever indicating that such an act could have caused this accident."

The mysterious accident left such a mist that the French government kept an very prudent attitude.

"No hypothesis" could be excluded, French President Nicolas Sarkozy said Monday at Charles de Gaulle Airport in Paris.

Trace of black boxes

Brazilian officials said the plane disappeared over the Atlantic somewhere between a point 186 miles (300 kilometers) northeast of their coastal city Natal and the Cape Verde islands off Africa.

The region is known as the "horse latitudes," where the tropics of the Northern and Southern Hemispheres mix, sometimes creating brutal thunderstorms that can rise to 55,000 feet (16,760 meters), higher than commercial jetliners can go.

On Wednesday, Brazilian military planes spotted a five-kilometer path of debris on the Atlantic about 400 miles (644 kilometers) from Brazil's Fernando de Noronha archipelago, near the Sao Pedro and Sao Paulo Islands.

Douglas Ferreira Machado, head of investigations for Brazil's Civil Aeronautics Agency, told reporters "the black boxes should have sank in the sea."

The cause of the accident will not be known until the black boxes are recovered. They are designed to last 30 days underwater

Key factors to crash

What caused the accident? Experts are at a loss to explain the crash.

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.

Pierre Sparaco, an French aviation expert, analyzed the flight records of Flight 447 and pointed out Tuesday that technological flaws blamed on bad weather could be the most likely reason.

He noted that the plane went down while it was cruising, the part of a flight that is much safer than the takeoff or landing.

Air France chief executive officer Pierre-Henry Gourgeon thought otherwise. He said the true reason likely was that certain technological failures occurred before the plane encountered the massive storm.

Alain Bouillard, who led the probe into the crash of the Concorde in July 2000, was put in charge of France's accident investigation team. Bouillard said the team would submit its first preliminary report by the end of June.

(Xinhua News Agency June 4, 2009)