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Air France Crash Remains a Mystery

A sleek tail fin found floating in the Atlantic Ocean. The few battered remnants of the jet that floated away before it sank. Fifty bodies found in a 100-mile swath of sea. And a batch of computer messages.

These are the primary clues that some of the world's foremost detectives - aviation accident investigators with the French Bureau d'EnquĂȘtes et d'Analyses (BEA) - are combing through in hopes of learning why Air France Flight 447 disappeared June 1, killing 228 people.

The clues provide a remarkable amount of information about the Airbus A330's final minutes, but investigators caution that they are far from determining the actual cause of the disaster or piecing together a detailed account of what went wrong.

Those details may never be known unless the plane's two "black box" recorders can be located in a section of the Atlantic Ocean that is mountainous and more than 10,000 feet deep.

The hunt for the flight recorders is a detective effort every bit as complex and sophisticated as the accident investigation, say undersea experts.

"Rarely is it like finding the smoking gun," said Kevin Darcy, a consultant who formerly served as Boeing's accident investigation chief.

"It's more like police work in general, where there's a lot of mundane stuff that you go through and among that a pattern starts to emerge," he said.

Based on reviews of previous accident cases, interviews with experts who have investigated other crashes and a 70-page preliminary report issued this month by French investigators, here is what is known about the hunt for the cause of the Flight 447 disaster.

Physical evidence

Very little of the Air France A330 has been found, but several pieces of wreckage offer clues, according to the French BEA.

An examination of the tail fin, which rises vertically from the fuselage, shows that it was torn forward from its moorings, the BEA said. That suggests that it came loose when the jet stopped suddenly. As a result, French investigators suspect that the jet was intact when it hit the water and that the impact tore off the tail.

Several other items found floating in the ocean suggest that the jet's belly struck the water with great downward force, the BEA said.

A rack used to hold meals in the galley was found with the shelving and trays smashed to the bottom. A room used by pilots to rest during long flights was recovered, and its floor was bent upward, suggesting "a strong upward pressure from below," the French investigative agency said.

French investigators have not yet had access to autopsies of the 50 bodies pulled from the ocean, but the 30 found by the French navy were clothed. That also provides evidence that they were not flung out of the plane in a high-speed breakup.

Brazilian officials, however, have suggested that some of the bodies they recovered were not clothed.

None of the wreckage shows signs of an explosion.

Computer data

The A330 was equipped with a computerized sensor that automatically sent reports via satellite to an Air France maintenance facility.

Starting at 2:10 a.m. on June 1, just minutes before the crash, the plane sent a string of messages reporting problems triggered by the failure of speed sensors.

Erroneous speed readings can be caused by ice forming in the sensors, known as Pitot tubes. Several crashes occurred when pilots were confused by incorrect readings.

Undersea search

Even though ships have prowled the Atlantic in vain for several weeks in search of the jet's two crash-proof recorders, chances are still good that the recorders and the wreckage will be found, according to investigators and deep water salvage experts.

John Fish, a sonar expert who has helped recover underwater aircraft wreckage, said he's optimistic that a thorough search of the ocean bottom will help uncover the jet's remains.

"They are going to find it," Fish said. "It's just going to take longer because it is in deeper water."

The search is similar to what occurred after a South African Airways jet crashed in the Indian Ocean on Nov. 28, 1987, Fish said. Initial attempts to listen for the pingers on the recorders, which were nearly 15,000 feet deep, were futile.

But a U.S. team using sonar located the wreckage two months later. More than a year after the accident, one of the two recorders was found. The cockpit recording confirmed that the jet had been brought down by a fire.

Finding the cause

So far, the clues indicate that the Air France jet's problems began with the failure of the speed sensors.

Even if no more clues surface, that may be enough to make some basic assumptions about why the plane crashed and to prevent it from happening again, Massachusetts Institute of Technology aeronautics professor John Hansman said.

Even so, investigators are never satisfied without more concrete information.

Besides, said Darcy, a plodding search for the truth not only reassures the public, but also helps make aviation safer.

"There's almost always a wealth of information that comes out from a thorough investigation that not only helps you figure out how to prevent that accident, but other accidents as well that share the same links," he said.

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