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Missing plane baffles aviation experts

With a good safety record and robust backup systems, the Airbus 330 wouldn't be easily downed by lightning, they say.

By Staff writer of The Christian Science Monitor / June 1, 2009



New York

As media speculation centers on lightning and air turbulence as possible causes of the disappearance of an Air France flight from Rio de Janeiro to Paris, many aviation analysts are puzzled by the circumstances of the missing plane.

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The plane, a twin-engine Airbus A330-200, took off from Galeão Airport at 7:30 p.m. local time with 228 people on board. It was last heard from three hours later when it radioed to say it would enter Senegalese air space within the hour, according to a statement from Aeronautica, which is in charge of Brazilian air space.

At that point, the plane was flying "normally" at 35,000 feet. About a half hour later, Air France says the plane sent out an automatic message reporting "a loss of pressure and failures of the electrical system." Then silence.

The Airbus A330 has an excellent safety record – in fact, it's never been involved in a fatal commercial crash. One reason is the way it's designed: It has multiple redundancies that kick in if there's an electrical or any other kind of failure. And with authorities in France ruling out terrorism or a hijacking, many analysts say they are baffled by the plane's disappearance.

"These planes go through turbulence all the time and they do get hit by lightning – while it may startle the passengers it's not something that should create a problem that would cause a jet to stop flying. They're designed so things can fail and the plane can continue to fly without any problems," says Clint Oster, an aviation analyst at Indiana University in Bloomington.

"It's not adding up right now. There clearly has to be something else going on – some unusual circumstance we don't know yet."

What Airbus's backups do

The Airbus A330 is a "fly by wire" jet, which means the flight controls are not moved by pulleys and cables but are electrically controlled and hydraulically activated, according to an A330 pilot who is not authorized to speak to the press. As a result, it is more difficult to fly when it shifts into an emergency mode.

"I wouldn't want to be in emergency electrical configuration and in severe turbulence, but it is controllable – you can fly," says the pilot. "But if they lost all hydraulics for some reason, again highly, highly unlikely due to the design of the A330, then they would not be able to remain airborne. You can't fly without hydraulics."

The A330 has several backup electrical systems that are supposed to run the hydraulics. Those backups are also designed to ensure there's still some kind of radio contact that could be used to send out a Mayday call. The fact that the plane was able to send out an automatic message indicating the electrical failure has some analysts puzzled as to why there was no communication from the pilots themselves.

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