Posted 06/10/09 at 05:08:24 PM by Mark Edward Soper

Could the design philosophy used by Airbus's fly-by-wire electronic flight control systems have been the final death blow to Air France Flight 447? That's the chilling possibility suggested by a recent posting by Information Week blogger Michael Hickins.

Air France Flight 447 used an Airbus A330, which uses a completely electronic fly-by-wire system without manual or hydraulic backups. The leading theory of the cause of the Air France Flight 447 crash is conflicting information from pitot tubes, which are used to transmit flight and wind speed information to onboard computers. While Airbus had begun to replace pitot tubes in May, the pitot tubes had not yet been replaced on the plane that crashed in the Atlantic.

According to a report cited by Hickins, Airbus and Boeing, the biggest rivals in the commercial jet field, have diametrically opposed views on pilot override capabilities. Airbus A320 and newer models include so-called "hard limits" that prevent maneuvers that would overstress the airframe, while Boeing's approach keeps the pilot in charge. While it's impossible to know if a Boeing-style system could have enabled the flight crew of Air France Flight 447 to successfully handle the severe weather existing in the air, some Boeing aircraft have survived stresses well in excess of recommended limits - limits that could not be exceeded if the flight computers are in ultimate charge of the aircraft. Commercial pilots' comments, like the industry itself, are divided over whether the differences in fly-by-wire design make one method ultimately safer than another.

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