Unlike Airbus, Boeing lets aviator override fly-by-wire technology
Monday, March 20, 2000
By JAMES WALLACE
SEATTLE POST-INTELLIGENCER REPORTER
MIAMI — As the Airbus A320 jetliner descended through 3,000 feet on its final approach to the airport, co-pilot Rudy Canto glanced off to the right and spotted a regional jetliner bearing down on the Airbus plane.
The regional jet also was descending, and the two planes were seconds away from a midair collision.
Canto barked a warning and the pilot immediately pushed the side-stick controller hard left and pulled back as far as it would go and held it there — anabrupt maneuver that should have resulted in the plane’s losing lift and stalling.
But one of seven flight-control computers on the A320 took over and the Airbus plane climbed sharply and turned away from the regional jet just in time to avoid a collision.
No report was filed on the near midair collision. The flight was actually a demonstration for a group of journalists earlier this month in one of the $12 million A320 flight simulators at the new Airbus Industrie training center in Miami.
What happened in the simulator, though, was no different from what would have occurred in the sky. And it is at the heart of an ongoing debate in aviation today:
Should pilots or a computer have the ultimate control authority over a commercial jetliner as the plane approaches its design limits in an emergency?
Airline passengers can’t see it, but this is the most significant difference between Boeing and Airbus planes.
Dramatic advancements in technology have made it possible for planes built by either manufacturer to be flown by computers from shortly after takeoff through the landing.
But Airbus has taken a much different philosophical approach to using computers than its rival. The European airplane maker designed its new fly-bywire jets such as the A320 with built-in hard limits, or “protections.”
The Boeing Co., on the other hand, believes pilots should have the ultimate say. On Boeing jets, the pilot can override onboard computers and their built-in soft limits.
“It’s not a lack of trust in technology,” said John Cashman, director of flightcrew operations for Boeing. “We certainly don’t have the feeling that we do not want to rely on technology. But the pilot in control of the aircraft should have the ultimate authority.”
On all Airbus planes other than the older A300 and A310, computers prevent the pilot from putting the plane into a climb of more than 30 degrees where it might lose lift and stall. The maximum bank or roll allowed is 67 degrees. The plane’s nose-down pitch is limited to 15 degrees. There are protections against overspeed.
And the computer won’t allow the plane to make any extreme maneuvers that would exceed 2.5 times the force of gravity.