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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. The FC could move the controls faster than a pilot’s mind could react. Not only could it fly the stati-cally unstable airplane perfectly well, it could do a lot of other things, such as smoothing out the effects of configuration changes and protecting the airplane from exceeding limitations such as load factor and AOA limits. The latter was big for the military. Prior to FBW they lost many fighters in 94 PROFESSIONAL PILOT / September 2004 combat when their pilots pulled through the AOA limit in the heat of battle and the aircraft departed into an unrecoverable spin. Soon the civilian world saw advantages to FBW too—specifical-ly safety and ease of control. With built-in “hard limits” an FBW-equipped aircraft cannot be stalled or over-G’d. Just as important, it’s easier to fly, freeing the pilot’s attention for higher-order tasks. Airbus Industrie, followed by Boeing, chose FBW for its new air-liners. Fly-by-wire is not a simple tech-nology, nor is it without hazard. In fact, it has the potential for new kinds of accidents—for example, certain combinations of control sys-tem lag (measured in fractions of a second) and actuator rate limits (how fast a control surface can be moved) can allow aircraft-pilot coupling events, similar to PIOs, that have caused loss of control, such as the Aug 1993 crash of a Saab Gripen in Sweden. In FBW systems, multiple compu-tation channels are required for safety in case of failure. Multiple channels monitor each other and/or “vote.” This is a highly complex communication task, and Boeing struggled with this aspect of the 777’s FBW until late in its develop-ment program.
Flying the Falcon 7X |
