Automatic throttle control for business and commuter aircraft

Honeywell has developed a digital autothrottle system for application on the Gulfstream IV business jet. This is the first true full-authority digital autothrottle designed specifically for the business and commuter market. A system description of the Gulfstream IV autothrottle is presented, and attention is given to modes and functions, design tradeoffs, and resulting performance. The autothrottle´s modes are: takeoff, go around, flight level change, and speed hold. The primary design tradeoff during development was throttle activity versus control accuracy and dynamic response. The Honeywell design includes several techniques to yield the required accuracy with smooth response and minimal throttle activity. The result is an autothrottle system appropriate for business jets (where passenger comfort is very important). Some of the special considerations involved in designing a digital autothrottle system for use with FADEC (full authority digital engine controls)-controlled engines are discussed