Automatic Flight Control Systems and Their Effect on Aircraft

Have you been curious about autothrottles and what they do? To most, probably not since a few years ago, fully integrated automatic flight control systems with autothrottle were exclusively for transport aircraft and heavy iron business jets. However, AFCS with AT are recently being included on single engine turboprops, and soon even piston aircraft! So, to those uninitiated, here’s a simple breakdown on what exactly AFCS with autothrottle is, and why it can be beneficial for pilots.

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Some may be skeptical about the inclusions of automation, thinking that it would reduce the amount of control a pilot has over their aircraft. This is untrue, the main purpose of cockpit automation is to reduce physical workload and improve the safety of flight. It essentially provides extra assistance to the actions you’re already doing, as well as make things more relaxed for the pilot in general. Autothrottle reduces the need for using a lot of controllers, while seamlessly integrating itself naturally onto the controls. The system still makes clear what is controlling what, but there is less management requirements on the pilot’s end. The main control option at most is either engaging or disengaging, as well as controlling the airspeed you want.

While it sounds extremely simple, it has its limitations due to ensuring that most engine and aircraft configurations are handled by automation. For instance, there are many modes to choose from when using flight director or autopilot. With autothrottle, most only feature two modes, which is speed and power, and occasionally some that features hold mode. It’s also limited by what is determined by the flight director, and while you can have the autothrottle take control over the flight director/autopilot, you can’t use both at the same time. It has logic when determining whether the flight director/autopilot is controlling speed or power, and it will control the other. For example, if FD/AP is controlling power, then autothrottle will control speed and vice versa.

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There are many other aspects to consider when utilizing autothrottle, such as how it handles takeoffs and whether an FD/AP mode is selected during the process. Also, how it handles the initial climb, when choosing FLC or VS and how autothrottle will utilize climb power. Cruise, descent, and landing are also handled differently, with its own unique conditionals from switching between FD/AP, FLC, airspeed, and autothrottle. In case something goes wrong as well, compared to autopilot, most autothrottles have simple override clutches that can be used without disengaging, and when the pilot wants to return to using the system, it will revert back to its previous state.

There are many automatic flight control systems with autothrottle out there that have minor use-case differences, so be on the lookout and research what would be best for your piloting style. Out of everything in avionics, autothrottle requires the least amount of study to understand it. While looking into that, make sure that you also investigate the best aircraft to go along with your AFCS – AT here with Norfolk Aviation! Have something in mind already? Or maybe you’re looking to sell or customize instead? Give us a call, or contact us, and we will help you ease your way into soaring to new heights!

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