Airplanes no longer require pilots to manually control fuel flow. Whether it’s a small light aircraft or a jumbo-sized commercial jet, it will likely feature autothrottle. Located in the cockpit, autothrottle simplifies many fuel-based controls. What is autothrottle exactly, and how does it work?
Overview of Autothrottle
Autothrottle is a feature of many modern aircraft that controls engine thrust. As pilots set the airplane’s speed, the thrust level of the airplane’s engine or engines will change accordingly.
Along with lift, weight and drag, thrust is one of the four forces of flight. Thrust specifically refers to the mechanical force engines produce to propel the aircraft through the air. Most airplanes are powered by gas engines, such as turbofans, that burn a mixture of fuel and air. The combustion process of these gas engines produces hot exhaust gases that shoot out of the back of the engines. With autothrottle, pilots can
How Autothrottle Works
There are different types of autothrottle systems, but most of them support both automatic and manual operation. It may work automatically in conjunction with the airplane’s autopilot mode, or it may support manual operation by the pilots. Manual operation essentially allows pilots to override the autothrottle.
Autothrottle also has two different modes: speed and thrust. Speed mode is designed to maintain a set speed. Pilots can specify a speed. Once set, the airplane’s autothrottle will adjust the fuel flow accordingly to maintain this speed.
Thrust mode is an alternative mode that’s designed to maintain a power setting based on various flight phases. Some of these flight phases include takeoff, climb and descent. During the takeoff phase, the autothrottle will maintain sufficient power for the airplane to take off. During the climb phase, the autothrottle will provide enough power for the airplane to climb. During the descent phase, the autothrottle will remain in idle position.
Some of the benefits of autothrottle include the following:
- Improved fuel efficiency
- Reduced pilot workload
- Precision
Autothrottle vs Autothrust: What’s the Difference?
You may come across the terms “autothrottle” and “autothrust.” They both refer to the same thrust-controlling feature.
Boeing uses the term “autothrottle” for its airplane. Airbus, on the other hand, uses the term “autothrust.” There are other nuances between these systems, but the terms “autothrottle” and “autothrust” refer to the same thrust-controlling feature of modern airplanes. Boeing simply prefers the term “autothrottle,” whereas Airbus prefers the term “autothrust.”
