In avionics, what does the term 'autopilot' refer to?

The term 'autopilot' in avionics specifically refers to a system that automatically controls the trajectory of an aircraft. This system allows the aircraft to fly without direct control by the pilot for significant portions of the flight, thereby reducing pilot workload and enhancing the efficiency and safety of flight operations.

Autopilot systems can manage various aspects of flight, including altitude, speed, and course, allowing the aircraft to maintain a specific flight path without continuous manual input. This technology is critical for long-haul flights where maintaining precise control over extended periods can be challenging for human pilots.

The other options describe functions or devices that are not aligned with the primary definition of autopilot. A device for manual flight control does not fall under the scope of autopilot since it implies the opposite—active, manual control by the pilot. A communication tool for pilots refers to systems like radio equipment used for voice communication, which is unrelated to the control of the aircraft’s flight path. Lastly, a backup navigation system pertains to instruments that provide navigational data but does not encompass the primary function of automatically controlling an aircraft’s trajectory.