What is the primary purpose of the FMS autopilot mode?

The primary purpose of the Flight Management System (FMS) autopilot mode is to aid in navigation and reduce pilot workload during flight. The FMS integrates various navigation and performance data to facilitate the management of the flight path. By automating certain tasks, such as waypoint navigation, altitude and speed management, and lateral and vertical guidance, the FMS allows pilots to focus on other critical aspects of flight, thereby enhancing safety and efficiency.

Using the FMS autopilot mode, pilots can input their flight plan, and the system will take over navigation tasks, ensuring that the aircraft follows the planned route accurately. This not only reduces the workload on pilots, especially during long flights, but also helps maintain situational awareness by allowing them to concentrate on monitoring systems, communication with air traffic control, and managing other operational tasks.

The other options do not accurately capture the primary function of the FMS autopilot mode. While it does contribute to aircraft performance and system management, its core purpose is more focused on navigation assistance and workload reduction rather than automatic control of all systems, performance enhancement, or emergency maneuvers.