What is the primary function of the flight management system (FMS) in modern aircraft?

The primary function of the flight management system (FMS) in modern aircraft is to automate navigation, performance optimization, and flight planning tasks. The FMS integrates various data from the aircraft's navigation systems along with performance data and flight plans entered by pilots or retrieved from external sources. It helps streamline operations by allowing the pilots to focus on managing other critical aspects of flight.

The FMS calculates the most efficient route and can adjust the flight path in real-time based on various factors such as weather conditions, air traffic, and changes in the flight plan. This level of automation not only enhances safety by reducing pilot workload but also optimizes fuel use and improves overall flight efficiency.

While controlling aircraft speed and altitude is important, these functions are part of a broader set of tasks that the FMS manages rather than its primary role. Monitoring fuel consumption and weight distribution, while important for flight safety and efficiency, is a function more related to performance management systems than the FMS itself. Providing real-time weather updates is usually handled by other onboard systems or external data services, which then may be integrated into the FMS for information but do not define its core purpose.