Which two components are major parts of avionics systems?

The selection of flight management systems (FMS) and communication navigation systems (CNS) as major parts of avionics systems is justified by the integral roles these components play in aircraft operations.

The flight management system (FMS) is essential for automating the flight planning and navigation processes of an aircraft. It allows for the input of a route plan, which the FMS can follow automatically, managing the flight path, providing guidance, and calculating the most efficient route, thereby enhancing operational efficiency and safety.

Communication navigation systems (CNS) encompass a broader category of technologies that include various systems for communication with air traffic control and navigation aids that assist in determining the aircraft's position. This includes vital equipment such as radios, GPS, and other navigation aids necessary for safe and efficient flying.

Both FMS and CNS are foundational elements that integrate different aspects of flight operation, from managing in-flight navigation to ensuring effective communication between the aircraft and ground control, making them core components of modern avionics systems.

In contrast, while weather radar systems, autopilots, altitude indicators, and transponders are important in their own right, they do not encompass the same breadth or centrality to the avionics system as FMS and CNS do.