What is the primary function of a flight director in an aircraft?

The primary function of a flight director in an aircraft is to provide guidance on flying to maintain the desired flight path. The flight director system displays visual cues and commands to the pilot on the primary flight display, indicating how to adjust the aircraft's attitude, altitude, and heading to stay on the desired flight path. This system aids pilots, especially during critical phases of flight such as takeoff, climb, descent, and landing, by helping them interpret the necessary inputs to achieve the intended flight trajectory.

In this context, while managing oxygen levels in the cabin, alerting pilots of potential hazards, or automating the navigation system are important functions within an aircraft, they do not encompass the specific operational role of a flight director. The flight director is fundamentally focused on guiding pilot actions to ensure safe and efficient navigation along the predetermined flight route.