What feature is commonly associated with the segmented circle airport marker system at night?

The segmented circle airport marker system is designed to provide pilots with crucial information about airport operations and conditions, especially as they approach and navigate around the airport. At night, visibility is reduced, and the illuminated aspect of this system becomes essential for ensuring safety.

The correct feature associated with the segmented circle at night is illumination by lights. This illumination helps enhance visibility and allows pilots to easily recognize the airport's configuration and available runways or other important areas. Proper lighting is pivotal for nighttime operations, as it aids in reducing the risk of accidents and enhancing situational awareness for pilots.

While flags, bright colors, and reflective surfaces can aid visibility in daylight, they do not offer the same level of clarity and safety during nighttime operations. The illumination by lights ensures that pilots can accurately identify the segmented circle’s purpose and navigate accordingly. This factor significantly contributes to effective communication between the airport and the aircraft operating within its vicinity during night hours.