What visual characteristic is associated with Runway Alignment Identifier Lights (RAILs)?

Runway Alignment Identifier Lights (RAILs) are designed to provide visual guidance to pilots during approach to the runway, particularly in low-visibility conditions. The characteristic of RAILs being solid white is crucial as it helps in distinguishing them from other airport lighting systems that utilize different colors or flashing patterns.

The solid white lights serve to align the aircraft with the runway centerline, ensuring that pilots can maintain the correct approach path. This feature is particularly important for enhancing situational awareness when landing. RAILs are typically placed alongside the runway and are a significant aid for visual approaches.

In contrast, other lighting systems such as approach lights or runway edge lights may incorporate flashing or colored lights to indicate various operational statuses or conditions, but the solid white characteristic of RAILs provides a clear and unambiguous visual indicator for runway alignment.