What alert does a runway edge light system change from white to yellow indicate?

The transition of a runway edge light system from white to yellow serves as a critical visual cue for pilots, indicating that they are approaching a caution zone during landing operations. This change in color alerts pilots that they are nearing the end of the usable runway and that they should prepare for potential obstacles or the need to execute a go-around.

In operations, yellow lighting typically signifies an area where special care is required, such as proximity to the runway's end or areas where the surface might not be suitable for landing. This alert helps to mitigate the risks of runway overshoots and enhances situational awareness, making it an essential aspect of safe landing procedures.

While other scenarios involve different aspects of the runway and taxiway system—such as indicating a clear path or the beginning of taxiways—the specific function of the color change to yellow is tightly aligned with caution while landing, making it a crucial measure for maintaining safety.