When do the runway edge lights change color?

The chosen answer correctly states that runway edge lights change color to yellow in the last 2000 feet or half of the runway. This change serves as a critical visual cue for pilots, indicating that they are approaching the end of the runway. The yellow lights enhance situational awareness, especially during landing, alerting pilots to prepare for the potential end of the usable runway area. This feature is designed to aid in better decision-making regarding landing techniques, particularly in fields of operations where runway lengths might be limited.

In contrast, the other statements do not accurately describe the standard procedures for runway edge light color changes. Yellow lights as a warning are established practice, while other colors, such as red, are typically associated with different lighting systems that might indicate a runway incursion or approach to a non-active area, but they aren't utilized for edge lights in the way described in the options presented. The consistency of white lights along the entire length of the runway prior to the change to yellow further underscores the importance of the defined transition at the indicated distance.