What is the indication of runway edge lights?

Runway edge lights serve the critical function of marking the lateral boundaries of the runway during periods of low visibility or at night. The correct answer indicates that these lights are white until they change to amber for the last 2,000 feet of the runway. This transition to amber serves as a cautionary signal to pilots, indicating they are approaching the end of the usable runway surface.

The use of white lights along the main length of the runway provides clear visual guidance during takeoff and landing phases. The amber lights within the final 2,000 feet help to prevent runway overruns, alerting pilots to the fact that they are nearing the end of the runway where more caution is needed. This design helps to enhance safety by providing visual cues that accommodate different stages of approach and landing.

The other choices do not accurately represent the standard use or arrangement of runway edge lights. Flashing white lights are not used as edge lights, all red lights typically indicate a runway that is closed or unsafe, and green lights marking the start of the runway are more applicable to threshold lights rather than edge lights. Understanding the specific visual cues provided by runway lights is essential for ensuring safe operations during flights, especially in challenging visibility conditions.