How are Runway CenterLine Lights (RCLS) spaced?

Runway CenterLine Lights (RCLS) are installed to enhance visibility and guide pilots along the centerline of the runway during takeoff and landing, particularly in low visibility conditions. The correct spacing for these lights is every 50 feet, beginning 75 feet from the threshold of the runway.

This setup allows RCLS to provide a consistent and clear visual reference for pilots, ensuring that they have ample guidance as they approach and traverse the runway. The 75-foot distance before the threshold marks the point where the lights start, which is strategically chosen to give pilots a clear visual cue just before the landing or takeoff point, while the 50-foot spacing maintains consistent illumination along the runway's centerline.

Other spacing options, such as 100 feet, 25 feet, or irregular patterns, would not provide the optimal visual reference needed for safe operations. The specific choice of 50-foot intervals has been established based on safety data and operational needs to maximize visibility and control during critical phases of flight.