Runway Centerline Lighting System (RCLS) These lights are installed on some precision approach runways to facilitate landing under low-visibility conditions. They are located along the runway centerline at 50-foot intervals. When viewed from the landing threshold, the runway centerline lights are white until the last 3,000 feet of the runway. The white lights begin to alternate with red for the next 2,000 feet, and for the last 1,000 feet of the runway, all centerline lights are red. Ref. AIM Para. 2-1-5-a