Runway centerline lights provide what arrangement?

• A. They outline the runway edges
• B. They are located at the threshold only
• C. They are flush centerline lights spaced at 50-foot intervals beginning 75 feet from the threshold
• D. They are used for REIL identification

Answer: (C)

Runway centerline lights form a flush row along the runway centerline, spaced 50 feet apart, beginning 75 feet from the threshold and extending down the runway. This arrangement provides a continuous visual cue to keep the aircraft aligned with the centerline during approach, landing, and rollout, which is especially helpful in low visibility or at night. They are not used to outline runway edges (that’s edge lighting) and they're not the threshold identification lights (REIL).