Definition
A row of flush-mounted lights installed along the centerline of a runway, spaced at regular intervals, used to provide pilots with centerline guidance during takeoff and landing in low-visibility conditions. The lights are white for most of the runway, transition to alternating red and white as the runway end approaches, and become solid red for the final portion before the end of the runway.
Plain English
A line of lights set into the runway surface along its center, helping the pilot see and follow the middle of the runway when visibility is poor. The colors change near the end of the runway to warn the pilot that the runway is running out.
Context Anchor
Seen in approach charts, airport lighting descriptions, and inoperative lighting notes for instrument approaches.
Why Pilots Care
These lights allow pilots to maintain precise runway alignment when visibility is reduced, supporting safe takeoffs and landings.
Grounding Statement
In poor visibility, RCLS give the pilot a lit path down the middle of the runway.
Intuition Check
RCLS are not runway edge lights. They mark the center of the runway surface, not the sides.
Example Sentence 1
With visibility down to half a mile, the runway centerline lights gave us clear guidance during the landing rollout.
Example Sentence 2
When the RCLS were inoperative, the approach required a higher minimum visibility.