Plain English Meaning

A line of lights set into the runway surface that shows the pilot exactly where the middle of the runway is, especially useful when visibility is poor. The colors change near the end of the runway to warn the pilot that the runway is running out.

Full Definition

A system of flush-mounted lights installed along the centerline of a runway, spaced at regular intervals, to provide visual guidance during landing rollout and takeoff 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.

Context Anchor

Seen on instrument approach charts, airport lighting descriptions, and in tables that tell pilots what changes when certain are not working.