Plain English Meaning

A row of lights leading up to the runway, with extra flashing lights that pulse one after another toward the runway. The flashing pattern points the pilot straight at the touchdown end so they can line up and land in poor visibility.

Full Definition

An approach lighting system installed at the approach end of certain runways, consisting of a shortened configuration of steady-burning white lights extending outward from the runway threshold along the extended runway centerline, combined with sequenced flashing lights that fire in rapid succession toward the threshold to give the pilot a strong directional cue during the final segment of an instrument approach.