Plain English Meaning
A line of bright strobe lights leading up to the runway that flash one after another, fast, so it looks like a ball of light is racing toward the runway. The motion points the pilot to where the runway begins.
Full Definition
High-intensity white strobe lights installed along the approach lighting system that flash in rapid sequence from the outermost light toward the runway threshold, creating a visible 'ball of light' that travels toward the runway approximately twice per second. They guide pilots to the runway during instrument approaches in low-visibility conditions.
Context Anchor
Seen in approach lighting system descriptions and during instrument approaches to runways equipped with these lights, especially at night or in reduced visibility.