Definition
A configuration of high-intensity lights arranged in a specific pattern extending outward from the runway threshold along the extended runway centerline, designed to provide visual guidance for aircraft transitioning from instrument flight to visual reference for landing. Approach light systems vary in length and configuration depending on the runway and approach category, and may include features such as sequenced flashing lights and decision bars to help the pilot identify the runway environment, align with the centerline, and judge height above the ground.
Plain English
A line of bright lights on the ground stretching out from the start of the runway, pointing back toward where an arriving aircraft will appear. The pattern helps the pilot see the runway and line up with it when breaking out of cloud or low visibility.
Context Anchor
You will see this term in airport lighting descriptions, instrument approach information, and discussions of landing in low visibility or at night.
Derivation
“Approach” originally means coming nearer. In aviation, it specifically means the part of flight leading toward landing, so an Approach Light System is lighting built for that final path to the runway.
Why Pilots Care
Allows safe landing in reduced visibility by providing visual reference to the runway alignment and threshold location.
Grounding Statement
Picture a line of lights extending outward from the runway end, showing the pilot where the runway centerline continues into the approach path.
Intuition Check
Do not read this as just “lights near the runway.” An Approach Light System is a specific runway lighting aid placed before the landing end to guide aircraft toward the runway.
Example Sentence 1
Breaking out at minimums, the pilot saw the approach light system and continued the descent toward the runway.
Example Sentence 2
Runways with an Approach Light System often permit lower landing minimums because the lights give pilots a reliable visual reference.