Approach lighting system (ALS)

Approach Lighting System (ALS): A system that uses lights to guide pilots safely from instrument to visual flight by providing directional, distance, and glidepath information. The lights are designed to penetrate the atmosphere far enough from the runway touchdown point, giving pilots a clear indication of their position, speed, and altitude. The ALS is an integral part of the airport lighting system and plays a critical role in ensuring the safety of aircraft during the approach and landing phases of flight. Depending on the runway configuration, the ALS may consist of a variety of lighting configurations, including runway threshold lights, end lights, and touchdown zone lights, as well as various combinations of approach lighting arrays and sequencing flashers. These lights provide pilots with a clear visual guide, helping them to perform safe and smooth landings in all weather conditions.