An approach lighting system (ALS) is an array of lights that provide visual information on runway alignment, height perception, roll guidance, and horizon references for pilots when making an approach to a runway. It is designed to smooth the transition from instrument to visual flight for landing through a configuration of signal lights that start at the landing threshold and extend into the approach zone.
Depending on the type of precision approach and visibility minimums of the approach, the ALS can be in the form of medium intensity approach lighting system without sequenced flashers (MALS), medium intensity approach lighting system with sequenced flashing lights (MALSF), medium intensity approach lighting system with runway alignment indicator lights (MALSR), simplified short approach lighting system with runway alignment indicator lights (SSALR), approach lighting system with sequenced flashers II (ALSF-2), omni-directional approach lighting system (ODALS), or precision approach path indicator (PAPI) system.
at the Open Lighting Product Directory (OLPD)
