The ALSF-1, ALSF-2 and ALSF-2/SSALR are approach lighting systems with sequenced flashing lights that are used at airports and military air bases to provide landing approach guidance, such as runway alignment, height perception, horizontal reference and roll guidance extending from the landing threshold outward (2,400-3,000 feet) into the approach zone.
- FAA: Designed according to ALSF-1, ALSF-2, ALSF-2/SSALR FAA-E-2628; FAA-E-2325 (Sequenced Flashing Components)
- ICAO: Annex 14 para. 220.127.116.11, 18.104.22.168, 22.214.171.124, 126.96.36.199, and 188.8.131.52
- U.S. Military: AFMAN(I) 32-1187/TM 811-5 (UFC 3-535-01) Approach Applications