Approach Light System (ALS) : One of several systems designed to guide an aircraft to the runway threshold on final approach during darkness or IFR conditions
Ilan Kelman (ed.), Vulnerability and Resilience Definitions and References, Version 2, 2007. http://www.islandvulnerability.org/docs/vulnres.pd f, (Vulnr and Resilience - Brit) {524}