Approach Light System

An airport lighting facility which provides visual guidance to landing aircraft by radiating light beams in a directional pattern by which the pilot aligns the aircraft with the extended centerline of the runway on his final approach for landing. Condenser-Discharge Sequential Flashing Lights/Sequenced Flashing Lights may be installed in conjunction with the Approach Lighting System (ALS) at some airports. Types of Approach Light Systems are: 1) (ALSF-1) Approach Light System with Sequenced Flashing Lights in Instrument Landing System (ILS) Cat-I configuration. 2) (ALSF-2) Approach Light System with Sequenced Flashing Lights in ILS Cat-II configuration. The ALSF-2 may operate as a Simplified Short Approach Light System with Runway Alignment Indicator Lights (SSALR) when weather conditions permit. 3) Simplified Short Approach Light System with Sequenced Flashing Lights (SSALF). 4) Simplified Short Approach Light System with Runway Alignment Indicator Lights (SSALR). 5) (MALSF) Medium Intensity Approach Light System with Sequenced Flashing Lights. 6) Medium Intensity Approach Light System with Runway Alignment Indicator Lights (MALSR). 7) Lead-in-light system (LDIN): Consists of one or more series of flashing lights installed at or near ground level that provides positive visual guidance along an approach path, either curving or straight, where special problems exist with hazardous terrain, obstructions, or noise abatement procedures. 8) Runway Alignment Indicator Lights (RAIL) (Sequenced Flashing Lights which are installed only in combination with other light systems). 9) Omnidirectional Approach Lighting System consists of seven omnidirectional flashing lights located in the approach area of a nonprecision runway (ODALS). Five lights are located on the runway centerline extended with the first light located 300 feet from the threshold and extending at equal intervals up to 1,500 feet from the threshold. The other two lights are located, one on each side of the runway threshold, at a lateral distance of 40 feet from the runway edge, or 75 feet from the runway edge when installed on a runway equipped with a Visual Approach Slope Indicator (VASI). (FAA4)