Approach Lighting System - Configurations

Configurations

Several ALS configurations are recognized by the International Civil Aviation Organization (ICAO); however, non-standard ALS configurations are installed at some airports. Typically, approach lighting systems are of high-intensity. Many approach lighting systems are also complemented by various on-runway light systems, such as Runway End Identifier Lights (REIL), Touchdown Zone Lights (TDZL), and High Intensity Runway Lights (HIRL). The most common approach light system configurations include:

• MALSR: Medium-intensity Approach Lighting System with Runway Alignment Indicator Lights
• MALSF: Medium-intensity Approach Lighting System with Sequenced Flashing lights
• SALS: Simple Approach Lighting System
• SSALS: Simplified Short Approach Lighting System
• SSALR: Simplified Short Approach Lighting System with Runway Alignment Indicator Lights
• SSALF: Simplified Short Approach Lighting System with Sequenced Flashing Lights
• ODALS: Omnidirectional Approach Lighting System
• ALSF-1: Approach Lighting System with Sequenced Flashing Lights configuration 1
• ALSF-2: Approach Lighting System with Sequenced Flashing Lights configuration 2
• CALVERT I/ICAO-1 HIALS: ICAO-compliant configuration 1 High Intensity Approach Lighting System
• CALVERT II/ICAO-2 HIALS: ICAO-compliant configuration 2 High Intensity Approach Lighting System
• LDIN: Lead-in lighting
• REIL: Runway End Identification Lights
• RAIL: Runway Alignment Indicator Lights

In configurations that include sequenced flashing lights, the lights are typically strobes mounted in front of the runway on its extended centerline. These lights flash in sequence, usually at a speed of two consecutive sequences per second, beginning with the light most distant from the runway and ending at the Decision Bar. RAIL are similar to sequenced flashing lights except that they end where the white approach light bars begin. Sequenced flashing lights and RAIL do not extend past the Decision Bar to avoid distracting the pilot during the critical phase of transitioning from instrument to visual flight. Sequenced flashing lights are sometimes referred to colloquially as the rabbit or the running rabbit.