MALSR provides visual guidance to landing aircraft. The equipment is installed and operated in the approach area of an active landing runway. This specification is also valid for the Medium Intensity Approach Lighting System with Sequenced Flashing Lights (MALSF) with the exceptions that only three (3) sequenced flasher lights are used instead of five (5) to eight (8) and that these three (3) sequenced flasher lights are located at the 1,000 foot, 1,200 foot, and 1,400 foot steady burning light bars instead of being located beyond the steady burning light field.