Rotating Beacon

A light mounted on top of a tower or building at an airport that flashes to help pilots locate the airport visually, especially at night or in low visibility. Civilian land airports use alternating white and green flashes, while military airports use alternating white and green with dual white flashes. During daylight hours, an operating beacon at a towered airport indicates that the weather is below basic VFR minimums (ceiling below 1,000 feet or visibility below 3 miles).