AIM Text
- An aeronautical light beacon is a visual NAVAID displaying flashes of white and/or colored light to indicate the location of an airport, a heliport, a landmark, a certain point of a Federal airway in mountainous terrain, or an obstruction. The light used may be a rotating beacon or one or more flashing lights. The flashing lights may be supplemented by steady burning lights of lesser intensity.
- The color or color combination displayed by a particular beacon and/or its auxiliary lights tell whether the beacon is indicating a landing place, landmark, point of the Federal airways, or an obstruction. Coded flashes of the auxiliary lights, if employed, further identify the beacon site.
Source: FAA Aeronautical Information Manual · current edition · paragraph 2-2-1.
Research Notes
AIM 2-2-1 covers Airport Beacon — the rotating beacon that identifies airport type and operational status.
Beacon meanings:
- White + green: Civilian land airport
- White + white + green: Civilian water (seaplane base)
- White + green + military stars: Military airport
- Yellow + yellow + green: Heliport
Daytime operation: If the beacon is operating during daylight at a Class B/C/D airport, it means the field is currently below VFR minimums (1,000 ceiling or 3 SM visibility). This is one of the few exceptions where the beacon is intentionally lit during the day.
Reference: AIM 2-2-1.