Aerodrome Beacon

An aerodrome beacon is a beacon installed at an airport or aerodrome to indicate its location to aircraft pilots at night. An aerodrome beacon is mounted on top of a towering structure, often a control tower, above other buildings of the airport. It produces flashes not unlike that of a lighthouse. Airport and heliport beacons are designed in such a way to make them most effective from one to ten degrees above the horizon; however, they can be seen well above and below this peak spread. The beacon may be an omnidirectional flashing xenon strobe, or it may rotate at a constant speed which produces the visual effect of flashes at regular intervals. Flashes may be of just a single color, or of two alternating colors.
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Aeronautical beacon used to indicate the location of an aerodrome from the air. (FAA4)

[ICAO]
Aeronautical beacon used to indicate the location of an aerodrome from the air.