What is "airway beacon"

An airway beacon was a rotating light assembly mounted atop a tower. These were once used extensively in the United States for visual navigation by airplane pilots along a specified airway corridor. Approximately 1,500 airway beacons were constructed to guide pilots from city to city, covering . Most of the beacons are gone, but The State of Montana continues to maintain several as navigation aids in mountainous terrain. One beacon is preserved for historical purposes in Saint Paul, Minnesota at the Indian Mounds Park on a bluff overlooking the Mississippi River. Recently, the beacon at Grants, New Mexico was restored for historic preservation, using original items found at other nearby sites.

A large concrete slab, in the shape of an arrow, was located near the base of each beacon. Many of these arrows remain today, some of which are visible from satellite pictures, even in urban settings.