page_title: Transcontinental Airway System
section_title: Technical
hierarchical_section_title: Transcontinental Airway System / Technical
caption_attribution_description: English: Beacon 61B from the en:Transcontinental Airway System route "CAM-8", originally installed near Castle Rock, Washington.
context_page_description: The Transcontinental Airway System was a navigational aid deployed in the United States during the 1920s.
context_section_description: The lighted Airway Beacons were a substantial navigation aid in an era prior to the development of radio navigation. Their effectiveness was limited by visibility and weather conditions.
  24 inches (610 mm) diameter rotating beacons were mounted on 53-foot (16 m) high towers, and spaced ten miles apart. The spacing was closer in the mountains, and farther apart in the plains. The beacons were five million candlepower, and rotated six times a minute. "Ford beacons" (named after Ford Car headlights) were also used, placing four separate lights at different angles.
  Airports used green beacons and airways used red beacons. The beacons flashed identification numbers in Morse code. The sequence was "WUVHRKDBGM", which prompted the mnemonic "When Undertaking Very Hard Routes Keep Directions By Good Methods". Engineers believed the variations of beacon height along hills and valleys would allow pilots to see beacons both above ground fog, and below cloud layers.
  Towers were built of numbered angle iron sections with concrete footings. Some facilities used concrete arrows pointing in the direction of towers. In areas where no connection to a power grid was available, a generator was housed in a small building. Some buildings also served as weather stations. Many arrow markings were removed during World War II, to prevent aiding enemy bombers in navigation, while 19 updated beacons still remain in service in Montana.
caption: Beacon 61B on a modern display tower, originally installed on route CAM-8 near Castle Rock, WA
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