We’re so used these days to radar tracking systems and GPS information to guide planes from city to city that it’s easy to forget that all those navigation systems were developed well after the first attempts to guide planes in flight.
In the 1920s in the U.S. the development of airmail created the need for a navigation system; passenger and freight traffic was still a few years away. Without a guide, airmail flew in the daytime, then switched to a train for the night to be picked up and continued by a plane the next day.
The early system, built by the federal government, placed 51-foot beacons 10 miles apart across the country. Each had a 2-million candlepower light, a shed for fuel and power with the station’s ID painted on top, and red and green lights giving the station’s identifier. Emergency landing strips were created every 25 miles.
The most unusual piece of the program, however, was an arrow, made of concrete, 50 to 70 feet long and painted bright yellow to guide the pilot to the next station on the route. 1,500 were built, but only about 200 survive. The system as a whole was outdated by 1939, and during WWII, the beacons and sheds were stripped of their metal for the war effort
