So what if there were no high-tech GPS devices in the 1920s? Back then the US Postal Service invented its own navigation system – giant concrete arrows that pointed the way to Air Mail pilots.
When America’s first Transcontinental Air Mail route opened in 1920, pilots faced difficulties in navigating the coast-to-coast route over the American Midwest. This was a time when radar and other modern flight planning implements were yet to be invented.
The very first pilots had to traverse the route relying on landmarks, which weren’t always visible during bad weather. So in 1923, Congress approved the construction of a network of beacons to make the route navigable in the rain or the dark.
These beacons consisted of massive concrete arrows, painted bright yellow, set into the land about 10 miles apart. The arrows were illuminated by 50-foot-towers with powerful rotating gas lights. Visible from a height of 10,000 meters, the arrows helped pilots find their way during the worst weather and at night. They were also located close to emergency airfields just in case airplanes needed to make an emergency landing.
