Early navigation aids including beacons

The worker connecting this beacon shows its size. These were installed in the 1920s. Beacons were usually electric, though gas was used in remote areas. Since beacons had to be placed on tall peaks and obstacles, engineering and construction was often difficult. For some common routes beacons were set 10 miles apart so pilots could always see one in clearer weather. In the 1930s away from common routes navigation was often follow the rails and read the names of towns on the water tanks.

In the 1940s radio navigation enabled accurate travel at night and when weather limited visibility, but also during CAVU (ceiling and visibility unlimited) conditions pilots had a network of radio beacons to lead them to cities over the horizon.