July 6, 1920: Pilots Navigate Using AM Radio

(Wired) 1920: A U.S. Navy seaplane departs Hampton Roads, Virginia, and heads out over the ocean. Using a new radio compass, the pilots are able to locate and fly directly to a Navy ship nearly 100 miles offshore. It’s the first use of radio navigation by an aircraft.
During the post–World War I boom in aviation, pilots navigated primarily the same way drivers did at the time: They followed roads. Using maps, pilots could follow roads — or perhaps rivers or other prominent features — from place to place.
Unfortunately, unless a pilot knew the way, there was no way to directly navigate between two locations. For the Navy, the problem was a bit more difficult. Continued

Image: Wikipedia