Photograph of interior of Trans World Airline (TWA) Skymaster

September 26, 1946

Interior of a Trans World Airlines (TWA) Skymaster aircraft equipped for onboard mail sorting and routing. This experimental “Flying Post Office” was tested in the United States by United and American Airlines as well. Adapting the concept used successfully by Railway Post Office (RPO) cars, combining transportation and mail sorting to move mail more quickly. Unfortunately, it was harder for clerks to stand and move in the airplane than on moving trains, and the amount of mail that could be sorted during an airplane flight was too small to make the system practical in the long run, especially as air speeds increased. The Flying Post Offices never moved beyond the experiment stage.