Douglas DC-4 / C-54 Skymaster

The Douglas DC-4 is a four-engine propeller-driven airliner, heavily utilized by the U.S. military during and after World War II under the designation C-54 Skymaster. These aircraft formed the backbone of long-distance military and civilian air transport in the mid-20th century. Pilots flying these aircraft at cruising altitudes frequently had clear, prolonged views of the sky, leading to numerous high-quality UAP sighting reports.

Commercial and military transport pilots flying DC-4s/C-54s submitted numerous credible UFO sighting reports during the early Cold War era.