NW of Bethel, AlaskaAugust 1947

On a brilliant evening in August 1947, two experienced pilots flying northwest of Bethel, Alaska spotted something unusual in the sky. A pilot and his co-pilot saw a black, disc-shaped object about the size of a C-54 transport plane (a large cargo aircraft used by the military). The object appeared silhouetted against the bright sunset sky as it crossed their flight path at right angles.

Unable to tell at first which direction the object was moving, the pilots climbed to about 1,200 feet to avoid a collision. From this new vantage point, they could see the object was moving away from them at high speed. It was flying at an altitude between 500 and 1,000 feet and maintained a northwest course. The pilots chased the object at 170 miles per hour, but it disappeared from sight in four minutes. Based on the time and distance involved, the pilots estimated the object was traveling at roughly 520 miles per hour, about three times their own speed.

Air Force investigators used the pilots' observations to work backward through the mathematics. They noted that if the object was moving as fast as the pilots claimed, it would have been extremely far away by the time it disappeared from sight, meaning it would have had to be enormous to be visible at that distance. Alternatively, if the object was smaller and closer, its actual speed would have been less than 500 miles per hour. The investigators concluded the pilots had probably spotted a conventional aircraft that was silhouetted against the brilliant evening sky, making it difficult to see details like wings or engines. However, the file notes that astronomical explanations do not fit the details of the sighting. The complete case file is reproduced below as held by the National Archives, consisting of 14 scanned pages.