Williams AFB, ArizonaMarch 1953

On March 31, 1953, a civilian test pilot flying near Williams Air Force Base in Arizona spotted what he described as a silver, disc-shaped object traveling at high speed. The sighting lasted about 10 seconds. The pilot was flying roughly 16 miles west of the base when he saw the object moving in a northwesterly direction at an estimated altitude of 5,000 feet. He judged the object to be about 23 feet in diameter.

The object appeared bright against the daytime sky. The pilot said it moved so fast that he and a colleague aboard the aircraft could not determine its exact size or whether it was small and nearby or larger and far away. In his written account, the pilot noted that the object traveled in a straight line, disappearing to the right and away from their position. When asked what he thought he had seen, the pilot suggested it might have been a weather tracking device, though he acknowledged the speed seemed unusually fast for such equipment.

Air Force investigators noted that a weather balloon (called a piball, used to measure wind patterns in the upper atmosphere) had been scheduled for launch at 0400Z (15 minutes before the sighting) from Phoenix, Arizona. However, no balloons aloft in the area were reported to the Air Force's Air Technical Intelligence Center. The Air Force concluded the object was most likely a balloon, though the file does not explain how this conclusion accounts for the reported speed or the absence of balloon reports.

The complete case file, as held by the National Archives, is reproduced below in 11 pages.