Puget Sound area, WashingtonJune 1958

On June 9, 1958, a first lieutenant in the U.S. Air Force was flying an F-102 interceptor at around 40,000 feet near Puget Sound, Washington, when he spotted an unusual object in the sky. The pilot described it as roughly cylindrical, with a white or pinkish-white color and a darker center, traveling at high speed toward the north while his aircraft was heading south.

The pilot banked left to keep the object in sight. As he watched, the object appeared to climb, slow down, and execute a large 360-degree turn. It then descended and began moving toward the aircraft, making four or five smaller orbits around the F-102 as the pilot climbed to 52,000 feet. During these close passes, the dark center of the object became clearly visible to the pilot. The object finally pitched up at a 45-degree angle, accelerated rapidly, and disappeared to the northwest within three to four seconds. The entire sighting lasted about four minutes.

Air Force investigators found several clues pointing to a weather balloon. A balloon had been released by the U.S. Weather Service about 20 minutes before the sighting from the same area. Wind data showed patterns consistent with the object's observed movements at different altitudes: winds from the southeast to northwest at 40,000 feet, and from west to northeast at higher altitudes. The balloon's documented path took it to at least 90,000 feet, matching the estimated altitude and direction of travel. The pilot's detailed size estimates (3/4 inch diameter, 1/16 to 1/32 inch depth) also raised questions about precision measurements made while flying at 600 miles per hour.

However, investigators noted a known phenomenon: pilots maneuvering to keep small distant objects centered in their view sometimes perceive the object as moving around them, when actually the aircraft is circling a stationary or slow-moving object. At high altitudes with no visible landmarks for reference, this illusion becomes particularly easy to experience. Investigators also observed that the object's behaviors, such as oscillation and apparent changes in speed and altitude, align with typical balloon characteristics. The pilot reported he did not check his radar scope during the sighting, and neither nearby pilots nor radar operators reported seeing anything unusual.

The Air Force concluded the object was probably a balloon, noting that the wind patterns, balloon release timing, and documented altitude all supported this conclusion. The full case file is reproduced below as held by the National Archives, comprising 17 pages.