Wakkana, Japan, November 1948 - Incident Number: 198November 1948

On November 6, 1948, a radar operator at a U.S. Air Force base near Wakkanai, Japan detected an unidentified aircraft circling directly above the radar station. The object appeared on radar as a single blip at first, then changed behavior in ways that caught the operator's attention. The radar contact lasted one hour and five minutes, during which the aircraft moved erratically, changing direction continuously.

The radar showed the object's speed varying between 100 and 240 miles per hour. At times, the blip maneuvered in a way that reminded the operator of two fighter aircraft dog-fighting, with constant course changes. Because there was no visual observation and the radar target was moving at high speed while frequently changing direction, investigators noted that if the radar report was accurate, the object could not have been a balloon.

The Air Force sent questions to the Far Eastern Air Force asking for details: the target's altitude, azimuth, speed and heading when first detected, whether radar evasion tactics were being used, and whether the aircraft had been heard or seen visually. The weather that day featured low clouds forming a very dense overcast of unknown height. Due to adverse weather, no attempt was made to intercept the object.

The Air Force evaluated the unidentified aircraft as a Soviet aircraft conducting an electronic reconnaissance mission, sometimes called a "Ferret" mission, meaning it was gathering information about American radar capabilities. However, the case file includes an assessment that the object had no astronomical explanation, and the radar blip's behavior remained difficult to fully explain due to permanent radar ground clutter near the station that made tracking challenging.

The full case file, consisting of 16 pages, is reproduced below as held by the National Archives.