THE DALLES OREGON, [ILLEGIBLE] 1952Circa 1952

On July 25, 1952, multiple observers at the 674th Air Control and Warning Squadron in Osceola, Wisconsin, reported unusual radar contacts and visual sightings. The incident was significant because it involved both electronic and eyewitness accounts by trained military personnel operating at a radar station.

Early in the morning of July 25, radar operators began tracking unidentified objects on their scopes. The targets appeared as blips that varied in size and behavior. Some targets appeared as complete arcs that would fade as a unit rather than disappearing piece by piece. The radar showed no organized formation, and speeds varied greatly, ranging between 14,100 and 720,000 knots as computed on the 200 nautical mile range setting. The targets seemed to follow a general clockwise pattern, moving southeast, then westerly, and finally north easterly. One complete cycle took approximately two minutes and forty-five seconds, with about one minute between cycles. This pattern repeated throughout the sighting period.

Meanwhile, ground observers at the station visually watched short yellowish flashes moving rapidly across the sky. Each flash lasted about one second, with three to six seconds between flashes. The lights progressed from east to west, south of the station, at what observers judged to be about twenty degrees above the horizon. There was some correlation between what the radar operators detected and what the visual observers saw, suggesting both types of sighting may have been of the same phenomena occurring in the same location at the same time.

Two F-51 fighter aircraft were scrambled from the 109th Fighter Squadron to intercept or identify the unknown targets. The aircraft arrived in the area and attempted radar contact. One aircraft achieved lock-on with a target that appeared larger than an F-51 at 14,000 yards, with the target moving at forty knots faster than the interceptor. When the aircraft increased speed to 350 knots and climbed to 18,500 feet, the target appeared to level off and increase speed further. The chase was broken off because no visual contact was achieved.

Air Force analysis of the radar photographs suggested interference from another radar set operating at a similar frequency and antenna rotation speed. The radar station at Elkhorn, Wisconsin, was identified as a possible source of such interference. The periodic appearance of targets on the radar scope may have been caused by the slight difference in antenna rotation speeds between the two radars, with interference occurring when the antennas pointed toward each other. The file notes that weather data would have been useful in determining whether a distant radar set could have caused the interference.

The full case file is reproduced below as held by the National Archives (51 pages).