Sighting of Unidentified Object — Minneapolis, Minnesota, October 15, 1953

On October 15, 1953, between 1010 and 1015 CST, three research engineers from General Mills were conducting theodolite tracking of a 79-foot balloon (Project Grab Bag) at an altitude of approximately 80,000 feet. While observing from the roof of 2003 East Hennepin Avenue in Minneapolis, Minnesota, they witnessed an unidentified object passing below the sun. The object was first detected by a white smoke or vapor trail extending behind it. Although the object itself was not initially visible through the theodolite, it was later seen as a grey mass. The object traveled in horizontal flight at an estimated altitude of 40,000 feet, covering 10 degrees of the sky in 9 seconds, which the observers calculated to be approximately 900 miles per hour. After about 10 seconds of horizontal flight, the object entered a vertical dive lasting 10 to 15 seconds. During this maneuver, the object was visible two or three times as it appeared to glow or reflect sunlight. The vapor trail ceased at the end of the dive, and the object was seen leveling off. The observers noted that the object's speed was higher than normally observed and that the vertical dive was a highly dangerous, if not suicidal, maneuver. Furthermore, they noted that a jet aircraft in such a dive would typically produce a shock wave and be audible, neither of which occurred. The observers, who possessed extensive engineering backgrounds, believed the object was likely a jet aircraft, but they found the performance characteristics, particularly the vapor trail behavior and the vertical motion, to be highly unusual. The report was forwarded to the Air Intelligence Service Squadron and subsequently to the Air Technical Intelligence Center. Official follow-up indicated that while two F-86 aircraft were in the area, the information did not definitively correlate with the sighting. The incident remains documented as an unusual observation.