---------------------------------------------------------------- ================================================================ PROJECT 10073 RECORD CARD -- TRANSCRIPTION File: 1953-10-6981338-Minneapolis-Minnesota.pdf Transcribed from document image by Claude Sonnet 4.6 ================================================================ FIELD 1 -- DATE: 15 Oct 53 FIELD 2 -- LOCATION: Minneapolis, Minnesota [Supplemental documents specify the observation post as the roof of General Mills Aeronautical Laboratories, 2003 East Hennepin Avenue. The AF Form 112 Air Intelligence Information Report lists area as Ft. Snelling, Minnesota, where the 31st Air Division was headquartered. The balloon being tracked was floating over St. Paul.] FIELD 3 -- DATE-TIME GROUP: Local 1010-1015 CST / GMT 1610Z FIELD 4 -- TYPE OF OBSERVATION: Ground-Visual [X] Ground-Radar [ ] Air-Visual [ ] Air-Intercept Radar [ ] FIELD 5 -- PHOTOS: No [X] FIELD 6 -- SOURCE: Civilians (three research engineers, General Mills Aeronautical Laboratories) FIELD 7 -- LENGTH OF OBS: 40 seconds [Individual estimates vary: 20-25 sec (observer 1), 45-55 sec (observer 2), 40-45 sec (observer 3). The AF Form 112 summary states approximately 30 sec horizontal and 10-15 sec vertical dive, totaling roughly 40-45 seconds.] FIELD 8 -- NUMBER OF OBJECTS: One FIELD 9 -- COURSE: SE (southward; observers describe the object heading southward then entering a near- vertical dive) FIELD 10 -- BRIEF SUMMARY: Three research engineers observed a white smoke or vapor trail at 40-50,000 ft, while tracking a 79 ft balloon at 73,000 ft through a theodolite. Object moved in horizontal flight for approximately 30 seconds at a rate of 10 degrees per 9 seconds (estimated 900 mph at 40,000 ft). Object then began a vertical dive lasting 10-15 seconds during which it was visible several times appearing to glow. As object leveled off from dive, smoke trails ceased. Object last seen as a grey mass through theodolite leveling out, then disappeared in a quick flash like mirror reflecting sunlight. Observation made from roof of General Mills Laboratory. FIELD 11 -- COMMENTS: One of the observers is a meteorological engineer and considered completely reliable; the other two are also considered reliable. Nearest AC&W facility was inoperative at time of sighting. Two F-86 aircraft were in area south and west of Minneapolis at approximate time, however this does not in itself satisfy or correlate with subject observation (per 31st Air Division). FIELD 12 -- CONCLUSIONS: Unidentified [X] Form: FTD SEP 63 0-329 (TDE) [later archival form] Original reporting via AF Form 112, Air Intelligence Information Report, prepared by 2d Lt. Timothy J. Delanty, Flt 2-A, 4602D AISS, approved by Major Walter C. Clarke, Director of Intelligence, 31st Air Division. Supplemental documents include: U.S. Air Force Technical Information Sheets (Form A) from all three observers; Form B summary data from all three observers; speed/altitude calculation chart (Chart I); ATIC message to 31st Air Division requesting flight records search; 31st Air Division response; forwarding cover letter from 31st Air Division HQ. ================================================================ SEARCH INDEX TERMS ================================================================ Minneapolis Minnesota St Paul Fort Snelling 1953 October General Mills Aeronautical Laboratories balloon theodolite Project 83021 Grab Bag vapor trail smoke trail comet-like research engineer meteorologist B-17 pilot supersonic speed vertical dive dive no sound silent 900 mph 40000 feet UNIDENTIFIED F-86 31st Air Division 4602D AISS Delanty Clarke aerodynamics post-graduate balloon tracking instrument theodolite angular velocity horizontal flight glint flash grey mass reflective civilian engineer Hennepin Minneapolis Minnesota 1953 fall October fireball trail ================================================================ CASE ANALYSIS -- Claude Sonnet 4.6 ================================================================ THE OFFICIAL CONCLUSION This case was evaluated as UNIDENTIFIED. The Air Intelligence Information Report carries a source reliability rating of A-2, meaning the sources were judged completely reliable and the content probably true. The preparing officer stated flatly that the information obtained was believed to be completely reliable, and the approving officer -- Major Walter C. Clarke, Director of Intelligence, 31st Air Division -- signed off on that assessment. Two F-86 aircraft were found in the general area but were explicitly not correlated with the sighting. WHAT THE EVIDENCE SHOWS At between 1010 and 1015 CST on 15 October 1953, three research engineers employed by General Mills Aeronautical Laboratories were on the roof of their facility at 2003 East Hennepin Avenue, using a precision theodolite to track a 79-foot research balloon floating at approximately 73,000 feet. While doing so, they observed an unidentified object appear in the same region of sky they were monitoring. The object was first detectable as a comet-like smoke or vapor trail heading southward in horizontal flight, passing below the sun at an elevation of approximately 25 degrees. No sound was detected at any point in the observation. The trail had an unusual characteristic noted by multiple observers: it was constant in length, dissipating at its rear end at the same rate as it was generated at the front -- exactly like the tail of a comet rather than an expanding or persistent contrail. During roughly 30 seconds of horizontal flight, the object moved at approximately 10 degrees of arc in 9 seconds. The observers worked out the speed implications: at their initial altitude estimate of 40,000 feet, this translates to approximately 900 mph. The supplemental chart they prepared shows that across the plausible altitude range of 30,000 to 50,000 feet, the horizontal speed was between 750 and 1,320 mph -- in every scenario, at or above the speed of sound. Even allowing for a generous 20 percent measurement error, the second observer concluded the object was almost certainly moving at supersonic velocity. After the horizontal phase, the object went into what appeared to be a near-vertical dive lasting 10 to 15 seconds. During the dive it was briefly visible several times, appearing to glow or reflect sunlight. As it leveled out, the smoke trail ceased and the object appeared as a grey mass through the theodolite screen. It then disappeared in a quick brilliant flash described by multiple observers as resembling sunlight reflecting off a mirror -- consistent with a rolling or banking maneuver as it recovered from the dive. In the theodolite field, the object appeared to be approximately the same angular size as the 79-foot balloon being tracked. Since the object was at lower altitude and thus closer to the observers, its actual physical size would be smaller than the balloon -- the first observer estimated 40-50 feet in longest dimension. POINTS OF INTEREST / WHAT GIVES ME PAUSE These observers are about as credible as civilian witnesses get. One was a former B-17 pilot working as a meteorological engineer. Another was a private pilot with two years of post-graduate work in supersonic aerodynamics. The third was a development engineer. They were not casual passersby who glimpsed something odd. They were professional aeronautical researchers in the middle of a precision balloon-tracking operation, using a calibrated theodolite with a known reference object (the balloon) in the same field of view. They had the data to do velocity calculations. They did the calculations and reported them. The company matters too. General Mills Aeronautical Laboratories was a major contractor in U.S. high-altitude balloon research programs. These engineers built and tracked balloons for a living. They knew exactly what balloons look like at altitude through a theodolite. The fact that they had a 79-foot balloon at 73,000 feet as a simultaneous reference is significant: they could compare the object's angular size against something they knew precisely. The witnesses identified four specific reasons the object was not a conventional jet aircraft despite initially defaulting to that explanation. The speed exceeded any known jet. The vertical dive maneuver was described as dangerously extreme if not suicidal for a manned aircraft. A jet performing such a dive would have been heard for miles and generated a detectable shock wave -- there was neither. And vapor trails do not ordinarily form during vertical motion (a point confirmed on the spot by Col. Shomo at the 31st Air Division when they reported the sighting that same morning). The F-86 follow-up investigation is the right methodology but yields a clear negative. The 31st Air Division found two F-86s south and west of Minneapolis at approximately the right time. The F-86 Sabre had a maximum speed of roughly 685 mph -- below even the minimum plausible speed calculated for this object. The reported location (south and west of Minneapolis) does not fit the observation direction. No sonic boom was heard. The 31st Air Division concluded explicitly that this does not correlate. The inoperative AC&W radar at the time is noted without commentary in the record. It is what it is: there was no ground radar that might have confirmed or refined the track. BOTTOM LINE This is a well-documented, well-witnessed UNIDENTIFIED with an unusually rigorous evidentiary base. Three trained aeronautical professionals using precision instrumentation observed an object that by their own calculations was moving at supersonic velocity, executed a vertical dive that no manned aircraft of the era could survive, produced no sonic boom despite exceeding the speed of sound, and left a trail that behaved unlike any known vapor or exhaust trail. Their own attempt to explain it as a jet aircraft is documented alongside four specific reasons why that explanation did not hold up. The Air Intelligence officer who prepared the formal report rated the sources completely reliable and the content probably true. The 31st Air Division Director of Intelligence approved that assessment. No satisfactory explanation was found. ================================================================ END OF DOCUMENT ================================================================ ----------------------------------------------------------------