Documents / Report
This August 1949 technical report from the US Air Force Air Materiel Command presents Project Grudge's investigation of unidentified flying objects through January 1949. Drawing on consultants including Dr. J. A. Hynek, Rand Corporation, the Air Weather Service and Dr. P. M. Fitts, it explains most of 244 incidents as balloons, aircraft, astronomical phenomena, hoaxes or psychological errors. It concludes the objects pose no direct threat to national security and recommends reducing the investigation in scope.
Class Number of incidents Approximate percentage 1. Astronomical a. High probability b. Fair or low probability Total 42 18 35 14 2. Non-astronomical but suggestive of other explanations a. Balloons or ordinary aircraft b. Locks, flares, or falling bodies c. Miscellaneous (reflections, auroral streamers, birds, etc.) Total 40 20 23 10 13 5 84 35 3. Non-astronomical, with no evident explanation a. Lack of evidence precludes explanation b. Evidence offered suggests no explanation Total 50 15 40 20 70 38 according to these findings, 75, or almost one-third, of the 237 insidents yet remain without an appropriate hypothesis for explanation. It is likely, of course, that with additional evidence a number of those included in class 34 would be easily explained (some of them, probably, astronomically). There are, however, at least 48 insidents in which the evidence, if correct as given, does not fit any simple explanation, and a number of those were reported by presumably well-qualified observers.
Report, from the classic collection. The PDF is mirrored here; the original link is under it. The text was read from the page images by an OCR model; expect the odd misread word. 413 pages are in the text index: search them above, or from the library's search.