Project Grudge Technical Report — August 1949

This technical report, issued by the Air Materiel Command in August 1949, provides a comprehensive analysis of unidentified aerial objects investigated under Project Grudge. The document outlines the history of the project, which succeeded Project Sign, and details the methodology used to evaluate reports received between 1947 and 1949. The authors note that the sudden surge in reports was largely triggered by the widely publicized account of Kenneth Arnold in June 1947, which introduced the term 'flying saucers' to the public lexicon. The investigation involved collaboration with various consultants, including astronomer Dr. J. A. Hynek, the Rand Corporation, and the Air Weather Service. The report concludes that the vast majority of sightings can be explained as misidentified conventional aircraft, weather balloons, astronomical phenomena, or psychological misinterpretations by observers. The authors argue that there is no evidence to suggest that these objects pose a threat to national security or represent extraterrestrial technology. The report also highlights the unreliability of witness testimony, noting that observers often provide inconsistent or inaccurate estimates of speed, size, and distance. It recommends that future investigations focus on more precise data collection, such as using polar coordinates for sightings and improving the training of observers to distinguish between known phenomena and truly anomalous events. The document includes several appendices detailing the specific findings of the consultants and providing a breakdown of the incidents analyzed.