Project Sign Incident Reports and Correspondence (1948-1949)

This document is a comprehensive compilation of reports, correspondence, and investigative findings related to Project Sign, the United States Air Force's early investigation into Unidentified Aerial Phenomena (UAP). The archive spans various incidents occurring in 1948 and 1949 across multiple locations, including the United States, Canada, Germany, and the Philippines. The reports detail sightings by military personnel, pilots, and civilians. Common themes include the observation of 'flying discs,' 'balls of fire,' and other luminous objects. Many of these incidents were subjected to rigorous investigation by the Office of Special Investigations (OSI) and the Air Materiel Command. The document includes detailed incident summary sheets, statements from witnesses, and technical analyses of physical evidence, such as metal fragments found in New Hampshire. A significant portion of the document is dedicated to the investigation of 'green fireballs' observed in the Southwest United States, with input from experts like Dr. Lincoln La Paz. While many sightings were eventually attributed to conventional causes—such as weather balloons, astronomical bodies like Venus, or misidentified aircraft—a subset of reports remained categorized as unexplained. The document also highlights the military's concern regarding the potential for these phenomena to be related to foreign reconnaissance or advanced technology, as evidenced by the evaluation of some sightings as potential Soviet 'Ferret' electronic reconnaissance missions. The archive serves as a record of the systematic, albeit often inconclusive, efforts by the Air Force to categorize and understand these aerial anomalies during the early Cold War period.