Unidentified Aerial Objects — Project Sign Technical Report

This technical report, dated February 1949, provides a comprehensive overview of the findings of Project Sign, an initiative by the Air Materiel Command to investigate and evaluate reports of unidentified aerial objects. The report notes that approximately 243 domestic incidents had been reviewed at the time of writing. The primary objective of the project was to determine whether these sightings posed a threat to national security. The authors state that no definitive evidence exists to prove or disprove the existence of these objects as unconventional aircraft. The report categorizes the sightings into four main types: flying disks, torpedo or cigar-shaped bodies, spherical or balloon-shaped objects, and balls of light. The analysis suggests that many of these reports can be explained as misidentifications of conventional objects, such as weather balloons, or as the result of psychological factors like 'vertigo' or optical illusions. The report includes detailed discussions on the aerodynamic and propulsion requirements for such objects, noting that if they were real aircraft, they would require advanced technology far beyond current capabilities. The authors explicitly address the hypothesis of extraterrestrial origin, concluding that it is extremely improbable and that the evidence is insufficient to support such a claim. The report also considers the possibility of foreign, specifically Soviet, development of such technology, but finds this unlikely due to the lack of evidence of such advanced research. The document includes several appendices, including a distribution list, graphical data on sightings, and a study by Dr. James Lipp of the Rand Project regarding the feasibility of space travel. The report concludes that while the project has not yet reached a definitive answer, the establishment of procedures for reporting and training personnel is a valuable activity for military intelligence. It recommends that the project be continued, with a focus on gathering more factual evidence, such as radar data and photographs, to better evaluate future reports. The report maintains an unclassified status, though it contains references to secret correspondence and internal military communications regarding the handling of these reports.