Project Sign Final Report
The final report of the United States Air Force's first official study of unidentified flying objects, conducted at Wright-Patterson Field from 1947 to 1948.
Project Sign was the United States Air Force's first formal investigation of unidentified flying objects, established at the Air Materiel Command at Wright-Patterson Field after the wave of reports that followed Kenneth Arnold's June 1947 sighting. Its analysts examined cases including the death of pilot Thomas Mantell and the Chiles-Whitted airliner encounter.
This final technical report, issued in February 1949 as F-TR-2274-IA, set out the project's findings and recommendations. Sign was succeeded by Project Grudge later in 1949, and then by Project Blue Book in 1952. The full declassified text is below.
Source: US Air Force, Project Blue Book archive, declassified. Public domain (US Government work).
