Project Sign

Project Sign was established by the U.S. Air Force on January 22, 1948, as the first official military investigation of unidentified flying object reports. The project was created in response to the wave of UFO sightings that began with Kenneth Arnold's report of mysterious aircraft over Mount Rainier in June 1947 and continued with the Roswell incident and numerous other sightings throughout the summer.

The project was headquartered at Wright-Patterson Air Force Base in Ohio and was tasked with determining whether UFO reports posed a national security threat. Air Force personnel collected and analyzed reports from military and civilian witnesses, conducting investigations and interviews to determine the nature and origin of the observed phenomena.

Project Sign's investigators were divided into two factions regarding the nature of UFO reports. Some personnel, influenced by the quality and consistency of certain reports from credible witnesses, became convinced that some UFOs represented extraterrestrial visitation. This group produced the "Estimate of the Situation," a classified report that concluded some UFOs were likely of extraterrestrial origin.

The extraterrestrial hypothesis was rejected by Air Force Chief of Staff General Hoyt Vandenberg, who ordered the Estimate destroyed and demanded a more skeptical approach to UFO investigations. This led to a reorganization of the project and a shift toward conventional explanations for UFO reports, including misidentified aircraft, weather phenomena, and psychological factors.

Project Sign was officially terminated on February 11, 1949, and replaced by Project Grudge, which adopted a more dismissive stance toward UFO reports. Despite its brief existence, Project Sign established the template for subsequent government UFO investigations and demonstrated the tension between open scientific inquiry and institutional skepticism that would characterize official UFO studies for decades.