Brief History of Project Blue Book

This document provides a brief history of the United States Air Force's investigation into unidentified aerial phenomena, commonly referred to as 'flying saucers.' The Air Force officially began tracking these reports in the fall of 1947, following concerns regarding national air defense. By December 1947, the Air Materiel Command at Wright-Patterson Air Force Base was tasked with collecting and evaluating sighting data. A formal announcement regarding the project's findings was made on December 27, 1949, after 375 reports had been investigated. At that time, the majority of sightings were attributed to misinterpretations of conventional objects, meteorological phenomena, light aberrations, or hoaxes. The document notes that the Air Force has since investigated approximately 5,000 reports, with roughly 10 percent remaining unexplained. The primary difficulty in evaluating these cases is the lack of precise data, such as size, shape, composition, and flight characteristics. While some instruments have been used to gather data, such reports remain infrequent. The Air Force maintains that no pattern has emerged to suggest these phenomena pose a menace to the United States. Regarding radar sightings, the document explains that many unusual images on radar scopes are caused by temperature inversions, where ground objects are reflected by layers of warm air, or by ionized clouds. A specific incident in January 1951 near Oakridge, Tennessee, is cited as an example of a temperature inversion reflection, where Air Force aircraft attempted to intercept an object that appeared on radar but could not be identified. The document concludes by reaffirming that these phenomena are not secret United States weapons or aircraft, nor is there evidence linking them to other planets.