Black Vault compilation, pp. 91-93

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Secretary ot the Air force. Olice of Public Anoirs. Washington. D.C. 20330
Thank you for your request for information on the Air Force's
investigation of unidentified flying objects, or UFO's.
The Air Force investigation of UFO's began in 1948 and was
known as Project Sign. Later the name was changed t~ Project
Grudge, and in 1953, it became Project Blue Book. Between 1948
and 1969 we investigated 12,618 reported sightings. ·
Of these sightings, 11,917 were found to have been caused by
material objects (such as balloons, satellites, and aircraft),
immaterial objects (such as lightning, reflections, and other
natural phenomena>, astronomical objects (such as stars, planets,
the sun, and the moon>, weather conditions, and hoaxes. As
indicated, only 701 reported sightings remain unexplained •
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On December 17, 1969, the Secretary of the Air Force
announced the termination of Project Blue Book. The decision to
discontinue UFO investigations was based on an evaluation of a
report prepared by the University of Colorado entitled,
•scientific Study of Unidentified Flying Objects;• a review of the
University of Colorado's report by the National Academy of
Sciences; past UFO stud i es; and the Air Force's two decades of
experience investigating UFO reports.
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As a result of these investigations, studies, and experience,
the conclusions of Project Blue Book were: (1) no UFO reported,
investigated, and evaluated by the Air Force has ever given any
indication of threat to our national security; (2) there has been
no evidence submitted to or discovered by the Air Force that
sightings categorized as •unidentified• represent technological
developments or principles beyond the range of present day
scientific knowledge; and (3) there has been no evidence
indicating that sighting& categorized as •unidentified• are
extraterrestrial vehicles.
With the termination of Project Blue Book, the Air Force
regulation establishing and controlling the program for
investigating and analyz i ng UFOs was rescinded. All documentation
regarding the former Blue Book investigation was permanently
transferred to the Modern Military Branch, National Archives and
Record Service, 8th and Pennsylvania Avenue, Washington DC 20408,
and is available for public review and analysis.
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