Air Materiel Command Report on Unidentified Flying Objects, 1947-1948

This U.S. Air Force Project SIGN file from 1947 and 1948 collects correspondence on unidentified flying objects. In it, Headquarters USAF asks Air Materiel Command for its conclusions, and AMC replies on 8 November 1948 after studying about 180 incidents. AMC concludes that observers saw real flying objects but that there is no proof they are aircraft, and it advises against briefing the press. The file also includes letters to the CIA, a citizen's inquiry, a request for a Rand spaceship study and an intelligence analysis of 1947 sightings.

From the source: Release of 2026-08-07 Incident: 1947-1948, N/A. This file is a collection of U.S. Government memoranda and correspondence relating to “Project Sign,” a 1948 U.S. Air Force program to investigate reports of high-performance airborne objects. The documents characterize some of these reports as being consistent with “real” objects rather than fabrications or resulting from perceptual errors. The U.S. Air Force cites the reported characteristics of the phenomena, e.g., high speed and maneuverability, as exceeding known performance envelopes of U.S. military aircraft and thereby presenting a potential national security threat, if validated. This potential threat prompted the Air Force to call on the Air Materiel Command (AMC), the Service’s Major Command for logistics and procurement from 1946 to 1961, to gather further evidence to assess the validity of the reports. The Air Force emphasized that there was an “imperative need” for such evidence to enable appropriate countermeasures. The stated urgency of this request reflects the strategic environment of the early Cold War, a period characterized by heightened national defense concerns amid rapid global advancements in aerospace design and development. In framing the call for an investigation, the Air Force noted that sustained public interest and persistent inquiries from the press may eventually require an official statement in response. AMC’s investigation found that observers were generally not mistaken when reporting that they had seen an airborne object, but that their characterizations of those objects as unusual was likely a reflection of the “limits of their personal experience.” It identified “a great many” of the objects reported with a rounded appearance as “weather or upper air scientific balloons of some type.” It also identified several cases in which the reported objects were most likely celestial phenomena, such as Venus. AMC found that a small number of reports lacked a “reasonable everyday explanation,” but that “so far, no physical evidence of the existence of the unidentified sightings has been obtained.” AMC expressly considered whether the phenomena may have been “vehicles from another planet,” but found no evidence supporting such an origin. Ultimately, AMC found that “there is as yet no conclusive proof that unidentified flying objects, other than those which are known to be balloons, are real aircraft.” In light of these findings, AMC recommended that the Department of War should avoid publicly commenting on the subject of “flying discs.” Responding to the Air Force’s anticipated concerns regarding public interest in the subject, AMC recommended that the Department should reply in terms that minimize the investigation’s inconclusive findings, focusing on positive determinations in cases assessed to be weather balloons and celestial phenomena.

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Basic ltr fr -Hq USA.F, 3 Nov 48 to CG, AMC, "Flying Object Incidents in
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the United States"
1st Ind MCIAT/ABD/amb
Hq AMC, Wright-Patterson Air Force Base, Dayton, Ohio . 8 Nov 48
TO, Chief of Staff, United States Air Force, Washington 25, D. c., ATTNs
AFOIR
1. In attempting to arrive at conclusions as to the mture of uniden
tified .flying object incidents in the United States, this Command ha.a me.de
a study of approximately 180 such incidents . Data derived from initial re
ports have been supplemented by .further information obtained from check
lists submitted by mail, from interrogations of other field agencies, and
by personal investigation by personnel of this Command in the case of in
cidents that seem to indicate the possibility of obtaining particularly
significant information.
2. The objects described fall into the following general classifica
tion groups, according to shape or physical configuration,
a. Flat disc of circular or approximately o:l.rcular shape .
b. Torpedo or cigar shaped aircraft, with no wings or fins visible
in flight.
c. Spherical or balloon shaped objects.
d. Balls of light with no apparent form attached.
3. Some of the objects sighted have definitely been identified, upon
further investigation, as weather or upper air scientific balloons of some
type . A. great many of the round or balloon shaped objects indicated in
paragraph 2c above are probably of the same nature, although in most cases,
definite confirmation of that fact has been impossible to obtain.
4 . Some of the objects have been identified as beiilg astro - physical
in nature . For example , in daylight sightings, the planet Venus has been
reported as a round, silvery object at extremely high altitude . Action is
being taken to obtain the services of a prominent astro-physicist as a oon•
sultant, to study all of the incidents to determine l'lhether some can be
identified as meteors, planets or other manifestations of astral bodies .
s. Arrangements for accomplishing a study of the psychological problans
involved in this project are being made in coordination with the Aero-Medical
Laboratory at this Headquarters . The possibility that some of the sightings
are halluoir:a tions, optical illusions or even deliberate hoaxes has been con-
., sidered. ~ 1/cf
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l Jo~-.t T-73017