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.

MEMORANDUM FOR ?.ECORD
18 December 1947
FROBLEP! :
1 . To prepare for signature of the Director of Intelligence an
R&R for the Director of Research and ~velopment outlining availabl e
information and recommendations concerning problems proposed by
11flying discs . u
FACTS AND DISCUSSION :
2 . At the request of the Chief, Air Intelligence Di.vision, an
earlier memorandum dated 6 October 1947, Subject: 11Recommendations
Relative to Unidentified Flying Objects, 11 was reanalyzed and rewritten
as a memorandum .
3 . This memorandum together with a letter f r om Headquarters,
Air Materiel Command, Subject: 11AJJC Opinon Concerning •Flying Discs • , 11
dated 23 September 1947, were attached to an R&R addressed to the
Di.rector of Research and Development . Note was made in this R&R that
the Di.rector of Intelligence concurred with the recommendations of
AMC concerning a specific project to study the ttfJ,.ying disc n situation .
ACTION:
4 . R&R forwarded for signature of Uajor General MacDonald .
COO!IDINATION:
Colonel J . F . Olive, Chief, Air Intelligence Division - Ext . 2542
Lt. Colonel J . E. Thomas, Offensive Air Branch - Ext . 6625