DOW-UAP-D100

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

PDF
Download PDF at war.gov (opens in a new tab)Official copy from the releasing agency

AI-generated content. The AI summary and topic tags on this page are machine-generated and may contain errors. They are not a verified assessment of the original material. How this is made

A declassified document regarding "Flying Object Incidents in the United States."

Preview description (machine-generated): A declassified document regarding "Flying Object Incidents in the United States."

Official description

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.

Reproduced verbatim from the releasing agency.

AI summary

This file contains U.S. Government memoranda and correspondence regarding 'Project Sign,' a 1948 U.S. Air Force initiative aimed at investigating reports of high-performance airborne objects. It documents findings that while some sightings may have explanations like weather balloons or celestial phenomena, a small number of reports lacked reasonable explanations, prompting concerns over potential national security implications amid the Cold War atmosphere.

Cite this page

Department of War, “DOW-UAP-D100: Air Materiel Command Report on Unidentified Flying Objects, 1947-1948,” released Aug 7, 2026. PURSUE Files, catalogued by Fringe Index: https://fringeindex.com/documentdump/dow-uap-d100-air-materiel-command-report-on-unidentified-flying-objects-1947-1948. Original: https://www.war.gov/medialink/ufo/release_05/Aug_07/documents/DOW-UAP-D100_Air-Materiel-Command-Report-on-UFOs_1947-1948.pdf