Air Force hunted national security threats across nine timed radar film rolls
By June Hargrove ·
Witness names remained secret while the Air Force tracked radar responses from Macao to Bermuda to determine if unidentified flying objects threatened national security.
December 1947. The paper trail begins near Mt. Rainier, Washington, with alleged sightings of flying saucers. In response, the Air Force—tasked with the air defense of the United States—established Project Sign. According to the US National Archives catalogue entry for Project "BLUE BOOK" (NAID 542184), the initial purpose of Project Sign was to determine whether these unidentified flying objects (UFOs) constituted a threat to national security.
Mt. Rainier, 1947
The administrative history of the project is a study in shifting labels and changing command structures. The catalogue entry records that documentation for the effort was managed by the Aerial Phenomena Branch of the Foreign Technology Division (FTD), Air Force Command (AFSC). The project underwent two significant name changes before it became the household name it is today. In 1948, the designation shifted to Project Grudge. By 1952, it became Project Blue Book, though its formal title was the Aerial Phenomenon Group.
Throughout these transitions, the organizational oversight of the files moved through various departments. Prior to 1951, the records were handled by the Intelligence Department of Air Material Command. From 1951 through 1961, the FTD was designated as the Aerospace Technical Intelligence Center, operating under the Assistant Chief of Staff Intelligence (ASC/l) at HQ USAF. This chain of custody continued until December 1969, when the Secretary of the Air Force canceled the UFO function entirely.
Aerial Phenomenon Group
The scope of the project's data collection was broad, drawing from three primary sources. The file's catalogue entry notes that sightings were recorded by the military, by groups, and by individuals. In the case of the individual witnesses, the record explicitly states that their names were not released.
Of particular interest to the records is the evidence captured on film. The catalogue entry lists a wide array of locations where film records of alleged sightings were made. These include domestic sites such as Tulsa, Oklahoma; Binghamton, New York; Snohomish, Washington; Montville and Sandusky, Ohio; and several Air Force bases, including Fairchild (Washington), Olmsted (Pennsylvania), Keesler (Mississippi), and Edwards (California). The reach extended beyond the contiguous United States to include Almogordo, New Mexico, and international locations, specifically Australia and Naha, Okinawa.
Beyond the visual sightings, the archival description highlights a more technical subset of data. There are nine rolls of film specifically documenting "timed radar responses." While visual sightings were scattered across the globe, these radar responses were pinned to a different set of coordinates: Wichita, Kansas; Macao, China; Edwards AFB, California; Bermuda; Duluth, Minnesota; and the Queen Charlotte Islands, Canada.
Nine Rolls of Film
For those auditing the evidence, the catalogue entry mentions the existence of a reference set for these records. This set consists of either contact sheets or positive rolled film, providing a secondary layer of verification for the original reels.
While the primary catalogue entry provides the framework for the project's lifespan and its geographic reach, the National Archives maintains related series that expand the scope of the record. These include a "List of Sightings" maintained from 1947 to 1969—passing from the Technical Intelligence Division to the Air Technical Intelligence Center and finally to the Project Blue Book Office. There is also a separate series dedicated to "Project Bluebook Artifacts," containing physical items submitted in relation to the case files investigated by the USAF between June 1947 and December 1969.
As a radar officer, I look at the mention of "timed radar responses" and see the gap between a visual anecdote and a sensor hit. The catalogue entry tells us the film exists and where it was shot, but it does not describe the contents of those nine rolls or the nature of the responses captured in Macao or Bermuda. It simply lists them as assets of the Aerial Phenomena Branch.
The project's formal end came in December 1969. The records stop there, leaving the reference set of contact sheets and the nine rolls of radar film as the remaining physical ledger of the Air Force's two-decade search for a threat to national security.