Presentation by Captain Edward J. Ruppelt, March 26, 1952 — Department of War Audio

Incident Overview

On March 26, 1952, in Boston, Massachusetts, the Department of War preserved an audio recording that was declassified and published on September 18, 2026 as part of the sixth tranche of the Department of War’s Presidential Unsealing and Reporting System for UAP Encounters (PURSUE).

What the government released

This audio file records a March 1952 presentation by Captain Edward J. Ruppelt, outlining the U.S. Air Force’s reorganized investigation into unidentified flying objects (UFOs). The presentation previews prospective technical methodologies, such as diffraction-grating photography and radar-scope synchronization, that were subsequently incorporated into Project Blue Book, a U.S. Air Force program active from 1952 to 1969 that investigated the nature and origin of UFOs. Ruppelt explains that out of approximately 800 historical cases reviewed by the Air Force, approximately 20% remained unexplained after technical analysis. These unresolved reports were sourced from credible military personnel, commercial pilots, and other qualified technical observers. He highlights geographic report concentrations around sensitive national security and nuclear weapons installations (including Los Alamos, Albuquerque, and Oak Ridge National Laboratories) and notes recurring anomalous characteristics, including silent high-speed flight and radar detections indicating unconfirmed air speeds between 1,000 and 3,500 miles per hour. Emphasizing that the Air Force found no conclusive evidence regarding the nature or origin of the phenomena, Ruppelt underscores the national security need for a systematic physical data collection effort to better evaluate these sightings.

The case in this archive

This record is a primary source for Project Blue Book, written up here at length from the contemporary record. The file and the case history are worth reading against each other: the document is narrower and more cautious than the account that grew up around it, which is usually the point.

Status of the case

This is an archival record, and it should be read as one. It records what a particular office believed, or was willing to commit to paper, on the day it was written — not a present-day finding. The mid-century investigations worked from witness testimony, sparse instrumentation, and the strategic anxieties of the early Cold War, and the great majority of the sightings they catalogued were eventually attributed to aircraft, balloons, astronomical objects, and misidentification. The All-domain Anomaly Resolution Office has made no modern determination about the incidents described here, and the record’s release is not an endorsement of the conclusions inside it. Its value is as evidence of how the United States government investigated the question, and of what it chose to keep.

Sources

• DVIDS asset 1023407
• Department of War UFO Disclosure Portal
• AARO (All-domain Anomaly Resolution Office)
• PURSUE record identifier: DOW-UAP-PR160 (Release 06, September 18, 2026)