Project Sign progress report
Progress report of Project Sign, the US Air Force's first formal investigation into unidentified aerial phenomena. Dated December 1948. Released through PURSUE Release 04 on July 10, 2026 as DOW-UAP-D097. The immediate institutional precursor to Project Grudge and Project Blue Book.
This case predates PURSUE, so the primary record was never centrally digitized. The source links below point to the best public records available: original investigators, primary reporting, and diagnostic-friendly secondary analysis. For PURSUE-era cases, mirrored files render inline further down.
Mirrored files
1 file for this case, served from our first-party mirror.
DOW-UAP-D097 · pdf · Release 04
Provenance metadata
None of the 9 structured provenance fields were disclosed in this release. That is a gap in the source, not on our end.
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- Coordinates
- Altitude
- Sensor detail
- Encounter duration
- Witness count
- Operational context
- Weather / visibility
- Chain of custody
- Classification
Official description
DOW-UAP-D097: Project Sign progress report authored by the Air Materiel Command's Technical Intelligence Division at Wright-Patterson AFB. Dated December 1948. The report summarizes the first eighteen months of what was then classified as Project SAUCER (public name) or Project Sign (internal name), covering approximately 200 case investigations conducted January through November 1948.
Editor's context
Project Sign was formally established December 30, 1947 by USAF General Nathan Twining, three months after the Kenneth Arnold sighting and six months after the Roswell Army Air Field press release. Sign's charter was to determine whether unidentified aerial objects represented a foreign-adversary technology threat. The December 1948 progress report is the earliest substantive institutional US assessment of the phenomenon and the direct ancestor of Project Grudge (1949-1951) and Project Blue Book (1952-1969).
Prevailing explanation
What scientists and analysts generally think
The 1948 Sign report concluded that the accumulated case evidence was consistent with a mixture of misidentified natural phenomena, misidentified experimental aircraft, and psychological effects. It explicitly considered but rejected the interplanetary hypothesis on the grounds of insufficient evidence. This dispositional pattern was carried forward with modifications through Grudge and Blue Book and is the direct antecedent of the modern AARO methodology.
In the margins
Transcribed redactions, stamps, and handwritten markings, the paratext of the file. Often the most human part of a declassified document, and worth reading on its own.
- Stampp. coverAIR MATERIEL COMMAND, TECHNICAL INTELLIGENCE DIVISION
- Stampp. coverPROJECT SIGN / PROJECT SAUCER
- StampDECLASSIFIED PER PURSUE, July 10, 2026
- AnnotationConvening authority: USAF General Nathan Twining, December 30, 1947.
- AnnotationReporting period: January through November 1948, approximately 200 case investigations.
- AnnotationDirectly succeeded by Project Grudge (1949-1951) and Project Blue Book (1952-1969).
Cite the primary source
Citations center the originating government agency and link to the official record. This archive is listed as the access point, not the author.
U.S. Department of Defense. "Project Sign progress report." Released via PURSUE program, 2026-07-10. File ID: PURSUE DOW-UAP-D097. https://www.war.gov/UFO/release/04/. Accessed 2026-09-05 via Social Media for Aliens archive, https://socialmediaforaliens.com/files/project-sign-progress-report-1948.
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