Project Sign
From the UAP Encyclopedia, the open encyclopedia of UFO and UAP history · 🏛️ Program or study
Contents 6

| Type | Program or study |
|---|---|
| Also known as | Sign |
| On the Timeline | 4 events, 1947–1956 |
Project Sign, sometimes called Project Saucer, was the U.S. Air Force's first official study of unidentified flying objects, active for most of 1948 at the Air Materiel Command at Wright Field (later Wright-Patterson Air Force Base) in Ohio. It was set up after Gen. Nathan Twining's September 1947 memo calling the flying discs "real", and was succeeded by the more skeptical Project Grudge in early 1949.[1][2]
Origins
During the summer 1947 flying saucer wave, Brig. Gen. George Schulgen of Army Air Forces intelligence asked Air Materiel Command for an evaluation. In a memo dated 23 September 1947, its commander, Lt. Gen. Nathan Twining, replied that the phenomenon reported was "something real and not visionary or fictitious", described the objects' reported features, and recommended a formal investigation. Project Sign was created in response and began work in early 1948.[1][3]
Work
Sign's purpose was to collect, evaluate and share within government all information on UFO sightings, on the premise that they might threaten national security. Its period included major cases such as the January 1948 death of Kentucky Air National Guard pilot Thomas Mantell while chasing an unidentified object and the July 1948 sighting of a cigar-shaped craft by Eastern Air Lines pilots Clarence Chiles and John Whitted.[1][4] Astronomer J. Allen Hynek was hired as a consultant to suggest astronomical explanations. In May 1949, Sign officers also examined the remains of inventor Jonathan Caldwell's homemade disc-rotor aircraft found on a Maryland farm, concluding it could not explain the reports.[1]
The "Estimate of the Situation"

According to Edward Ruppelt's 1956 book The Report on Unidentified Flying Objects, Sign staff wrote a top-secret "Estimate of the Situation" in 1948 concluding that some UFOs were interplanetary spacecraft. Ruppelt said it was sent to Air Force Chief of Staff Gen. Hoyt Vandenberg, who rejected it for lack of physical proof, and that copies were later destroyed.[1][4] No copy has ever been found. In 1966 Representative Mendel Rivers told Congress that no such estimate had existed, and Popular Mechanics has described it as probably more myth than fact; some historians, however, believe indirect evidence supports Ruppelt's account.[1][5]
End and legacy
Sign's February 1949 report said some UFOs appeared to be real aircraft but that there was not enough data to determine their origin, and recommended continued investigation; a summary was released to the press in April 1949. By then the project had been replaced by Project Grudge, which attributed reports to misidentification, hysteria and hoaxes. The shift is often seen as the start of the Air Force's long effort to explain away UFO reports, which continued through Project Blue Book until 1969.[1][6]
On the UAP Timeline

- Twining memo (1947) (23 September 1947) — Gen. Nathan Twining writes that the flying discs are real and could be a secret U.S. or Soviet project.
- Research and Development Board dismisses the discs (1948) (31 January 1948) — A Pentagon research board publicly dismisses flying saucers as mirages and mass self-hypnosis.
- Ruppelt held back before the Robertson Panel (9 December 1952) — An Air Force colonel stops Blue Book's Edward Ruppelt from sharing strong cases with the CIA before the Robertson Panel.
- Ruppelt's account of the Estimate of the Situation (February 1956) — Edward Ruppelt writes he once saw a top-secret 'Estimate of the Situation' on UAP.
References
- Project Sign — Wikipedia · en.wikipedia.org · archived copy
- Gerald Haines, "CIA's Role in the Study of UFOs, 1947–90", Studies in Intelligence (1997) · web.archive.org · archived copy
- "The Twining letter" (23 Sep 1947) — Roswell Files · roswellfiles.com · archived copy
- Edward J. Ruppelt, The Report on Unidentified Flying Objects (1956) — Internet Archive · archive.org · archived copy
- MJ Banias, "50 Years Ago, the Air Force Tried to Make UFOs Go Away. It Didn't Work", Popular Mechanics (2019) · popularmechanics.com · archived copy
- "Project Sign – Report of February 1949" (U.S. Department of Defense, archived) · web.archive.org · archived copy
This page was last edited on 29 October 2026. Articles are written in our own words from the sources listed under References; disputed claims are attributed to the people who made them.
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