[Project Sign was the seemingly independent outfit of scientists, technicians and intelligence officers assembled by the almost entirely out-of-the-loop USAF to analyse UFO reports received by the Air Force in 1947 from “reliable witnesses such as pilots and scientists.” (UFO: The Government Files, Brookesmith) Ruppelt writes of “ATIC’s top intelligence specialists who had been so eager to work on Project Sign…” (The Report on Unidentified Flying Objects, Ruppelt)]
A need for as much additional information as possible about these craft, their performance characteristics and their purpose led to the undertaking known as U.S. Air Force project SIGN in December, 1947. In order to preserve security, liason between SIGN and Majestic-12 was limited to two individuals within the Intelligence Division of Air Materiel Command whose role was to pass along certain types of information through channels. SIGN evolved into project GRUDGE in December, 1948. The operation is currently being conducted under the code name BLUE BOOK…
(Page 005 of the 1952.11.18 Eisenhower briefing)
On 30 December 1947, General Twining‘s recommendation of the previous September became reality. Called Project Sign, the full-time UFO research team was to be part of AMC, based at Wright Field (now Wright-Patterson AFB) in Dayton, Ohio. Its security classification was the lowest grade, restricted, and it had 2a priority (the highest was 1a).
(UFO: The Government Files, Brookesmith)
Twining‘s suggestion [in the memo of 1947.09.23] was endorsed by Schulgen; on 1947.12.30 the Chief of Staff at the Air Force, Major General Craigie, approved the project and ordered the creation of Project Sign. It was to be based at Wright Patterson Air Force Base at Dayton, Ohio (where the Roswell wreckage had been flown), and coordinated by ATIC…
(The Complete Book of UFOs, Randles and Hough)
Following the Arnold incident, the Air Force was given the responsibility of investigating UFO reports from the United States, first as Project Sign (also called Saucer), then Grudge, and finally Blue Book. Usually understaffed and underfunded, the Air Force program functioned more like a public relations office than a scientific investigation, according to the late astronomer J Allen Hynek.
(paranetinfo.com – site now defunct)
[Sign published its Estimate of the Situation in late 1948 and sent it to Chief of Staff Hoyt Vandenberg, who rejected its conclusion that the UFOs represented alien technology.]
It was only after 1947 that UFO reports were studied in any depth. The USAF, which had an obvious interest in any aerial craft that might pose a threat to national security, began by setting up an investigative team under the code-name Project Sign to research the subject. It commenced its work by looking into the 122 flying saucer reports received by the Air Force during 1947. Of these, 110 were identified as aircraft, stars and so on, and twelve remained unidentified.
Some of Sign’s personnel, including director Robert Sneider, favored the extraterrestrial hypothesis as the best explanation for UFO reports. They prepared the Estimate of the Situation arguing their case. This hypothesis was ultimately rejected by high-ranking officers, and Project Sign was dissolved and replaced by Project Grudge…
SIGN evolved into project GRUDGE in December, 1948.