Project Sign
Project Sign was the first official United States Air Force investigation into unidentified flying objects (UFOs), created in 1948 following Lieutenant General Nathan Twining's assertion that flying discs were "real and not visionary or fictitious" in a letter to Air Force Commanding General George Shugen. The program investigated military and civilian UFO reports during the late 1940s, including the famous Gorman Dogfight of October 1, 1948.
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Establishment and Authority
Project Sign was established with high-level institutional mandate and oversight. All Project Sign reports were required to be sent to three major organizations: the Army and Navy Research and Development Board, the USAF Scientific Advisory Board, and the Atomic Energy Commission. This distribution requirement indicated the serious multi-agency concern about the UFO phenomenon at the highest levels of government and military leadership.
Gorman Dogfight Investigation
Project Sign conducted a thorough investigation of the Gorman Dogfight incident involving Second Lieutenant George F. Gorman's 27-minute aerial pursuit of an unidentified luminous object over Fargo, North Dakota on October 1, 1948. Investigators interviewed Gorman and other witnesses, including air traffic controller L.D. Jensen.
As part of the investigation, Project Sign tested Gorman's P-51 Mustang for radiation. The aircraft was measurably more radioactive than other fighters, initially leading investigators to conclude the craft had flown close to an "atomic powered object." However, further analysis attributed this to reduced atmospheric shielding at the 14,000-foot altitude Gorman reached during the pursuit.
Project Sign initially rolled out conventional explanations such as weather balloons and jets but found them inconsistent with the evidence. Ultimately, the program concluded that Gorman had either chased a lit weather balloon or the planet Jupiter, and that the object's fantastic maneuvers were an illusion based on his frame of reference — a conclusion that contradicted sworn testimony from both Gorman and Jensen.
Legacy
Captain Edward J. Ruppelt, who later directed Project Sign, Project Grudge, and Project Blue Book, wrote that the Gorman dogfight was one of three classic UFO incidents in 1948 that "proved to Air Force intelligence specialists that UFOs were real." This assessment reflects the institutional stance during Project Sign's operational period, before the Air Force adopted more dismissive positions under subsequent programs.