Project Sign

In early 1948, the newly independent United States Air Force established Project Sign as its inaugural formal effort to evaluate reports of unusual aerial phenomena, growing out of a September 1947 memorandum by Lieutenant General Nathan Twining urging organized scientific study of the sighting wave.

Operations and Analysis

Operating from Wright-Patterson Air Force Base in Ohio, the team compiled case files and conducted technical analyses throughout most of 1948. Their work focused on systematically evaluating the growing number of UFO reports from military and civilian sources.

Key Finding

The project's most consequential output was a classified document known as the 'Estimate of the Situation,' which reportedly concluded that some observed objects could be of extraterrestrial origin.

Rejection and Reorganization

General Hoyt Vandenberg, then Air Force Chief of Staff, rejected the estimate, citing insufficient physical evidence. The project was subsequently reorganized under a more skeptical framework and redesignated as Project Grudge in early 1949.

Elizondo's Account

Elizondo references Project Sign in Imminent as part of the historical lineage of US government UFO investigation programs: Sign (1948) led to Grudge (1949), then Blue Book (1952-1969), before the gap until AAWSAP (2007) and AATIP (2008). He notes that Sign's initial 'Estimate of the Situation' concluded that UFOs were interplanetary — a conclusion that was rejected by Air Force leadership and ordered destroyed.

Project Sign established the template for decades of official US government engagement with UFO phenomena. The rejection of its extraterrestrial hypothesis by senior leadership set a pattern of institutional skepticism that would persist through Blue Book and beyond.