★Historically significant

This is the original April 1948 Project Sign initial progress report — one of the earliest official USAF analytical summaries of UFO sightings — submitted directly to the Chief of Staff by AMC's Chief of Intelligence Colonel H. M. McCoy, consolidating 100 incidents including the Godman Field series and the first known official photographic analysis of a UAP photograph (Incident #40).

DOW-UAP-D097, Project Sign Progress Report, 1948

Department of WarPDFAnalysisCONFIDENTIALNo redactionsPURSUE Release 4

8/10

significant, well-sourced

UAP Insight significance score

Location: Various
Incident date: 1948
Witnesses: Multiple witnesses
Released: July 10, 2026

UAP Characteristics

◉ DiscHoveringErratic movementHypersonic speedHigh-G maneuverLuminousColor change

Evidence Types

VisualPhotosTestimony

Government Programs Referenced

Official Conclusion

Insufficient data for positive identification; low aspect ratio aircraft construction assessed as technically feasible explanation

Official Description

This file contains an initial report from the Air Materiel Command regarding Project Sign. Project Sign was a 1948-1949 U.S. Air Force program to investigate the nature and origin of unidentified flying objects (UFO). The report details 100 UFO sightings from 1947-1948. The file also contains an article excerpted from “The Aeroplane,” an aviation-focused periodical magazine published between 1911 and 1968, titled “The Biology of the Flying Saucer.”

Key Findings

→Objects were described as oval, disc, or saucer-shaped in 31 of the 100 reported incidents, with reported sizes ranging from a 25-cent piece to 250 feet in diameter and up to the bulk of six B-29 airplanes.
→Observed behaviors included high rates of climb, hovering for considerable lengths of time, and speeds ranging from very slow to supersonic across the 100 incidents.
→Dr. Irving Langmuir of General Electric Research Laboratories concluded that available data was insufficient for positive identification and was reluctant to accept flying discs as a reality.
→AMC headquarters assessed that it was technically possible to construct a low aspect ratio aircraft replicating the appearance and performance of reported flying discs, achievable through boundary layer control.
→Two specific incidents were discredited: Incident #18 was definitively determined to be a hoax perpetrated for publicity and money, and the reporter of Incident #84 was assessed as an excitable person with an exaggerated imagination.

UAP Insight Analysis— AI generated, not official

This is the initial progress report for Project Sign (Project HT-304), dated 23 April 1948, submitted by Headquarters Air Materiel Command (Wright-Patterson AFB) to the USAF Chief of Staff. It consolidates 100 UFO incident reports from mid-1946 through early 1948, providing tabulated data on locations, observer occupations, object descriptions, maneuvers, speeds, and altitudes. Enclosures include photographs from Incident #40, a photographic analysis memo, and a multi-part article from 'The Aeroplane' periodical on low aspect ratio disc-wing aircraft ('The Biology of the Flying Saucer').

Analyst Notes

The vast majority of the 100 incidents are single-witness visual observations with no sensor corroboration. The document itself discredits two incidents (Incident #18 as a confirmed hoax, Incident #84 as an unreliable witness). Many observer occupations are listed as 'not stated,' reducing traceability. AMC explicitly notes that Dr. Langmuir found existing data insufficient for identification. The inclusion of a published magazine article ('The Biology of the Flying Saucer') as an official enclosure suggests investigators were actively exploring conventional aeronautical explanations. No physical evidence was recovered from any incident.

Extracted Entities

People

General L. C. CraigieH. M. McCOY (Colonel, USAF, Chief of Intelligence)Dr. Irving LangmuirMr. Rhoades (Incident #40 photographer)A. R. Weyl (author of 'The Biology of the Flying Saucer' article)Charles H. Zimmermann (NACA researcher)G. Tilghman RichardsCedric LeeGordon England

Agencies & Organizations

Headquarters Air Materiel Command (AMC), USAFDirector of Intelligence, USAFGeneral Electric Research LaboratoriesCivil Aeronautics Authority (CAA)

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AI analysis by claude-sonnet-4-6 · July 20, 2026