On September 23, 1947, Lt. Gen. Nathan F. Twining, commanding Air Materiel Command at Wright Field, sent Brig. Gen. George Schulgen an official opinion on "Flying Discs" that treated the reports as a technical intelligence problem rather than only press rumor or witness confusion.12
Origin
The memo began with an Air Staff request to Air Materiel Command specialists: Twining wrote that AC/AS-2 had furnished interrogation reports, and that T-2 intelligence, the Aircraft Laboratory, Engineering Division T-3, the Air Institute of Technology, and aircraft, power-plant, and propeller laboratory personnel produced the command opinion in conference.12
The memo followed the first 1947 flying-disc wave and a short period of FBI-Army Air Forces coordination; the FBI later summarized that its first UFO-related investigations began in the summer of 1947, and that the Bureau issued a July 30, 1947 notice directing field offices to cooperate with Army Air Forces Intelligence on flying-disc reports.3
Who
Twining signed the memorandum as Lieutenant General, U.S.A., Commanding, and addressed it to the Commanding General, Army Air Forces, attention Brig. Gen. George Schulgen of AC/AS-2.12
The memo identified its evidence base as AC/AS-2 interrogation reports plus preliminary studies by Air Materiel Command intelligence and aircraft engineering groups at Wright Field.12
What it said
The memo's central finding was that the reported phenomenon was "something real and not visionary or fictitious," while the same section also allowed that some incidents might be natural phenomena such as meteors.12
It summarized the reported objects as disc-like or elliptical, light-reflecting, usually without trails or sound, sometimes in formations, and estimated to fly above 300 knots in level flight.12
It then framed three analytical possibilities: an unknown domestic high-security project, inadequate physical proof because no crash exhibits had been recovered, or a foreign propulsion development outside U.S. knowledge.12
How evolved
The recommendation mattered because Twining asked Headquarters, Army Air Forces to assign priority, classification, and a code name for a detailed study, circulate complete data to the Army, Navy, Atomic Energy Commission, Joint Research and Development Board, Air Force Scientific Advisory Group, NACA, RAND, and NEPA, and require a preliminary report in 15 days followed by 30-day reports as the investigation developed.12
Air Materiel Command's 1949 Project Sign technical report shows the new study lineage at Wright-Patterson by presenting an Air Materiel Command report titled Unidentified Aerial Objects: Project "Sign" with a February 1949 release date.4
National Archives history later described Project Sign as beginning in December 1947 and ending in February 1949, Project Grudge as Sign's scaled-down continuation, and Project Blue Book as the March 1952 to December 1969 successor that became the longest-running Air Force UFO investigation.5
NARA's Project Blue Book records page says Blue Book was declassified, transferred to National Archives custody, and closed in 1969, while the Air Force fact sheet records 12,618 reports and 701 unidentified cases from 1947 to 1969.67
AARO's 2024 Historical Record Report likewise places Project Sign, Project Grudge, and Project Blue Book in the official U.S. government UAP investigation lineage, describing Blue Book as established in March 1952 and terminated on December 17, 1969.8
In that lineage, the Twining memo matters as the point when senior Air Materiel Command leadership converted scattered flying-disc reports into a structured intelligence requirement whose assumptions carried into Project Sign, then Grudge, and finally Blue Book.12458