Unidentified Flying Objects (UFOs) and Air Force Project Blue Book
From June 1947 through December 1969 the Air Force was primarily responsible for investigating unidentified flying object (UFO) phenomena. Investigations were conducted by the Air Technical Intelligence Center (ATIC) at Wright-Patterson AFB, Ohio until Dec. 17, 1969.
All records of these investigations (known as Project Sign, 1947-1949, Project Grudge, 1949-1952, and Project Blue Book, 1952-1969, were retired to the National Archives and Records Administration and are available to the public on archives microfilm publication T1206 (94 rolls of 35 mm film).
You might also wish to read The Roswell Report: Fact Vs. Fiction in the New Mexico Desert, by Richard L. Weaver and James McAndrew, which was published by the Headquarters United States Air Force through the U.S. Government Printing Office, Washington D.C. in 1995.
If you are interested in a UFO incident after 1969 that you think involved the Air Force, you will have to identify the unit or organization involved and direct your inquiry to the appropriate records manager for that unit.