On January 7, 1948, 25-year-old Captain Thomas F. Mantell, a Kentucky Air National Guard pilot, died in the crash of his P-51 Mustang fighter plane near Franklin, Kentucky, United States, after being sent in pursuit of an unidentified flying object (UFO). The event was among the most publicized early UFO incidents.

Later investigation by the United States Air Force's Project Blue Book indicated that Mantell may have died chasing a Skyhook balloon, which in 1948 was a top-secret project that he would not have known about. Mantell pursued the object in a steep climb and disregarded suggestions to level his altitude. At high altitude he blacked out from a lack of oxygen; his plane went into a downward spiral and crashed.

In 1956, Air Force Captain Edward J. Ruppelt (the first head of Project Blue Book) wrote that the Mantell crash was one of three "classic" UFO cases in 1948 that would help to define the UFO phenomenon in the public mind, and would help convince some Air Force intelligence specialists that UFOs were a "real" physical phenomenon. Ruppelt's other two "classic" sightings in 1948 were the Chiles-Whitted UFO encounter and the Gorman dogfight.Historian David M. Jacobs argues the Mantell case marked a sharp shift in both public and governmental perceptions of UFOs. Previously, the press often treated UFO reports with a whimsical or glib attitude reserved for silly season news. Following Mantell's death, however, Jacobs notes "the fact that a person had died in an encounter with an alleged flying saucer dramatically increased public concern about the phenomenon. Now a dramatic new prospect entered thought about UFOs: they might be not only extraterrestrial but potentially hostile as well."

The Kentucky Air National Guard (KY ANG) is the aerial militia of the Commonwealth of Kentucky, United States of America. It is, along with the Kentucky Army National Guard, an element of the Kentucky National Guard.

As commonwealth militia units, the units in the Kentucky Air National Guard are not in the normal United States Air Force chain of command. They are under the jurisdiction of the Governor of Kentucky though the office of the Kentucky Adjutant General unless they are federalized by order of the President of the United States. The Kentucky Air National Guard is headquartered at Louisville Air National Guard Base, and its commander is Brigadier General Warren Hurst, Jr.