On 7 January 1948, 25 year old Kentucky Air National Guard pilot, Captain Thomas F. Mantell, died while in pursuit of an unidentified flying object near Fort Knox. The so-called Mantell Incident is among the most publicised and infamous UFO reports of the early modern era.
The Air Force’s J Allen Hynek suggested he had been chasing a Skyhook weather balloon. Neither scenario explains why Capitan Mantell’s watch had stopped at 3:18pm, while his plane crashed at 3:50.
The official Air Force report was later changed, and the cause of Mantell’s crash remains officially listed as undetermined.
Donald Keyhoe suggested that Air Force officials thought that Mantell may have been shot down by a UFO, but such reports were suppressed.
References
wiki: Mantell_Incident