Mantell UFO incident
On 7 January 1948, 25-year-old Captain Thomas F. Mantell, a Kentucky Air National Guard pilot, died when the P-51 Mustang fighter plane he was piloting crashed near Franklin, Kentucky, United States, after being sent in pursuit of an unidentified flying object (UFO). Pursuing the object in a steep climb and disregarding suggestions to level his altitude, Mantell lost consciousness at high altitude from lack of oxygen; his plane went into a downward spiral and crashed.