Thomas F. Mantell (born June 30 1922) was a captain in the Kentucky Air National Guard who became the first military pilot known to have died while chasing an unidentified flying object. His death on January 7 1948, during the “Mantell UFO incident,” remains one of the most controversial and tragic cases in UAP history.

On that afternoon, ground observers at Godman Army Airfield (Fort Knox, Kentucky) reported a large, silvery object hovering in the sky. Mantell, flying a P‑51 Mustang, was directed to intercept it. In radio transmissions, Mantell described the object as “metallic … of tremendous size.” Disregarding warnings about his altitude and oxygen supply, he continued climbing to an estimated 25,000 feet, where he lost consciousness from hypoxia. His aircraft entered a steep dive and crashed near Franklin, Kentucky, killing him instantly.

The official Air Force investigation, led by Project Blue Book director Edward J. Ruppelt, later concluded that Mantell had likely been chasing a high‑altitude Skyhook balloon—a top‑secret project unknown to most pilots at the time. However, inconsistencies in witness descriptions and the absence of definitive radar data have kept the case open in the eyes of many UAP researchers. Mantell’s death highlighted the risks military personnel could face when encountering unexplained aerial phenomena and spurred greater caution in future UFO‑related interceptions.