Captain Thomas F. Mantell was an experienced Kentucky Air National Guard pilot and at 25 years of age a veteran of World War II (awarded the Distinguished Flying Cross and Air Medal w/3 OLCs for heroism) with a total recorded flight history of over 2,000 hours.
At 2:45 p.m. on January 7, 1948, he along with three other pilots were instructed to approach an Unidentified Flying Object observed by a number of witnesses in the skies above Kentucky. He crashed shortly thereafter, his shattered wristwatch stopped at 3:18 the time of impact.
The episode apparently began at around 1:20 p.m. when control tower operators at Godman Army Airfield received a call from the Kentucky State Highway Patrol of an unusual object in the skies near Maysville, other reports (of a white, round westerly moving object 250 to 300 feet in diameter) were also received from Owensboro and Irvington.
At
1:45 p.m. the object was sighted from Godman itself, and shortly
thereafter four P-51 Mustangs already airborne (one piloted by Mantell,
officer commanding) were ordered to close. One pilot low on fuel broke
off almost immediately, but the other two accompanied Mantell in almost
vertical pursuit. At 22,500 feet (6,900 meters) Lieutenants Clemons and Hammond broke off the chase. Mantell, however, seemingly obsessed continued to climb until apparently blacking out from hypoxia at 25,000 plus feet (7,600 meters). His plane was observed to stall before spiraling earthward, crashing shortly thereafter on a farm near the Tennessee-Kentucky state line.
Within a short time the object disappeared southward into Tennessee and the rumors began ( a government cover-up was under way, the plane had been shot down by a UFO, the pilot’s body was riddled by holes etc). [1]
Explanations government and otherwise:
Project Sign, a study of the UFO phenomenon by the U.S. Air Force during the years 1947 and 48 failed to reach a conclusion [2] while other investigators ruled Mantell was chasing the planet Venus.
The object was a balloon, quite possible in view of the multiple sightings with common or similar descriptions:
From astronomer Dr. Carl K. Seyfert at approximately 4:30 p.m. forty five miles away in Nashville, Tennessee, as filed from Wright Field in Ohio, that Dr. Seyfert . . . had spotted an object SSE of Nashville that he had identified as a pear shaped balloon with cables and a basket attached, moving first SSE, then W, at a speed of 10 miles per hour at 25 thousand feet. This was observed between 16:30 and 16:45. [3]
From the January 8 Nashville Tennessee Banner. . . . Two Hopkinsville aviators, Jimmy Garnett and Bill Crenshaw, investigated the object by plane and identified it as a "free weather balloon" (there were no instruments attached to it). Telescope observers here and at Franklin, Columbia and Clarksville also identified the object as a balloon. As well as. . . . At Madisonville, Ky., where Hugh Clark and Thomas Gant observed what they believed was the same balloon from a plane, the Weather Bureau surmised that it might have been one of 21 weather observation balloons sent up by Northwestern University at Evanston, Ill. [4]
And as for Mantell himself, though an experienced pilot, he was new to the P-51 Mustang, its idiosyncrasies and rate of climb (the afore consistent with the official opinion that he blacked out at altitude and lost control of the aircraft).
[1] There is some speculation that a Skyhook (a balloon capable of reaching extremely high altitudes and used to provide a stable platform for a wide variety of top secret research equipment) possibly launched from either Clinton County, Ohio, some 150 miles (240km) away or from Camp Ripley, Minnesota, 750 miles (1200km) away might have been the unidentified object, and that the Air Force not wishing to be implicated in, or held responsible for, the death of an Air National Guard pilot did attempt a cover-up/misinformation campaign.
[2] Mantell’s UFO encounter is still listed as “undetermined” by the U.S. Air Force.
[3] Seyfert said he originaly thought the object to be Venus, sometimes bright enough to be seen in daylight, then a comet.
[4] Skyhook/Mogul balloons, highly classified at the time, were in all probability unidentifiable as such by either civilian authorities or regular U.S. Air Force personnel of the day.