Project Blue Book Declassified: The Mantell Incident

“Each wave of sightings adds to the accumulation of reports which defy analysis by present methods... An investigative process in depth is necessary here if, after twenty years of confusion, we want some answers.” - J. Allen Hynek

On January 7th, 1948, Kentucky National Air Guard pilot Captain Thomas F. Mantell tragically died in the crash of his F-51D Mustang fighter near Franklin, Kentucky, after being sent in pursuit of an unidentified flying object.

U.S. Air Force’s Project Blue Book lead investigator Captain Edward J. Ruppelt wrote of the incident in his 1958 definitive book, The Report On Unidentified Flying Objects that the Mantell crash was one of the three “classic” UFO cases in 1948 – including the Gorman Dogfight, and the Chiles-Whitted Encounter, that would help define the UFO phenomena in the public eye, and convince Air Force intelligence that UFOs were real. Historian and former associate professor at Temple University, David M. Jacobs argued that “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” 

On January 7th, 1948, Godman Army Air Field at Fort Knox, Kentucky, received a report from the Kentucky Highway Patrol of an unusual aerial object near Madisonville, Kentucky. Reports of a westbound unidentified circular object, measuring 250-300 feet in diameter were received from Owensboro and Irvington as well.

At 1:45 PM, Sergeant Quinton Blackwell as well as two other witnesses confirmed seeing a white object from their position in the control tower at Fort Knox. Base Commander Colonel Guy Hix, also reported an object he described as “very white” which “appeared to have a red border at the bottom…” and “remained stationary seemingly, for one and a half hours.”

Eyewitnesses at Clinton County Army Air Field in Ohio described the object “as having the appearance of a flaming red cone trailing a gaseous green mist” and observed it for about 35 minutes. Another observer at Lockbourne Army Air ield in Ohio described seeing the object as “it came to very near the ground, staying down for about ten seconds, then climbed at a very fast rate back to its original altitude, 10,000 feet, leveling off and disappearing into the overcast heading 120 degrees. Its speed was greater than 500 mph in level flight.”

At the time, four F-51D fighters of the 165th Fighter Squadron Kentucky Air National Guard – one piloted by Captain Thomas F. Mantell, were deployed in the air to investigate the object. Blackwell was in radio communication with the pilots, one of which got low on fuel and had to return quickly to base. The other two pilots accompanied Mantell in a steep pursuit of the object. They reported seeing the object but described it as too small that they could not identify any features to it. Air controllers suggested that the pilots should level their altitude and try to get a better visual on the object.

The two pilots, Lieutenant Albert Clements and Lieutenant Hammond called off their pursuit after reaching 22,500 feet altitude due to low oxygen supply, but Mantell, however, continued to climb above 25,000 feet. At this point, Mantell reportedly blacked out from lack of oxygen and his fighter began spiraling down towards the ground until it crashed on a farm south of Franklin, on Kentucky’s border with Tennessee.

A Fireman later pulled Mantell’s body from the wreckage. His seat belt was shredded and his wristwatch had stopped at 3:18 PM, which marked the time of his crash. Meanwhile, by 3:50 PM, the UFO was no longer in sight to observers at Godman Army Airfield.

The Mantell incident was immediately reported by newspapers around the nation and received significant public attention. A number of sensational rumors and speculations also circulated about the crash including – according to UFO historian Curtis Peebles, claims that “the flying saucer was a Soviet missile”; “It was [an alien] spacecraft that shot down [Mantell’s fighter] when it got too close”; “Captain Mantell’s body was found riddled with bullets”; “the plane had completely disintegrated in the air”; “the wreckage was radioactive” etc. No evidence, however, ever surfaced to sustain any of these claims, and Air Force investigation later specifically refuted some of them.

Ruppelt wrote in his report that: “I had always heard a lot of wild speculation about the condition of Mantell’s crashed F-51, so I wired for a copy of the accident report. [It] said that…Mantell’s body had not burned, not disintegrated, and was not full of holes; the wreck was not radioactive, nor was it magnetized.”

The Mantell incident was investigated by the Air Force’s Project Sign which concluded – based on Dr. J. Allen Hynek’s assumption, that the pilot mistook planet Venus for the UFO – because Venus had been in the same place in the sky that the UFO was observed, and was unfortunately killed trying to reach it. An Air Force major who was interviewed by several reporters following the crash “flatly stated that it was Venus.” 

In 1952, the U.S. Air Force ordered Ruppelt to reinvestigate the Mantell incident as part of Project Blue Book – Project Sign’s successor. Ruppelt spoke with Dr. Hynek who, by 1952, concluded that his Venus theory was incorrect because “Venus wasn’t bright enough to be seen” by Mantell and the other witnesses and also due to a considerable haze being present that day which would have further obscured the planet in the sky. Ruppelt also noted that even if Venus was visible, it would have been a “pinpoint of light” as opposed to eyewitness accounts whose “descriptions plainly indicated a large object. None of the descriptions could even vaguely be called a pinpoint of light.”

Ruppelt then began looking for further explanations for the Mantell Incident. He was particularly interested in another suggestion made by Dr. Hynek which stated that Mantell could have misidentified a U.S. Navy Skyhook weather balloon. To further corroborate his claim, Dr. Hynek noted that in Madisonville, “the object was seen through a telescope [and] identified as a balloon by one observer.” Additionally, between 4:30 PM and 4:45 PM, an astronomer at Vanderbilt University “watched an object in the sky…viewed through binoculars, he said it was a pear-shaped balloon with cables and a basket attached.”

However, many were against this idea due to the fact that no particular Skyhook weather balloon could be conclusively identified as being present in the area during Mantell’s pursuit. Despite the objections, Ruppelt found the Skyhook explanation extremely plausible as the balloons were part of a top-secret Navy program at the time, so neither Mantell nor the other observers in the control tower could have been able to identify it. The balloons were also made of reflective aluminium, and measuring about 100 feet in diameter which consistently match the description of the eyewitness accounts. But this was never proved, as Ruppelt wrote:

“Somewhere in the archives of the Air Force or the Navy there are records that will show whether or not a balloon was launched from Clinton County AFB, Ohio, on January 7, 1948. I never could find these records. People who were working with the early skyhook projects ‘remember’ operating out of Clinton County AFB in 1947 but refuse to be pinned down to a January 7 flight. Maybe, they said. The Mantell Incident is the same old UFO jigsaw puzzle.”


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