The Mantell Mystery




The past is a foreign country; they do things differently there.

L.P. Hartley, The Go-Between

Back in early 1948, discussion about flying saucers (the term UFO’s wasn’t generally used until around 1952) was reaching the point of hysteria. Newspapers began carrying reports in mid-1947 and by the end of the year, these were being very widely read. The question most people were asking was: What are these things? Were flying saucers really piloted by aliens from outer space? Were they friendly? Or hostile? Or were they secret weapons and part of some dastardly Commie plot to undermine the Free World? (or a cunning Capitalist running-dog ploy to subvert the will of the people, depending on which side of the Iron Curtain you found yourself).

man6Front page of the Rocky Mountain News, July 1947

The one thing that the majority of the public seemed to agree upon was that these strange flying craft were real. Even the US Air Force had carried a confidential, internal evaluation of sightings and concluded by the end of July 1947 that “Something is really flying around.” In these more cynical times, it may be hard to understand that back then, people may have disagreed about just what they were, but relatively few argued that flying saucers didn’t exist at all. The late 1940s was a time when science seemed to offer almost unlimited possibilities but also equal grounds for worrying whether these were grounds for optimism or pessimism. In the West, the Second World War was over, jobs were plentiful and advances in medicine such as antibiotics seemed to offer everyone a longer and more fulfilling life with more time and money for leisure. But we were also becoming aware for the first time of the full horrors of the Nazi regime, supported as it had been by advances in science and technology, and the development of nuclear weapons made an all-out nuclear war between East and West seem only too possible.

man7Poster for Earth vs The Flying Saucers, 1956

Were flying saucers the vehicles of a benevolent and advanced society who had come to Earth to offer advice and guidance? Or war machines which used advanced technology to ensure that they would triumph against the paltry weapons of Earthlings? When a US Air Force officer died in January 1948 while trying to intercept a unknown object, it seemed that we had the answer: Flying saucers were not only real, they were evidently hostile. For many people, the death of Captain Thomas Mantell removed any lingering doubts they may have had about the reality of flying saucers. If these things were real enough to cause a fighter aircraft to crash and kill its pilot, they were something that had to be taken seriously. Before the end of 1948, a high-level US Air Force project team submitted a secret report evaluating the Mantell incident and flying saucer encounters. Their conclusion: Flying Saucers were not only real, they were possibly alien craft of extraterrestrial origin.

“The death of Mantell had had a profound effect on many in the Air Force. A dozen times I was told: “I thought the saucers were a joke-until Mantell was killed chasing that thing at Fort Knox.”

Major Donald Keyhoe, Flying Saucers are Real, 1950.

Officially however, the US Air Force admitted no such thing. When an official report was published on the death of Captain Mantell it reached a conclusion that ruled out any involvement by unknown craft. But the solution provided was so patently silly that even Air Force personnel reacted with incredulity and almost everyone suspected some kind of cover-up. In the years since, a more plausible explanation has developed involving a secret US Navy Project. But even that contains some odd anomalies. This mystery is like an onion –  The more layers you peel away, the more is revealed underneath. So, let’s travel back to the skies over Kentucky in early 1948 and see if we can unravel this mystery.


In early 1948, flying saucers were big news. Pilots had seen odd lights and what might have been strange craft in the skies over Europe during World War Two but these hadn’t been widely publicised. Sightings continued in Europe and America after the war but it wasn’t until June 24th 1947 that a sighting of strange aircraft by Kenneth Arnold in Washington State that this issue was taken up on a large scale by the mass media in the US and elsewhere. Arnold had been searching for a missing Marine Corps aircraft when he reported seeing a flight of nine “peculiar looking aircraft” apparently flying in formation near Mt. Ranier. The craft he reported weren’t circular, he variously described them as shaped like “half a pie pan with a convex triangle at the rear” or “crescent shaped”. However, when he tried to describe their odd, undulating flight pattern to reporters he described them as moving “like speed boats on rough water” or “like a saucer would if you skipped it across the water“. Ignoring Arnold’s description of the shape of these objects, some enterprising reporter with an eye for a good hook dubbed these craft “flying saucers”.

man8Kenneth Arnold with an artist’s impression of one of the not at all circular aircraft he claimed to have seen.

The term captured the popular imagination and the idea that strange, circular craft were flying in the skies over America began to be widely accepted. Other sightings followed in the latter part of 1947 including what was initially reported as the recovery of a crashed flying saucer near Roswell. Many of these incidents reported just the sort of circular craft that Arnold hadn’t seen, but which were inescapably suggested by the term flying saucer. When the first movies began to appear featuring aliens, they were inevitably equipped with futuristic circular craft. The US Air Force became sufficiently concerned about reports of unidentified aircraft over America (some from its own pilots) that it created a small, informal group within the Air Force Directorate of Intelligence to evaluate these sightings. Lt. Col. George D. Garrett, acting Chief of the new group, issued a confidential report in late July 1947 in which he concluded that: “This “flying saucer” situation is not all imaginary or seeing too much in some natural phenomenon. Something is really flying around.

In September 1947 the United States Air Force (USAF) became a separate branch of the US military for the first time – prior to this date it had been part of the US Army as the United States Army Air Force (USAAF). The evaluation of flying saucer reports was clearly within the purview of the new service and by early December the reporting of flying saucer sightings had become so widespread that USAF Chief of Research and Develop­ment General Curtis LeMay, who would later go on to the Chief of Staff for the US Air Force, asked for clarification of the situation. Spurred on by this, the Directorate of Intelligence produced a new evaluation in mid-December which confirmed that flying saucers appeared to be real, were not American, were not operated by any of the Western allies and were not believed to be Soviet in origin. The situation was considered so serious that a formal special project team, codenamed Sign, was created to analyse flying saucer incidents and reports. Project Sign was part of the USAF technical intelligence group based at Wright-Patterson AFB in Dayton, Ohio. The new project (which was generally and informally known as Project Saucer within the US Air Force) was formally initiated on December 30th 1947 under the leadership of Captain Robert R. Sneider. The Project Sign team didn’t have long to wait for their first major incident.

man9Project Sign personnel at Wright-Patterson AFB in 1948

Before we talk in detail about the events of 7th January 1948, I want to provide a couple of clarifications. The information in this section is mainly drawn from US Air Force press releases, newspaper reports, statements given to US Air Force accident investigation officers, records kept by the Project Sign team and other documents relating to the Mantell incident and the subsequent investigation which have been released under the Freedom of Information Act. However, many of these are based on recollections by witnesses, sometimes well after the events in question. For example, there was no recording or formal transcription of radio messages between Godman Tower and Mantells’ flight – each witness told the accident investigation team what they remembered and these recollections don’t always precisely agree. The same applies to timings – no-one was keeping a log of events on that Wednesday afternoon and, other than telephone calls which were formally logged, all timings are based on witness testimony which sometimes fails to agree. And finally, was Captain Mantell flying a P-51 or an F-51 aircraft? This doesn’t actually matter much – the P-51 and the F-51 are actually the same aircraft. The US Air Force changed the designation for fighter aircraft from P (for Pursuit) to F (for Fighter) soon after it was formed as an independent body in September 1947. The formal designation for the aircraft Mantell was flying had changed to F-51 by January 1948 but most people in the Air Force still used the old P-51 designation. In all the contemporary US Air Force documents, Mantell’s aircraft is referred to as a P-51, so that’s what I’ll call it here.

man10A flight of P-51D Mustangs of 165th Fighter Squadron, Kentucky Air National Guard

On Wednesday January 7th, 1948 at approximately 07:20 witnesses on the ground in Edwardsville, Illinois watched as an object “of aluminum appearance without apparent wings or control surfaces” moved across the sky towards the southwest. This object remained visible for about 30 minutes. This sighting was later reported in the local newspaper, the Edwardsville Evidencer and appeared in a US Air Force incident report looking at the Mantell incident.

At around 13:00 several witnesses on the ground in the town of Elizabethtown in Kentucky called in reports to the Kentucky State Police of a large, circular, metallic object of 250-300 feet in diameter following a westbound course. Ten minutes later what appeared to be the same object was reported near Madisonville and a third report placed it over Lexington. Due to the proximity of the reported object to the US Gold Reserve at Fort Knox, the state police notified Fort Knox Military Police who then contacted the office of the Base Commander at Godman Army Airfield, the closest USAF base to Fort Knox. At 13:20 the Base Commander’s office then passed the report on to Technical Sergeant (T Sgt) Quinton A Blackwell, chief operator in the Control Tower at Godman at 13:20. Blackwell contacted Flight Service at Wright-Patterson AFB in Dayton to ask if they had any aircraft in the air which might account for the sighting? Wright-Patterson replied that they did not but requested Godman to verify the sighting. Shortly afterwards Flight Service at Wright-Patterson contacted Godman Tower with details of further ground sightings reported from the towns of Irvington and Owensboro which seemed to be of the same object.

man2Approximate locations of initial reported sightings:

  1. Edwardsville, Illinois, 07:20
  2. Elizabethtown, Kentucky, 13:00
  3. Madisonville, Kentucky, 13:10
  4. Lexington, Kentucky, 13:15
  5. Irvington, Kentucky, 13:25
  6. Owensboro, Kentucky, 13:25
  7. Godman AAF/Fort Knox

Like most other Air Force bases of the period, Godman was not equipped with Radar. Aircraft were tracked visually and contacted via radio. At around 13:45 T Sgt Blackwell, Pfc Stanley Oliver and one other witness in the control tower at Godman saw an object in the air to the south of the airfield. They were unable to identify the object which Oliver later described as looking like “an ice cream cone topped with red” and they called the Detachment Commander, First Lieutenant Orner to the Tower. Lt Orner was also unable to identify the object despite examining it with binoculars. He saw something that looked like “a parachute does with bright sun shining on the top of the silk but there also seemed to be some red light around the lower of it.” At around 14:05 Orner called the base Operations Officer, Captain Carter, who also came to the tower. Captain Carter noted that the object was easily visible to the naked eye and appeared round and white (whiter than the clouds that passed in front of it) and was so bright that it could also be seen through cirrus clouds. At around 14:20 the Base Commander, Colonel Guy F. Hix arrived in the tower accompanied by Lieutenant Colonel Wood and Captain Duesler. Colonel Hix reported seeing a very large, white, umbrella shaped object about one fourth the apparent size of the moon to the south of Godman. The men in the Control Tower studied the object, but none were able to identify it.

At around 14:30 a flight of four aircraft were seen to be approaching Godman from the south. Colonel Hix instructed T Sgt. Blackwell to contact the aircraft. Blackwell did this and learned that this was a flight of four P-51D Mustang aircraft from the 165th Fighter Squadron of the Kentucky Air National Guard on a routine ferry flight from Marietta Army Airfield in Georgia to Standiford Army Airfield Field near Louisville (around 20 miles northeast of Godman). The aircraft were around ten miles southeast of Godman when they were first contacted. The flight was led by Captain Charles Mantell, a 25 year old veteran pilot of World War Two during which he had been awarded both the Distinguished Flying Cross and the Air Medal.

man11Pilots of 165th Fighter Squadron, Kentucky Air National Guard pose in front of a P-51D aircraft in 1947. Captain Thomas Mantell is in the front row, second from the right. On the right of the front row (to Mantell’s left) is Lt. A. W. Clements.

In addition to aircraft NG869 which was being flown by Mantell, the other three aircraft in the flight were NG 737 flown by Lt. B. A. Hammond, NG 800 flown by Lt. A. W. Clements and NG 336 flown by Lt. R. Hendricks. Of these four aircraft, only the aircraft flown by Lt. Clements had a fully operational oxygen system. Hendricks reported to the flight leader that he was low on fuel and he was directed to continue his flight to Standiford Army Airfield. The other three aircraft, led by Mantell, were by this time almost directly overhead Godman Tower and they began a spiralling climb. Approximately five minutes later they levelled off and flew a course of 210°, southwest from Godman and still climbing towards the unknown object. The observers in the Control Tower noted that, as the P-51’s flew towards the object, it appeared to be very large in comparison to the size of the aircraft, perhaps several hundred feet in diameter.


  1. Planned route of Mantell’s flight from Marietta AAF in Georgia to Standiford AAF in Kentucky (and the actual route followed by Hendricks who continued on to Standiford).
  2. Mantell and two other aircraft divert towards Godman AAF.
  3. Mantell and two other aircraft fly a course of 210° from Godman.

Several radios messages passed between Mantell’s flight and the Tower. When the men in the Control Tower gave statements the following day to Air Force accident investigators, each seemed to have a slightly different recollection of what was said. As some researchers have placed great emphasis on what was (or wasn’t) said, here are the radio messages as given in the statements of those present in the Tower on 7th January. It’s also worth noting that many other people were also listening in to these radio communications. The Air Force used something called the Plan 62 intercom system to allow Control Towers and others to communicate in real time. As the events of 7th January unfolded, many other Air Force stations were listening in including, it has been claimed, personnel from Project Sign.

T Sgt Blackwell gave the most complete account of radio messages in his statement of 8th January. He noted that: “About 1445 the flight leader, NG 869, reported seeing the object “ahead and above, I’m still climbing“. To which a wing man retorted, “What the Hell are we looking for”? The leader reported at 15,000 ft that “The object is directly ahead of and above me now, moving about half my speed”. When asked for a description he replied, “It appears metallic object of tremendous size”. At 15,000 ft, the flight leader reported, “I’m still climbing, the object is above and ahead of me moving at about my speed or faster, I’m trying to close in for a better look.” This last contact was at about 1515.” Blackwell also added that as the two other P-51s which had accompanied Mantell passed over Godman on their way back to Standiford NG 800 (Lt. A. W. Clements) reported “It appears like the reflection of sunlight on an airplane canopy“. It’s notable that Blackwell was the only person in the Tower on 7th January who recalled Mantell describing the object as a “metallic object of tremendous size” and Blackwell repeated this when he was interviewed by Project Sign staff later.

man12T Sgt, Blackwell (left) and Colonel Hix.

First Lieutenant Orner had a slightly different recollection. “The flight leader and two other planes flew a course of 210° and in about five minutes sighted the object. At first the flight leader reported it high and about one-half his speed at “12 o’clock”. Shortly thereafter the flight leader reported it at about his speed and later said he was closing in to take a good look. This was the last message from NG869, the flight leader.”

Pfc Stanley Oliver said even less about radio messages in his statement: “We kept in contact with the flight leader for about twenty-five minutes. The last contact we had with the flight leader was when one of his wingmen called and said “What the hell are we looking for?” Flight leader stated had the object in sight and he was going up to see what it was. He said at present he was at 15,000 feet and was still climbing. Those were the last words I believe we heard from him. Other pilots in the formation tried to contact him but to no avail.”

Captain Duesler noted in his statement that: “… the remaining three P-51’s were climbing on the course given to them by Godman Tower towards this object that still appeared stationary. The Tower then advised the Flight Leader to correct his course 5 degrees to the left; the Flight Leader acknowledged this correction and also reported his position at 7,500 feet and climbing. Immediately following the Flight Leaders transmission, another member of the flight asked “where in the hell are we going?” In a few minutes the Flight Leader called out an object ”twelve o’clock high”. Asked to describe this object, he said that it was bright and that it was climbing away from him. When asked about its speed, the Flight Leader stated it was going about half his speed, approximately 180 M.P.H. Those of us in the Tower lost sight of the flight, but could still see this object. Shortly after the last transmission, the Flight Leader said he was at 15,000 ft, and still climbing after “it”, but that he judged its speed to be the same as his. At that time a member of the Flight called to the leader and requested that he “level off”, but we heard no reply from the leader. That was the last message received from any member of the flight by Godman.”

Captain Carter noted that: “One of the planes said he spotted the object at 12 o’clock and was climbing toward it. One of the planes then said, “This is 15,000 ft., let’s level out”. One of the planes, at this point (apparently the plane who saw the object) estimated its speed (the object’s) at 180 M.P.H. A few seconds later he stated the object was going up and forward as fast as he was. He stated that he was going to 20,000 feet, and if no closer was going to abandon the chase. This was the last radio contact I heard.”

man13Inside a USAF Control Tower around 1947.

Colonel Hix’s statement regarding radio messages was admirably brief, noting only that: “I heard one of the pilots report that he saw the object straight ahead and estimated the speed of 180 M.P.H. The pilot stated that the object was very large and very bright.”

I have given the radio messages from the witness statements in detail here because there seems to be so much confusion about these messages. Many books and websites quote definitive messages from Mantell, but as you can see above no two witnesses agreed on precisely what was said. The best we can do is read these statements and note where they corroborate each other. After the event, other people not present in the tower at Godman claimed to have heard quite different messages via the Plan 62 Intercom system – the “My God! There are people inside” message was first claimed by a witness in the 1960s. Likewise, long after he had retired from the USAF, T Sgt. Blackwell gave an interview in which he claimed to have heard Mantell say: “We’re going to need hot guns!” Hot guns was USAF parlance for loaded weapons – none of the P-51 were carrying ammunition for their .50 Calibre machine guns on 7th December. However, Captain Duesler also gave an interview about the Mantell case after his retirement in which he claimed that all radio messages were as noted in the accident report. Unless these later claims about dramatic radio messages are corroborated, I don’t see that we can accept them as evidence.

Sometime after 15:00 the observers in the tower at Godman lost sight of the three Mustangs though they remained in radio contact. Sometime after 15:00 the other two aircraft in the flight lost sight of both Mantell and the strange object. Both were short of fuel by this time and flew on to their original destination at Standiford Army Airfield. Lt. Clements in NG 800 refuelled and immediately flew back over Godman and to the south. Although he climbed to over 30,000 feet, he saw nothing of Mantell or the strange object. By 16:45 the object was no longer visible to the personnel in Godman Tower and NG800 returned to Standiford and landed there.

man14Wreckage of Mantell’s aircraft. Note undamaged propeller blade.

It was unsurprising that Clements had not been able to find his flight leader when he flew back over Godman. At around 15:15 Glenn Mayes had stepped out of the back door of his house four miles south of the town of Franklin in Kentucky (around 90 miles from Godman) and heard an aircraft. He looked up and saw an aircraft circling at high altitude before starting a rapid descent. To his horror it appeared to partially disintegrate as it fell before the main part of the wreckage smashed into the ground only 300 yards from where he was standing. Although the aircraft was almost completely destroyed in the crash, there was no fire and a local ambulance which Mayes called recovered the body of Captain Mantell from the wreckage soon after. Captain Mantell was the first Kentucky Air National Guard pilot to die in the line of duty and in a bizarre coincidence, he was was born in the town of Franklin just a few miles from where he died.


  1. Godman AAF
  2. Crash site

However, the story of the strange object in the sky didn’t end with the death of Captain Mantel. A short time after the object was no longer visible to observers in the tower at Godman, a man from Madisonville, Kentucky called Flight Service in Dayton to report that he had watched the object through a telescope as it travelled southeast and that it was a balloon. 16:45 an astronomer from Nashville called in to say that he too had watched the object through a telescope and that it was a balloon. At 17:35 the Detachment Commander, Lieutenant Orner, returned to Control Tower at Godman and saw a bright light in approximately the position that the original object had been seen. He described this as a round object which did not resemble a star. Colonel Hix was once again called to the Tower and he also observed this object which was also watched and tracked using the Weather Station theodolite from the hangar roof until it disappeared below the horizon at 19:06.

At 19:20 observers in the Control Tower at Clinton County Army Air Field, Wilmington, Ohio reported something very similar to the object seen from Godman Tower. Initially this object appeared to be white, though it later appeared red to some observers. It was seen to descend at which point its shape could be more clearly seen – it was described as a “cone or up-side-down triangle” which was so brightly lit that it could be seen even when a cloud passed in front of it. Then at 19:55 the object was seen to head due South West at great speed and disappear over the horizon.

Meanwhile, at Lockbourne Army Air Base in Ohio personnel in the Control Tower had an equally odd sighting. At around 19:40 a light was seen in the sky to the southwest of the base, about 15° above the horizon. There was overcast and no stars were visible. The light was bigger and brighter than any star (one observer compared it in size and intensity to one of the runway lights). The strange object was also seen by an aircraft in the landing pattern at Lockbourne and the pilot of an Air Force C-45 which was over Columbus at 1953 hours at 5000 feet was asked by the Tower at Lockbourne whether he could see any strange light to the southwest of his position? The pilot responded that he had seen a bright light off his right wing, appearing like an oversized beacon. The pulsating light changed colour from red to amber several times while it was observed from the tower before abruptly descending and then disappearing at around 19:55.

The Report of Unusual Incident produced by the Project Sign team for events on the 7th January also includes the following notes, though no timings are given:

“Later we received a call from St. Louis Tower advising that a great ball of light was passing directly over the field – Scott Tower also verified this. We then received a call from Air Defense Command through Olmsted Flight Service Center advising us… that they had plotted the object as moving WSW at 250 miles per hour.”

man15Part of the USAF Accident Report

Later in 1948 the Air Force released an Accident Report on the Mantell incident. The cause of the crash and Mantell’s death were found to be anoxia due to lack of oxygen caused by Mantell climbing above the recommended height of 14,000 without oxygen equipment. This caused Mantell to lose consciousness and to lose control of his aircraft which then entered a dive and crashed. The report was less emphatic about what the object was that observers on the ground saw and Mantel tried to close in on. The report mentioned the possible presence of “a Navy cosmic ray balloon” in the area, but noted that it was not possible for a balloon to account for all sightings. The report also mentioned the possibility that all Mantell had seen was a reflection inside the canopy of his P-51but its final conclusion was that what he and everybody had seen was most likely the planet Venus. It stated that: “the first sightings were of some sort of balloon or aircraft and that when the reports came to Godman Field, a careful scrutiny of the sky revealed Venus, and it could be that Lieutenant Mantell did actually give chase to Venus.”


Let’s start with what we know not to be true. Many accounts of the Mantell incident include dramatic radio messages from Mantell saying something like “My God! There are people inside!” but no witnesses recalled anything of the sort. There has also been speculation that Mantell’s body wasn’t found in the crashed P-51 (it was), that his body exhibited strange injuries that could not be attributed to the crash (it didn’t) or that the aircraft itself showed the results of damage caused by something other than the rapid descent and crash (it didn’t). Most of these suggestions have come from those who support an extraterrestrial origin for the mystery object. My problem with this theory is that there is really no evidence to support it. The mystery object seen by most observers looked and moved like a balloon, not any form of extraterrestrial craft and the direct causes of Mantell’s crash and death seem to be entirely terrestrial and understood.

There seems little doubt that Mantell became fixated on climbing towards the object he was chasing to the point where his lack of oxygen caused him to lose consciousness. Although Mantell was a veteran pilot, he had relatively little experience of flying at altitudes which required the use of oxygen. Mantell’s service during World War Two had been with 440th Troop Carrier Group, 96th Troop Carrier Squadron, 9th Air Force where he flew only transport aircraft. When he joined “C” Flight, 165th Fighter Squadron of the Kentucky Air National Guard on 16th February 1947 he had no previous experience of the single engine fighter aircraft he would be required to fly and in particular no experience of high altitude flying which required the use of oxygen (no transport aircraft at that time were fitted with oxygen or cleared to fly above 14,000 feet). By January 1947 Mantell had logged over 2,300 hours as an Air Force pilot and 700 as a civilian pilot (he was an instructor at a local flying school which he also part owned) but he had spent less than seventy hours flying the P-51 Mustang.

If Mantell did become unconscious, his P-51 would have continued to climb for a time before entering a shallow left hand turn (due to the torque of a large piston engine, an aircraft will always tend to turn in the opposite direction to the direction of rotation of the propeller unless this is countered by the pilot). If left unattended, the aircraft would then have entered a steepening dive. Depending on the height at which the dive began and the speed attained, the aircraft might then have broken up in the air before crashing. This is precisely what appears to have happened to Mantell’s aircraft. The only slightly odd thing about the crash is the condition of the propeller of the P-51. In photographs, it’s clear that the Mustang has partially broken up in flight and hit the ground while falling vertically onto its left side. One of the blades of the four-bladed propeller is sticking up almost vertically and it’s clearly undamaged. This indicates that the propeller wasn’t turning when the aircraft hit the ground. That’s odd because if Mantell were unconscious, we would expect that the engine would still be running and the propeller still turning when the aircraft crashed. However, it is possible that the partial breakup of the fighter during its descent may have caused the propeller to stop, so it’s probably not wise to ascribe too much importance to this.

However, although it’s difficult to argue with the finding of the accident report in terms of the direct cause of the crash, it’s notable that the report does appear to have been put together rather carelessly. For example, the weather on the day of the accident is described as CAVU (Ceiling And Visibility Unlimited – in other words, a clear day with no clouds or haze) but several witness statements in the report mention the mystery object being temporarily obscured by cloud. The report also refers several times to “Lieutenant Mantell” whereas Mantell was actually a Captain. At one point it confuses Lt. Hendricks (who did not have sufficient fuel to join the other three aircraft in their search) with Lt. Hammond (who did), headings and heights are not always accurately given and there is the occasional typo (“discent” for descent for example). This looks very like something that has been put together hastily, but why would such a report be rushed out?

Part of the answer lies in a change in the public attitude of the Air Force towards flying saucers which happened towards the end of 1948 and the beginning of 1949. Behind closed doors, there was a great deal of concern at what were becoming known as Unidentified Flying Objects. In December 1948, the US Air Force and the US Navy produced a joint study of Unidentified Flying Objects which was issued as secret Air Intelligence Report No. 100-203-79, “Analysis of Flying Object Incidents in the U.S.” The report, which was de-classified in 1985, concluded that “It must be accepted that some type of flying objects have been observed, although their identification and origin are not discernible. In the interest of national defense it would be unwise to overlook the possibility that some of these objects may be of foreign origin.” In February 1949 the Air Force followed this up with Air Intelligence Requirements Memorandum Number 4 which contained very detailed requirements for the reporting “sightings of unconventional aircraft and unidentified flying objects, including the so-called “Flying Discs.””

Publically however, the US Air Force was being very careful to provide assurances that the whole flying saucer scare was nothing more than a series of errors and hoaxes. There is good evidence that in August 1948, the Project Sign Team produced a formal and Top Secret review of UFO incidents. One of the conclusions of the report was that UFOs could be of extraterrestrial origin. The report so enraged Air Force Chief of Staff General Hoyt S. Vandenburg that he ordered that all copies be destroyed. Project Sign was disbanded a short time later and replaced by Project Grudge which was soon reduced to only a single member of staff. The last report produced by Project Grudge before it was also disbanded in December 1949 stated that the 23% of UFO sightings that could not be explained as misperceptions of ordinary phenomena could be explained by psychology. In other words, all UFO sightings that weren’t mistakes were imaginary. Behind the scenes, we now know that at this time the Air Force were seriously considering whether it might be possible to use missiles to shoot down one of these imaginary craft, but in public, UFOs did not exist.

Hoyt S. Vandenberg

General Hoyt S. Vandenburg

And I think we have to see the Accident Report on the Mantell incident in this context. The Mantell case (just like the Roswell incident four months before) had attracted a huge amount of publicity. The Air Force wanted a report which would attribute the accident and the sightings which accompanied it to a very prosaic cause. It certainly didn’t want any suggestion that the object Mantell had been chasing was unidentified. Thus the conclusion that Mantell and everybody else who reported sighting strange objects in the sky had actually seen Venus, or possibly a Navy balloon, or even just a reflection from a cockpit canopy.

The Accident Report was greeted with widespread scepticism even inside the US military. We know from declassified Air Force documents that the object sighted during the Mantell incident continued to be considered “unknown” within the Air Force. And really, the theory that everyone involved had actually misperceived Venus doesn’t stand up to rational examination. Venus was certainly in the sky at the times of the sightings, and in approximately the location of the object reported by observers at Godman. But Venus in daylight, even at its brightest, is only a tiny point of light. The idea that a number of professional airmen and ground staff could mistake Venus for a large object in the sky is not credible. If we add this to the fact that the descriptions of many observers are similar and clearly describe something other than a point of light, Venus cannot be the answer.

What then about the theory that Mantell and observers on the ground actually saw a Skyhook balloon released by the US Navy? In the years that followed the release of the original Accident Report, this came to be widely believed and has become the most often quoted solution to the Mantell mystery. But is this actually a tenable theory?

By 1950, as sightings of what were now called UFOs continued unabated, Project Grudge was resurrected and then re-named Project Blue Book. The ostensible purpose of Blue Book was just the same as it had been for Sign and Grudge: to objectively evaluate sightings of UFOs. But many people believed that Blue Book had another, hidden agenda: to quash public fears about UFOs by “proving” that all sightings had a rational and conventional explanation. This feeling was strengthened when Edward J. Ruppelt was appointed the new Director of Project Grudge and then of Blue Book when the project was re-named in March 1952. Ruppelt certainly brought much needed energy and organisation to these projects, but he was also very sceptical about UFOs being anything other than misinterpretations of natural phemomena which also fitted nicely with the view the Air Force wanted to promulgate. Ruppelt left the Air Force in 1954 and in 1956 published a book, The Report on Unidentified Flying Objects, about his experiences in Projects Grudge and Blue Book. The overall conclusion of the book was that the idea that UFOs had an extraterrestrial origin was nothing more than a “space-age myth.”

However, Ruppelt’s book is interesting because it included a re-appraisal of the Mantell case. Ruppelt admitted that the Venus theory was extremely unlikely and instead he offered the solution that what Mantell had been chasing was a secret US Navy Skyhook balloon. The quotes below all come from Ruppelt’s book:

“The possibility of a balloon’s causing the sighting had been mentioned but hadn’t been followed up…” “…a quick check had been made on weather balloons and none were in the area. The big skyhook balloon project was highly classified at that time, and since they were all convinced that the object was of interplanetary origin they didn’t want to bother to buck the red tape of security to get data on skyhook flights.

The group who supervise the contracts for all the skyhook research flights for the Air Force are located at Wright Field, so I called them. They had no records on flights in 1948 but they did think that the big balloons were being launched from Clinton County AFB in southern Ohio at that time. 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. By assuming the shape of one piece, a balloon launched from southwestern Ohio, the whole picture neatly falls together. It shows a huge balloon that Captain Thomas Mantell died trying to reach. He didn’t know that he was chasing a balloon because he had never heard of a huge, 100-foot-diameter skyhook balloon, let alone seen one. Leave out the one piece of the jigsaw puzzle and the picture is a UFO, “metallic and tremendous in size.”

It could have been a balloon. This is the answer I phoned back to the Pentagon.”

Edward J. Ruppelt, The Report on Unidentified Flying Objects, 1956

And this, in essence, is the balloon theory which has come to be generally accepted as the solution to the Mantell mystery. However, there are a number of issues with Ruppelt’s story. He tells us that Mantell and observers on the ground could not have been aware of Skyhook balloons because the project was “highly classified”. This simply isn’t true. Skyhook certainly was a real US Navy project to operate large balloons but the project was never classified. The large Skyhook balloons, which were made by the Aeronautical Division of General Mills, Inc. and constructed out of translucent polyethylene, were mentioned in the New York Times in 1946 and 1947 and even provided the front cover story in Popular Science magazine in May 1948. It is true that the US navy claimed that the balloons were intended for “high altitude cosmic ray research” and that some of the payloads they carried were classified and were probably used to gather intelligence data, but Skyhook itself wasn’t a secret project, which Ruppelt must have known. Ruppelt also claims that the observers at Godman failed to identify the strange object as a balloon because “they were all convinced that the object was of interplanetary origin”. There is no evidence at all to support this statement. The observers at Godman could not identify what they were looking at, but there is no suggestion that they believed they were watching an alien craft.

man17The front cover of Popular Science magazine, May 1948 featured an artist’s impression of a Skyhook balloon. The article inside included photographs and details of the Skyhook project. Yet in 1956 Ruppelt claimed that this project was “highly classified” in 1948.

To account for the various sightings, Ruppelt explains that the Skyhook balloon must first have drifted west from Clinton AFB, gaining altitude and being seen from towns to the west of Godman. Then, it must have reached an altitude of around 60,000 feet and entered the jetstream which took it to the south. While observers at Godman watched, the balloon continued to drift south before disappearing from view. Ruppelt is a little generous with both his estimate of the size of the Skyhook balloon (he claims 100 feet diameter when it was actually closer to 70 feet) and the distance at which it can be seen with the naked eye (he claims 50-60 miles, when 50 miles is probably the absolute maximum). Simple trigonometry tells us that for an object the size of a skyhook balloon to be visible at 60,000 feet, it must have been flying above a point on the earth no more than 48 miles from the tower at Godman and probably less.

Now consider that the P-51D was a very fast aircraft – it was one of the fastest piston engine fighters of World War Two with a maximum speed of a little under 500mph at 25,000 feet and a cruising speed of 325mph at 10,000 feet. The P-51D could climb to 20,000 feet in under seven and a half minutes and even at maximum climb its speed was over 180mph. Even if continually climbing, Mantell, would have been directly under an object 48 miles from Godman tower in a maximum of 15 minutes. And if he had been continually climbing, Mantell would have reached 25,000 feet (the altitude at which he would almost certainly have become unconscious from lack of oxygen) around ten minutes after leaving the vicinity of Godman which implies that for at least part of the time he was flying level and therefore faster.

man18Skyhook balloon being prepared for launch from the flight deck of USS Palau, 1948. Note the comparative sizes of the balloon and the aircraft parked on the deck.

T Sgt Blackwell’s statement tells us that Mantell’s flight were first contacted soon after 14:30 and that by 14:45 Mantell was flying towards the object which he had in sight and was climbing towards. Thirty minutes later and at 15,000 ft, Mantell reported, “I’m still climbing, the object is above and ahead of me moving at about my speed or faster, I’m trying to close in for a better look.” One of the few things that all witnesses in Godman Tower agreed upon was that in his last radio message, Mantell reported that the object was still ahead of him. At that point he must have been around ninety miles southwest of Godman, which also correlates to the crash site of the Mustang a few minutes later at Franklin, just over ninety-five miles southwest from Godman. It’s just not possible that a Skyhook balloon which was 48 miles from Godman when Mantell set off (and we know a Skyhook balloon couldn’t have been any further away from Godman or it wouldn’t have still been visible to observers there) could still be ahead of him after thirty minutes of flying towards it. If the mystery object had been a Skyhook, Mantell must have passed underneath it long before his final radio message. But we know that he didn’t because he reported that it was still ahead of him in his final radio message.


  1. Mantell’s presumed route from Godman Field to the crash site at Franklyn.
  2. The maximum range at which a Skyhook balloon would have been visible to observers at Godman.

What does all this tell us? It almost certainly means that the object seen from Godman Tower and which Mantell flew towards was much larger (and therefore visible from a greater distance) than a Skyhook balloon. This also ties in with a statement given by Lt Col E. Garrison Wood, who was also present in Godman Tower on the 7th, that  “…as compared to the diminishing size of the P-51’s flying toward it, it would seem that it was at least several hundred feet in diameter.” Although it initially sounds rational, it’s beginning to seem that the Skyhook balloon theory was just another Air Force attempt to explain away the Mantell incident in conventional terms. Although it is easier to accept than the Venus theory, simple mathematics seems to rule out the Skyhook balloon out as a genuine option.


When I started writing this article, I was fairly confident that a Skyhook balloon was the most probable cause of the various sightings on 7th January 1948 (I have never been able to take the Venus explanation seriously). However, as noted above, there are serious reasons to doubt that a Skyhook balloon could have been the object seen, mainly because such a balloon is simply too small to be seen from Godman at a range where Mantell would not have reached it well before the time of his crash. That’s a little surprising because so many of the eyewitness descriptions of the object seen on 7th December do sound like a balloon with something slung underneath – “an ice cream cone”, “a parachute with bright sun shining on the top of the silk”, “a very large, white, umbrella shaped object” and “a cone or up-side-down triangle.” Two witnesses who viewed the object through telescopes from the ground specifically said that it was a balloon. But witnesses estimated the size of the object they were looking at as much larger than a Skyhook – “250-300 feet in diameter”, sighting from the ground in Elizabethtown and “at least several hundred feet in diameter”, sighting from Godman Tower. A Skyhook balloon was around 50 feet in diameter when launched and, as it rose to thinner air at higher altitude, the hydrogen or helium with which it was filled would expand the plastic envelope. In addition and contrary to what Ruppelt tells us, we know that the US Navy Skyhook project was not classified so, if there really had been a Skyhook balloon in the area, there is no reason that this information wouldn’t have been available to accident investigators.

man19US Navy Skyhook balloon

Finally, there is Ruppelt’s suggestion that the Skyhook balloon he claims caused the sightings may have been launched from Clinton County AAF in Ohio in the early morning of 7th January. And yet, one of the sightings reported in the evening of 7th January of a “cone or up-side-down triangle” which was so brightly lit that it could be seen even when a cloud passed in front of it came from the Tower at this same base. This sounds very like the same object seen from Godman but presumably observers at this base would have been familiar with Skyhook balloons?

If for the reasons noted above we accept that a Skyhook balloon cannot have been the object sighted, just what was it? Could it have been an extraterrestrial craft? Frankly, there is nothing to support this notion. To most observers the object looked like a balloon and it seemed to drift or move very slowly, just like a balloon. For these reasons and in the absence of any credible evidence to the contrary, I’m going to apply Occam’s Razor here and assume that it most probably was a balloon. But it must have been considerably larger than a Skyhook, so what could it have been? To consider this, we need to think about why the US Navy (and the Air Force) were experimenting with balloon flights at this time.

The stated purpose of the Skyhook programme was scientific research into cosmic rays and high altitude weather patterns. While such experiments certainly were done using Skyhook balloons, there was another pressing reason for the US to develop high-altitude balloons. By 1947, the Cold War was in full swing with the US pledging assistance to countries faced with “Soviet expansionism”. The Soviet Union was seen as the principal enemy of the Western alliance but what was lacking was information about what was happening deep within Soviet territory. Conventional aircraft could not fly high enough to safely penetrate Soviet airspace (the first U2 high-altitude reconnaissance aircraft would not come into service until 1955) and there were no reconnaissance satellites in the 1940s or 1950s. However, it seemed possible that a balloon able to drift at high altitude, above the range of Soviet air defences, could be used to provide essential reconnaissance information.

The US Navy and the US Air Force designed and built a whole range of balloons under a number of Projects during the late 1940s and early 1950s. In many cases an unclassified project was used to hide a classified project. For example, the US Air Force launched Project Moby Dick in 1952 with the stated purpose of measuring global high-altitude wind patterns. However, buried within Moby Dick was another, classified project named Gopher. Project Gopher involved balloons carrying large camera gondolas which could remain aloft at high altitude for at least sixteen days. The intention was to allow Project Gopher balloons to drift over the Soviet Union at high altitude and then to recover the camera gondola and study the film. The balloons used for Gopher were so large that it was clear that it wouldn’t be possible to hide launches from observers on the ground (and the CAA wouldn’t allow night launches because of the danger of a collision with a civilian aircraft), so launches of secret Gopher balloons were explained away as launches of unclassified Moby Dick balloons.

man20Preparing to launch a Moby Dick balloon at Hollman AFB, 1956

Is it possible that there was another, classified balloon project hidden within the US Navy Skyhook project? Perhaps something that operated larger balloons? A tantalizing clue appeared in the February 1951 edition of Look magazine in an article by Dr Urner Liddel, Head of the Office of Naval Research titled “A Nuclear Physicist Exposes Flying Saucers”. The article was yet another officially sponsored debunking attempt to explain all UFO sightings as balloons. Dr Liddel described the Skyhook project and then mentioned that “General Mills and the Office of Naval Research are working on a new balloon with four times the capacity of the Skyhook, which can rise to heights of 120,000 feet.” That would certainly be a giant balloon and as far as I am aware, this is the only contemporary mention of such a thing. Officially at least, the US Navy was never involved with a balloon of this size. Was Dr Liddel perhaps inadvertently referring to the existence of much larger balloons operated by the US Navy?

Then, in the May/June 2004 edition of the Skeptical Enquirer there appeared an article written by B. D. Gildenberg titled The Cold War’s Classified Skyhook Program: A Participant’s Revelations. Bildenberg was involved in the US Army Project Mogul (the equivalent of the US Navy Skyhook Project) and was very familiar with these balloons. The article explains that many UFO sightings from the late 1940s/early 1950s were most likely due to these balloons. The interesting part is where he notes that:

“Skyhook balloons were huge. The average size of those discussed in this article was double the six million cubic feet of the Hindenberg. Their diameters were about 300 feet with a flaccid length of 430 feet.”

The problem is, a twelve million cubic foot capacity balloon with a diameter of 300 feet is much, much bigger than any previously published figures for Skyhook. Even the largest known balloons created for the later Moby Dick, Gopher, Genetrix and Manhigh projects had a diameter of less than 150 feet. Either Mr Bildenberg is completely wrong in his figures or he’s talking about a balloon which did not officially exist.

man21Launch of a USAF Project Manhigh balloon in 1957. This project used a large polyethelene balloon to lift a man in a small capsule to the stratosphere.

I’m inclined to believe that the second option is probably correct. We know that the US Navy and Air Force were considering some fairly dramatic balloon projects in the late 1940s, including the possibility of suspending a nuclear warhead beneath a balloon. Lifting a payload as heavy as that to an altitude where it could safely overfly the Soviet Union would have required something much bigger than a Skyhook balloon. Launching a very large balloon for test flights would inevitably involve it being seen from the ground. What better way to conceal the existence of such a balloon than by hiding it in plain sight by claiming it was part of the Skyhook Project? After all, it would be very difficult for an observer on the ground to be certain whether they were looking at a 70 foot Skyhook balloon at a range of 50 miles or a much bigger balloon at 100 miles.

A very large (perhaps 200 – 300 foot diameter) balloon could satisfactorily account for all the sightings of 7th January. The official Accident Report into Mantell’s death tied itself in knots trying to account for all the sightings because many were physically too far apart to be accounted for by a single 70 foot diameter Skyhook balloon. To resolve this, the report postulated two unknown objects in the sky (possibly balloons) in addition to the misidentification of Venus. However, if the balloon involved was much bigger, this would account for all the ground sightings and for the fact that Mantell reported it as still being ahead of him after thirty minutes of flying. I believe that the object involved in the Mantell incident was indeed a balloon, but it must have been a balloon much bigger than anything known to exist at the time.

I suppose that for many people this may not be a very satisfying proposed solution to the Mantell Mystery. After all, I can’t prove that a very large balloon was the object sighted on the 7th January. However, if we note the hints of the existence of a much bigger balloon than Skyhook, the fact that both the USAF and the US Navy were considering a number of clandestine uses for balloons and that we know that the US Navy later used unclassified balloon projects to hide classified projects, I think we can at least say that it is possible that a classified project existed in 1948 which involved very large balloons. If this is possible, then it’s also possible that such a balloon was involved in the Mantell mystery.

Case closed? Not quite, but I do think this offers the most plausible solution based on the available evidence.


The Report on Unidentified Flying Objects, 1956, by Edward J. Ruppelt

Rupplet’s book on his time in Projects Grudge and Blue Book is now out of copyright and may be freely downloaded from Project Gutenberg.

The Thomas Mantell UFO Encounter, 2015 by George Dudding

A very short (23 page) book which gives details of the Mantell case including claims of new radio messages which confirm that the mystery object was some sort of alien craft.

The Mantell Incident – Anatomy of an investigation

Very detailed examination of the Mantell incident including links to scans of many original USAF documents from NICAP (National Investigations Committee on Ariel Phenomena).

The Cold War’s Classified Skyhook Program: A Participant’s Revelations

Article on the CSI (Committee for Skeptical Enquiry) website by B.D. Bildenberg which claims 300 foot diameter for Skyhook balloons.


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