I created a table of content below; which was not part of the original scientific publication. The 56 pages publication is some 250Kb and I broke it in several files for acceptable web access speed.
Please go to the Science section of this website for more scientific papers by James E. McDonald and other scientists, plus comments and information regarding scientists' work and position about the UFO phenomenon.
The skeptic who asks this question, and many do, is asking a very reasonable question. With so much radar equipment deployed all over the world, and especially within the United States, it seems sensible to expect that, if there are any airborne devices maneuvering in our airspace, they ought to show up on radars once in a while. They do indeed, and have been doing so for all of the two decades that radar has been in widespread use. Here, as with so many other general misconceptions about the true state of the UFO problem, we encounter disturbingly large amounts of misinformation. As with other categories of UFO misinformation, the only adequate corrective is detailed discussion of large numbers of individual cases. Only space limitations preclude discussion of dozens of striking radar-tracking incidents involving UFOs, both here and abroad; they do exist.
A very early radar-UFO case, still held as an official Unidentified, involved an attempted interception of the unknown object by an F-61 flying near Fukuoka, Japan, at about 11:00 p.m. local time on 10/15/48. The official file on this incident is lengthy (Ref. 42); only the highlights can be recounted here. The F-61 (with pilot and radar operator) made six attempts to close with the unknown, from which a radar return was repeatedly obtained with the airborne radar. Each time the radarman would get a contact and the F-61 pilot tried to close, the unknown would accelerate and pass out of range. Although the radar return seemed comparable to that of a conventional aircraft,
"the radar observer estimated that on three of the sightings, the object traveled seven miles in approximately twenty seconds, giving a speed of approximately 1200 mph."
In another passage, the official case-file remarks that
"when the F-61 approached within 12,000 feet, the target executed a 180 degree turn and dived under the F-61."
adding that
"the F-61 attempted to dive with the target but was unable to keep pace."
The report mentions that the unknown
"could go almost straight up or down out of radar elevation limits,"
and asserts further that
"this aircraft seemed to be cognizant of the whereabouts of the F-61 at all times..."
The F-61 airmen, 1st Lt. Oliver Hemphill (pilot) and 2d Lt. Barton Halter (radarman) are described in the report as being
"of excellent character and intelligence and are trained observers."
Hemphill, drawing on his combat experience in the European theater, said that
"the only aircraft I can compare our targets to is the German ME-163."
The airmen felt obliged to consider the possibility that their six attempted intercepts involved more than one unknown. Hemphill mentions that, in the first attempted intercept,
"the target put on a tremendous burst of speed and dived so fast that we were unable to stay with it."
After this head-on intercept, Hemphill did a chandelle back to his original 6000-ft altitude and tried a stern interception,
"but the aircraft immediately outdistanced us. The third target was spotted visually by myself,"
Hemphill's signed statement in the case-file continues.
"I had an excellent silhouette of the target thrown against a very reflective undercast by a full moon. I realized at this time that it did not look like any type of aircraft I was familiar with, so I immediately contacted my Ground Control Station..."
which informed him there were no other known aircraft in the area. Hemphill's statement adds further that,
"The fourth target passed directly over my ship from astern to bow at a speed of roughly twice that of my aircraft, 200 mph. I caught just a fleeing glimpse of the aircraft; just enough to know that he had passed on. The fifth and sixth targets were attempted radar interceptions, but their high rate of speed put them immediately out of our range."
(Note the non-committal terminology that treats each intercept target as if it might have been a separate object.) A sketch of what the object looked like when seen in silhouette - against the moonlit cloud deck is contained in the file. It was estimated to be about the size of a fighter aircraft, but had neither discernible wings nor tail structures. It was somewhat bullet-shaped, tapered towards the rear, but with a square-cut aft end. It seemed to have "a dark or dull finish".
Ground radar stations never detected the unknown that was seen visually and contacted by airborne radar. The report indicates that this may have been due to effects of "ground clutter", though the F-61 was seen intermittently on the ground units. The airmen stated that no exhaust flames or trail were seen from this object with its "stubby, clean lines". The total duration of the six attempted intercepts is given as 10 minutes. We deal here with one of many cases wherein radar detection of an unconventional object was supported by visual observation. That this is carried as Unidentified cannot surprise one; what is surprising is that so many other comparable instances are on record, yet have been ignored as indicators of some scientifically intriguing problem demanding intensive study.
The first UFO case to command general press attention in the Australian area seems to have been a combined radar-visual sighting wherein the pilot of a Hawker Seafury from Nowra Naval Air Station visually observed two unknown objects near him as he flew from Canberra to Nowra (Ref. 43). Press descriptions revealed only that the pilot said "the two strange aircraft resembling flying saucers" were capable of speeds much beyond his Seafury fighter. He saw them flying nearby and contacted Nowra radar to ask if they had him on their scope; they informed him that they had three separate returns, at which juncture he described the unidentified objects. Under instructions from the Nowra radar operator, he executed certain maneuvers to identify himself on the scope. This confirmed the scope-identity of his aircraft vs. the unknowns. As he executed the test maneuvers, the two unknowns moved away and disappeared. No explanation of this incident was offered by Naval authorities after it was widely reported in Australian and New Zealand papers about three months after it occurred.
It is mildly amusing that the press accounts indicated that
"the pilot, fearing that he might be ragged in the wardroom on his return if he abruptly reported flying saucers, called Nowra by radio and asked whether the radar screen showed his aircraft."
Only after getting word of three, not one, radar blips in his locality did he radio the information on the unknowns, whose configuration was not publicly released. This is in good accord with my own direct experience in interviewing Australian UFO witnesses in 1967; they are no more willing than Americans to be ridiculed for seeing something that is not supposed to exist.
In November 1953, the South African Air Force released a brief announcement concerning radar-tracking of six successive passes of one or more unknown high-speed objects over the Cape. On January 1, 1967, in a transoceanic shortwave broadcast from South Africa, the authenticity of this report was confirmed, though no additional data beyond what had been cited earlier were presented. In the six passes, the target's altitude varied between 5,000 and 15,000 ft, and its closest approach varied between 7 and 10 miles. Speeds were estimated at over 1200 mph, well beyond those of any aircraft operating in that area at that time.
This report, on which the available information is slim, is cited to indicate that not only visual sightings but also radar sightings of seemingly unconventional objects appear to comprise a global phenomenon. By and large, foreign radar sightings are not readily accessible, and not easily cross-checked. Zigel (Ref. 38) briefly mentions a Russian incident in which both airborne and ground-based radar tracked an unidentified in the vicinity of Odessa, on April 4, 1966, the ground-based height-finding radar indicating altitudes of well over 100,000 ft. Such reports, without accessory information, are not readily evaluated, of course.
By far the most famous single radar-visual sighting on record is the one which occurred late in the evening of July 19, and early on July 20, 1952, in the vicinity of Washington, D.C. (Refs. 2, 4, 5, 10, 24, 25). A curiously similar incident occurred just one week later. The official explanation centered around atmospheric effects on radar and light propagation. Just before midnight on July 19/20, CAA radar showed a number of unidentified targets which varied in speed (up to about 800 mph) in a manner inconsistent with conventional aircraft. A number of experienced CAA radarmen observed these returns, and, at one juncture, compatible returns were being received not only at the ARTC radar but also on the ARS radar in a separate location at Washington National Airport, and on still a third radar at Andrews AFB. Concurrently, both ground and airborne observers saw unidentifiable lights in locations matching those of the blips on the ground radar.
I have interviewed five of the CAA personnel involved in this case and four of the commercial airline pilots involved, I have checked the radiosonde data against well-known radar propagation relations, and I have studied the CAA report subsequently published on this event. Only an extremely lengthy discussion would suffice to present the serious objections to the official explanation that this complex sighting was a result of anomalous radar propagation and refractive anomalies of the mirage type. The refractive index gradient, even after making allowance for instrument lag, was far too low for "ducting" or "trapping" to occur; and, still more significant, the angular elevations of the visually observed unknowns lay far too high for radar-ducting under even the most extreme conditions that have ever been observed in the atmosphere. Some of the pilots, directed by ground radar to look for any airborne objects, saw them at altitudes well above their own flight altitudes, and these objects were maneuvering in wholly unconventional manner. One crew saw one of the unknown luminous objects shoot straight up, and simultaneously the object' s return disappeared from the ARTC scope being watched by the CAA radar operators. The official suggestion that the same weak (1.7"C) low-level "inversion" that was blamed for the radar ducting could produce miraging effects was quantitatively absurd, even if one overlooks the airline-pilot sightings and deals only with the reported ground-visual sightings. From the CAA radar operators I interviewed, as well as from the pilots I talked to about this case, I got the impression that the propagation-anomaly hypothesis struck them as quite out of the question, then and now. In fact, CAA senior controller Harry G. Barnes, who told me that the scope returns from the unknowns
"were not diffuse, shapeless blobs such as one gets from ground returns under anomalous propagation."
but were strong, bright pips, said that
"anomalous propagation never entered our heads as an explanation."
Howard S. Conklin, who, like Barnes, is still with FAA, was in the control tower that night, operating an entirely independent radar (short-range ARS radar) . He told me that what impressed him about the sighting that night was that they were in radio Communication with airlines crewmen who saw unidentified lights in the air in the same area as unknowns were showing up on his tower radar, while simultaneously he and Joseph Zacko were viewing the lights themselves from the tower at the D.C. Airport. James M. Ritchey, who was at the ARTC radar with Barnes and others, confirmed the important point that simultaneous radar fixes and pilot-sightings occurred several times that night. He shared Barnes' view that the experienced radar controllers on duty that night were not being fooled by ground returns in that July 19 incident. Among the airlines crewmen with whom I spoke about this event was S.C. Pierman, then flying for Capitol Airlines. He was one of the pilots directed by ground radar to search in a specific area for airborne objects. He observed high speed lights moving above his aircraft in directions and locations matching what the CAA radar personnel were describing to him by radio, as seen on their radars. Other airline personnel have given me similar corroborating statements. I am afraid it is difficult to accept the official explanations for the famous Washington National Airport sightings.
Many of the radar cases for which sighting details are accessible date back to 1953 and preceding years. After 1953, official policies were changed, and it is not easy to secure good information on subsequent cases in most instances. A radar case in which both ground-radar and airborne radar contact were involved occurred at about 9:40 p.m. CST on 7/29/52 (Refs. 4, 5, 7, 10, 25). From the official case summary (Ref. 7) one finds that the unknown was first detected by GCI radar at an Aircraft Control and Warning station in Michigan, and one of three F-94s doing intercept exercises nearby was vectored over towards it. It was initially coming in out of the north (Ref. 5, 25), at a speed put at over 600 mph. As the F-94 was observed on the GCI scope to approach the unknown, the latter suddenly executed a 180 degree turn, and headed back north. The F-94 was by then up to 21,000 ft, and the pilot spotted a brilliant multicolored light just as his radarman got a contact. The F-94 followed on a pursuit course for 20 minutes (Ref. 7) but could never close with the unknown as it continued on its northbound course. At the time of first radar lock on, the F-94 was 20 miles west of Pt. Huron, Mich. The GCI scope revealed the unknown to be changing speed erratically, and at one stage it was evidently moving at a speed of over 1400 mph, according to Menzel (Ref. 25), who evidently drew his information from the official files. Ruppelt (Ref. 5) states that when the jet began to run low on fuel and turned back to its base, GCI observed the unknown blip slow down, and shortly after it was lost from the GCI scope.
This case is still carried as an official Unknown. The case summary (Ref. 7) speculates briefly on whether it could have been
"a series of coincident weather phenomena affecting the radar equipment and sightings of Capella, but this is stretching probabilities too far."
Menzel, however, asserts that the pilot did see Capella, and that the air borne and ground radar returns
"Were merely phantom returns caused by weather conditions."
No suggestion is offered as to how any given meteorological condition could jointly throw off radar at the ground and radar at 21,000 feet, no suggestion is offered to account for 180 degree course-reversal exhibited by the blip on the GCI scope just as the F-94 came near the unknown, no suggestion of how propagation anomalies could yield the impression of a blip moving systematically northward for 20 minutes (a distance of almost 100 miles, judging from reported F-94 speeds), with the F-94 return following along behind it. With such ad hoc explanations, one could explain away almost any kind of sighting, regardless of its content. I have examined the radiosonde sounding for stations near the site and time of this incident, and see nothing in them that would support Menzel's interpretations. I have queried experienced military pilots and radar personnel, and none have heard of anything like "ground returns" from atmospheric conditions with aircraft radar operated in the middle troposphere. If Menzel is not considering ground-returns, in the several cases of this type which he explains away with a few remarks about "phantom radar returns", then it is not clear what else he might be thinking of. One does have to have some solid target to get a radar return resembling that of an aircraft. Refractive anomalies of the "angel" type have very low radar cross-section and would not mislead experienced operators into confusing them with aircraft echoes.
6. Many other cases might be cited where UFOs have appeared on radar under conditions where no acceptable conventional explanation exists. Ref. 7 has a number of them. Hall (Ref. 10) has about 60 instances in which both radar and visual sightings were involved. A December 19, 1964 case at Patuxent River NAS is one that I have checked on. It involved three successive passes of an unknown moving at speeds estimated at about 7000 mph. It is an interesting case, one that came to light for somewhat curious reasons. A low overcast precluded any visual sightings from control tower personnel, so this is not a radar-visual case. I found no conventional explanation to account for it.
It has to be stressed that there are many ways in which false returns can be seen on radarscopes, resulting not only from ducting of ground returns but also from interference from other nearby radars, from internal electronic signals within the radar set, from angels and insects (weak returns), etc. Hence each case has to be examined independently. After studying a number of official evaluations of radar UFO cases, I get the impression that there would probably be more radar Unknowns if there were less tendency to quickly explain them away by qualitative arguments that overlook pertinent quantitative matters. Even at that, there are too many conceded unknowns in official files to be ignored. A famous case in UFO annals involved a B-29 over the Gulf of Mexico, where several unknowns were tracked on the airborne scopes and were seen simultaneously by crew men, moving under the aircraft as they passed by (Refs. 4, 10, 25). This one is still carried as Unidentified in official files. Still another famous combined radar-visual case, which Hynek has termed "one of the most puzzling cases I have studied," occurred between Rapid City and Bismarck on August 5, 1953. It involved both ground and airborne radar and ground and airborne visual sightings, but is far too long and complex to recapitulate here.
Perhaps the above suffices to indicate that UFOs are at times seen on radar and have been seen for many years. The question of why we don't hear a great deal about such sightings, especially with newer and more elaborate surveillance radars, is a reasonable question. Some of the answers to that one are posed by the statement of Dr. Robert M. L. Baker, Jr., in these proceedings. Other parts of the answer must be omitted here.
