Article/Document:
Physical Evidence Related to UFO Reports (Sturrock Panel): Radar Evidence
Peter Sturrock / Sturrock Panel Report / Physical Evidence Related to UFO Reports
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Summary: Velasco presented information on radar cases drawn in part from the files of GEPAN/SEPRA (see Appendix 1). He pointed out that one catalog (the "Weinstein catalog" now under development at GEPAN/SEPRA), with 489 cases in all, contains 101 (21%) radar/visual cases (cases that involve both radar detection and visual observation), and the files of the US Air Force Blue Book project contain 363 cases of which 76 (21%) are radar/visual cases.
Velasco presented information on radar cases drawn in part from the files of GEPAN/SEPRA (see Appendix 1). He pointed out that one catalog (the "Weinstein catalog" now under development at GEPAN/SEPRA), with 489 cases in all, contains 101 (21%) radar/visual cases (cases that involve both radar detection and visual observation), and the files of the US Air Force Blue Book project contain 363 cases of which 76 (21%) are radar/visual cases. Since 1945, reports of aeronautical cases have been collected by order of the French Air Force Chief of Staff. From 1977 on, information from civil and military observations made in French air-space have been sent to GEPAN/SEPRA (see Appendix 1). It should be noted that civil radar information usually refers only to objects containing a transponder, whereas military radar equipment can detect any object greater than two square meters in radar equivalent surface area. From 1982 on, twelve French aeronautical cases were reported to GEPAN/SEPRA. Of these, only three or four cases may be considered to be radar-visual cases of the UFO type.
One of these cases is particularly interesting. This case occurred on January 28, 1994, about 70 kilometers southeast of Paris, at a height of 11,700 meters, under excellent meteorological conditions. An object was first noticed by a steward who happened to be in the cockpit, and his observation was then confirmed by the copilot. The captain then saw the object. It was above the thick layer of altocumulus clouds at 10,500 meters. The captain described the object as resembling a gigantic disk (diameter about 1000 meters, thickness about 100 meters) with slightly fuzzy edges. The witnesses suddenly lost sight of the object when the edges appeared to go out of focus and the object disappeared.
Corresponding radar information was obtained from the military air traffic control (ATC). The object was positively detected by radar for a period of 50 seconds. The apparent speed of the object was measured first as 110 knots, then as 84 knots, and subsequently as zero. The altitude of the object was not recorded by radar. The radar was also tracking a nearby commercial aircraft and appeared to be in good working order. There appears to be good correspondence between the radar measurements and the visual observations.
Von Ludwiger also presented information concerning radar evidence, drawing in part on the results of studies that he had carried out in association with other members of the Mutual UFO Network (MUFON) Central European Society (MUFON-CES). For a certain period of time, they were able to obtain records from both civil and military ATC radar systems. The Swiss Military ATC was particularly cooperative, and provided several hundred hours of radar data over the time period 1993 to 1996. Radar data were also obtained from Belgian sources through the good offices of Professor A. Messens (SOBEPS, 1991). Military ATC radar systems provide three-dimensional information, whereas civilian ATC radar systems provide only two-dimensional information. Furthermore, the functioning of civilian ATC radar systems normally depend upon the cooperation of a transponder in the object being tracked. For this reason, civilian ATC radar records are usually not helpful for the study of unidentified objects. Moreover, there is the general problem that ATC systems are designed to register only targets for which the flight characteristics fall within certain parameter ranges. For instance, any object that moves faster than Mach 4, or does not follow a smooth trajectory, will be rejected by the system whether civil or military, and so will not be tracked. A further limitation, relevant to the study in hand, is that conditions for a good radar record and conditions for a good visual sighting are quite different. An object can best be seen if it is at low altitude, but radar systems normally do not detect objects at low altitude.
In the United States, the Federal Aviation Administration (FAA) radar routinely records on tape all targets, not just aircraft with transponders. Of course, radar systems record only objects that are sufficiently close and have high enough altitude. Although it is unlikely that private investigators will be able to obtain regular access to these records, such access has been granted on occasion. Such data can be very helpful in providing physical evidence for cases that have reliable witness testimony, in which case the records can be compared to witness testimony to determine whether an object seen visually was also recorded on radar, and — if so — to obtain accurate velocity estimates.
According to von Ludwiger, there are many events, involving both visual observations and radar responses, in Swiss airspace but the radar records are not publicly available. However, one case for which radar records were released occurred on June 5, 1996 at about 2:30 p.m. Six employees, including radar operators, of the military ATC at Dubendorf, Switzerland observed from their building in Klothen a large silvery disk apparently at a distance of 1700 meters. It appeared to be rotating and wobbling at an altitude of 1300 to 2000 meters. There was a corresponding recording of a target by three radar devices.
Von Ludwiger also mentioned a number of other cases of radar targets, some of which followed curious trajectories unlike those of conventional aircraft. Recognition of these anomalous trajectories typically came some time after the events when the radar data were analyzed. Von Ludwiger considers this to be one reason that (except for two cases) it was normally not possible to find corresponding visual observations. Von Ludwiger considers that for many of these cases the most likely explanation involves anomalous atmospheric refraction of the radar signals, but that some cases for which the radar records showed very long connected trajectories may have been produced by real objects. (See Appendix 4.)
The panel concludes from these presentations that the analysis of radar records is a very specialized activity that requires the services of radar experts. (See, in this connection, Appendix 4.) The panel also notes that information from military radar can be obtained only with the cooperation of military authorities, and that most military authorities do not offer this cooperation. Although intriguing cases have been presented by both Velasco and von Ludwiger, further study of this phenomenon by means of radar-visual cases may not be feasible unless the relevant authorities recognize the mission of an official UFO research organization (as has been done in France) and give the investigators clearance for access to some of the unexploited raw data. It would be necessary for the research organization to help implement adequate software modules that can read and store available data in a mode of operation that does not interfere with the primary mission of the system.
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