Conclusions et recommandations pour travail ultérieur

Thayer, Gordon D.Thayer, Gordon D., 1968

The following conclusions can be stated as a result of the investigation reported in this chapter:

  1. Anomalous Propagation (AP) effects are probably responsible for a large number of UFO reports in cases involving radar and visual sightings.
  2. There are two common patterns that are evidenced in radar-visual cases involving anomalous propagation effects:
    1. Unusual AP radar targets are detected, and visual observers are instructed where to look for apparent UFOs and usually "find" them in the form of a star or other convenient object.
    2. Unusual optical effects cause visual observers to report UFOs and radar operators are directed where to look for them. As above, they usually "find" them, most often in the form of intermittent AP echoes, occasionally of the unusual moving variety.
  3. In radar-visual UFO sightings there is a pronounced tendency for observers to assume that radar and visual targets are correlated, often despite glaring discrepancies in the reported positions. There is a perhaps related tendency to accept radar information without checking it as carefully as the observer might normally do; hence errors are promulgated such as, direction of UFO movement confused with the azimuth at which it was observed on the radar scope, and UFO speed reported that is grossly at variance with plotted positions at times (both of these effects are well illustrated in Case 93-B).
  4. There is a general tendency among even experienced visual observers to grossly over-estimate small elevation angles. Minnaert (1954) states that the average "moon illusion" involves a factor of 2.5-3.5. The results of the present investigation imply that objects at elevation angles as small as 1° are estimated to be at angles larger than the true value by at least this factor or more. Interestingly, all of the elevation angles reported of visual objects in the cases examined in this chapter, not a single one is reported to be less than 10°. The fact that radar may subsequently "see" the UFOs at angles of only 1° to 4° seems not to bother the visual observers at all; in fact when the visual observers report apparent height-range, these values often turn out to be equivalent to elevation angles of only a degree or two. There seems to be a sort of "quantum effect" at work here, where an object must be either "on the horizon" (i.e., at 0° or at an elevation of greater than 10°.
  5. There are apparently some very unusual propagation effects, rarely encountered or reported, that occur under atmospheric conditions so rare that they may constitute unknown phenomena; if so, they deserve study. This seems to be the only conclusion one can reasonably reach from examination of some of the strangest cases (e.g., 190-N, 5 and 21).
  6. There is a small, but significant, residue of cases from the radar-visual files (i.e., 1482-N,Case 2) that have no plausible explanation as propagation phenomena and/or misinterpreted man-made objects.

A number of recommendations for future UFO investigative procedures are indicated by the results of this chapter:

  1. In any investigation of a UFO report, extremely careful efforts should be made to determine the correct azimuth and elevation angles of any visual or radar objects, by "post mortem" re-creation of sightings if necessary. This information is probably more useful in analysis of the case than the description of the objects or targets.
  2. Reported speeds and directions of UFOs, especially of radar UFOs, should be carefully checked (again, "post mortem" if necessary) and cross-checked for validity. This information is also often critical for subsequent analysis.
  3. Every effort should be made to get the most comprehensive and applicable meteorological data available for an UFO incident as quickly as possible. Many types of weather data are not retained permanently, and it is difficult or impossible to retrieve the appropriate data for a sighting months or years after the fact. Copies of original radiosonde recordings should be obtained for the closest sites, since these may be analyzed in more detail than that routinely practiced by weather bureaus for synoptic purposes. It should be emphasized that, for example, a nighttime profile is usually more germane to a nighttime sighting than is a daytime profile. For example, if an UFO incident occurs at 2100 or 2200 LST, an 0600 LST (next day) raob will generally be more pertinent to the propagation conditions involved than will an 1800 LST raob. The converse is also true.
  4. Any field team investigating UFO reports and seeking to explore all radio/optical propagation aspects of the sighting (a highly desirable goal), should be equipped with the following personnel as a minimum:
    1. An expert on the unusual aspects of electromagnetic wave propagation, at both radio and optical wave lengths;
    2. An expert in the interpretation and theory of radar targets, who is acquainted with all types of anomalous propagation and other spurious radar returns;
    3. An expert with wide experience in the physiology and psychology of human eyesight, and familiarity with optical illusory effects, etc.;
    4. A meteorologist, with specialized experience in micro-meteorology-climatology, mesoscale meteorology, and atmospheric physics.