Conclusions:
In view of the multiple radar sightings involved in this case, any conventional explanation for the occurrences reported would seem to require some sort of radar anomalous propagation. As pointed out in Chapter 7, the evidence for anomalous propagation in this case is rather uncertain. The temporary disappearance of the target as it appeared to overfly the ....[C] GCA is quite suggestive of anomalous propagation. The generally clear weather was conducive
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to the formation of the atmospheric stratification that causes anomalous propagation, although it by no means follows that such formation would have actually occurred. In this connection, the apparent near-coincidence between the appearance of broken clouds (0330 GMT) and the disappearance of the radar targets (0330 GMT) could be significant.
On the other side must be balanced the generally continuous and consistent movements of the radar tracks reported by . . .[A], which are not at all typical of radar false targets caused by anomalous propagation. In addition, some of the maneuvers reported in the radar controller's letter to have been executed by the UFO are extremely unlikely to be duplicated by a false target, in particular stopping and assuming a new path after following the intercepting aircraft for some time. The comments of the Air Force officer who prepared the UFO message reproduced earlier are also significant.
In an early Air Force investigation it was suggested that the visual sightings might have been caused by the Perseid meteors. However, as Air Force Consultant Dr. Hynek pointed out:
It seems highly unlikely, for instance, that the Perseid meteors could have been the cause of the sightings, especially in view of the statement of observers that shooting stars were exceptionally numerous that evening, thus implying that they were able to distinguish the two phenomena. Further, if any credence can be given to the maneuvers of the objects as sighted visually and by radar, the meteor hypothesis must be ruled out.
Dr. Hynek also remarked:
The statement that radars reported these facts to occur at later hours than the ground observers' needs clarification inasmuch as it
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contradicts other portions of the report which indicate that at least at certain times visual and radar sightings were simultaneous.
In retrospect it appears that what the statement in question may have been meant to imply was that the radars continued to report target(s) after visual contact had been lost; the statement does not necessarily imply that no simultaneous radar-visual sightings occurred.
In conclusion, although conventional or natural explanations certainly cannot be ruled out, the probability of such seems low in this case and the probability that at least one genuine UFO was involved appears to be fairly high.