Classicly

At a conference with Air Force officials in Washington in April 1952, he presented his idea that planetary mirages, sundogs, reflections, and other astronomical, atmospheric, and optical phenomena probably accounted for a large percentage of the mysterious UFOs. This suggestion met with strong skepticism from some of the conferees who at that time were sympathetic to the interplanetary hypothesis and were, of course, better acquainted with military than with physical science.

Other conferees, however, wished to consider and test the theories offered. Proof obviously required a knowledge of all the facts of a given sighting, facts that often were not available to the public. The Air Force therefore granted access to the file of UFO cases. At the same time, since many of the cases were then classified as secret, the Air Force imposed the condition that security regulations must be strictly observed.