Hynek was the lead scientific consultant to the US Air Force project Blue Book from its inception in 1948 until its dissolution in 1969. He was hired to examine official UFO reports and advise on likely astronomical explanations. With his security clearance he was aware of the highly-classified Robertson Panel report, and the shift thereafter within Blue Book from active interest to 'provide an explanation no matter how absurd'.
Hynek spent 20 years reviewing over 10,000 reports collected by the US Air Force. This made him the most experienced and knowledgeable UFO researcher of all time. The accumulated evidence persuaded him that something was indeed going on here. He detected patterns in the sightings, indicating there was some underlying reality.
After the end of all public US government interest in UFO's, Hynek decided the research must be continued by private researchers. In 1972 the published The UFO Experience: A Scientific Inquiry, which laid out the evidence for the reality of the phenomenon. Hynek classified UFO sightings into five categories in that book:
Turning then to the content of UFO reports, let us assume that we have eliminated all those reports which do not fit the definition of a UFO as used earlier, that is, the dross from the original mass of "raw" reports -- all reports that can be explained with good reason as balloons, aircraft, meteors, etc. (Such reports represent the "garbage" in the problem. If we incorporate that in our studies, the computer-age adage, "Garbage in -- garbage out," will surely apply. This has been the trap that UFO investigations in the past have not been able to avoid.After the book came out, Hynek founded the Center for UFO Studies (CUFOS) to continue research along the lines he envisaged. CUFOS managed to obtain the unfinished mainframe computer database of UFO sightings that a Condon Report researcher had assembled from USAF reports. It did indeed prove difficult to code reports according a Hynek Probability Rating. Instead the number of witnesses, and if there were multiple independent witnesses, was recorded. In any case, in the post-Watergate era the criteria of 'solid reputation' being equivalent to veracity did indeed seem untenable.
In terms of scientific study, the only significant UFO reports are, as we have seen, UFO reports that remain puzzling after competent investigation has been conducted. Only these can be termed reports of UFOs. The stimulus for these reports is truly unknown -- that is, the reporters have passed a reliability screening, and the known possible stimuli have passed a physical explanation screening. Thousands of such reports exist; there are about 700 acknowledged cases in Blue Book files alone, and many others are contained in the files of UFO organizations and private investigators.
Each such screened report demands an answer to two distinct questions: What does it say happened? What is the probability that it happened? We can make those two questions the basis of a very helpful two-dimensional arrangement of UFO reports. Each report that has satisfied the definition of UFO used in this book can be assigned two numbers: its Strangeness Rating and its Probability Rating.
The Strangeness Rating is, to express it loosely, a measure of how "odd-ball" a report is within its particular broad classification. More precisely, it can be taken as a measure of the number of information bits the report contains, each of which is difficult to explain in common-sense terms. A light seen in the night sky the trajectory of which cannot be ascribed to a balloon, aircraft, etc. would nonetheless have a low Strangeness Rating because there is only one strange thing about the report to explain: its motion. A report of a weird craft that descended to within 100 feet of a car on a lonely road, caused the car's engine to die, its radio to stop, and its lights to go out, left marks on the nearby ground, and appeared to be under intelligent control receives a high Strangeness Rating because it contains a number of separate very strange items, each of which outrages common sense.
As we have seen, in the absence of hard-core evidence in the form of movies, detailed close-up shots, and so forth, we must depend greatly on the credibility of the principal reporter and his witnesses. Clearly, a report made by several independent persons, each of obvious sanity and solid general reputation, deserves more serious attention as probably having actually happened than a report made by a lone person with a none too savory record for veracity in past dealings with his fellow man.
This still leaves open a wide range of probability as to whether the strange event occurred as stated. Several judgment factors enter here as to whether what these otherwise reputable people reported on a particular occasion can be accepted -- and with what probability. How much would one 'bet," even considering the qualifications of the reporters, that what was reported really happened as reported?
Assessment of the Probability Rating of a report becomes a highly subjective matter. We start with the assessed credibility of the individuals concerned in the report, and we estimate to what degree, given the circumstances at this particular time, the reporters could have erred. Factors that must be considered here are internal consistency of the given report, consistency among several reports of the same incident, the manner in which the report was made, the conviction transmitted by the reporter to the interrogator, and finally, that subtle judgment of "how it all hangs together." It would be most helpful in the Probability Rating assignment if "lie detector" and other psychological tests were available. Likewise, a doctor's statement on the state of the reporter's health at the time or information of any severe emotional disturbance just prior to the time of the reported event would be helpful. Ideally, a meaningful Probability Rating would require the judgment of more than one person.
Such luxury of input is rarely available. One must make do with the material and facilities at hand. In my own work I have found it relatively easy to assign the Strangeness number (I use from 1 to 10) but difficult to assign a Probability Rating…. I do not consider a Probability Rating greater than 3 to any report coming from a single reporter, and then only when it is established that he has a very solid reputation…
Over the years CUFOS supplemented the database, and in the process created additional categories, some of them for abnormal phenomena not necessarily related to UFO's:
CUFOS fought on uphill battle. After the Condon Report the media and government portrayed any believers in the UFO phenomena as nut cases. In 1977 Star Wars and Close Encounters of the Third Kind opened up in theaters and became the most popular movies ever made up to that time. Close Encounters was based on Hynek's and Vallee's work and should have stimulated public interest in UFO's. Instead it unleashed a flood of high-budget, big-box office films covering multiple present and future universes teeming with spacefaring extraterrestrial life. This fantasy universe was so much more interesting than the real one that funding and public interest in actual space exploration and actual UFO studies totally collapsed. What once seemed a possibility was now reduced to a juvenile fantasy. Funding for NASA nearly dried up, and contributions and interest in actually studying UFO's almost ended as well. In 1982 CUFOS had to pull the plug on their UFO database.
Hynek passed away at his home of a brain tumor on 27 April 1986. CUFOS has soldiered on over the years in reduced form, but UFO sightings were merged into a semi-coherent mythos that included Nazi saucers, Area 51 alien autopsies, shadowy Men In Black, alien abductions, cattle mutilations, Majestic-12 committee world domination, and cover-ups of black aircraft programs. Encountering a UFO became the most mundane portion of this mythos and of little public interest.
In a way, Hynek succeeded, in that polls show that the vast majority of the public believes that UFO's exist. In another, he failed, in that his hoped-for scientific respectability and study of the phenomena never came to pass.