In answer to reported UFO sightings, the United States Air Force began Project Blue Book, an investigation which attempted to determine whether or not these sightings were really extraterrestrial craft and, if so, whether or not they posed a thread to U.S. national security. Created by Dragnet Star Jack Webb, Project UFO was a sci-fi drama based upon the real life investigation and reportedly used the actual Project Bluebook files for story ideas.
I saw Project UFO as a kid and as I recall this show was a lot like some of the other shows Jack Webb was involved in, real to life and focused upon the less glamorous side of being an investigator. Although the sequences that showed the UFOs were well produced and featured great model work, the show's subject was the investigation, complete with dramatized interiews, scientific reasearch and the kind of real-life footwork that investigators do every day.
Of course the investigators would generally debunk the UFO in question as something other than an extra terrestrial craft, but often the final act would feature the same UFO in a different setting which would lead the viewer to question whether or not the investigator's determination were correct. Thus, Believers were allowed to continue believing and doubters were allowed to doubt.
This was an OK show, but like a lot of science fiction based shows in the 70s, it never really found a strong audience and did not last long. I think that might have found a following if cable TV had been commonplace when it was produced but back in the day two seasons was a pretty good run for a show like this.