Philip J. Klass

Philip J. Klass was a senior editor at Aviation Week & Space Technology and the most prominent sceptical investigator of UFO claims in the United States for four decades. Beginning with his 1966 article proposing plasma explanations for UFO sightings, Klass systematically challenged cases that other researchers considered unexplained.

Klass published several books presenting sceptical analyses: UFOs: Identified (1968), UFOs Explained (1974), UFOs: The Public Deceived (1983), and UFO Abductions: A Dangerous Game (1989). His investigative method involved examining individual cases in detail, searching for prosaic explanations, and scrutinising witness credibility. He maintained a voluminous correspondence with researchers on all sides of the debate.

He engaged in prolonged public disputes with Stanton Friedman, Bruce Maccabee, and other UFO researchers. Klass offered standing cash challenges to anyone who could prove UFO claims, and he issued "UFO skeptics updates" to a mailing list of journalists, scientists, and researchers for decades.

Critics, including some fellow sceptics, argued that Klass sometimes reached for unlikely explanations to avoid acknowledging genuinely puzzling cases, and that his investigations could be as biased as those of uncritical believers. Supporters credited him with exposing hoaxes and forcing UFO researchers to raise their evidentiary standards. His papers were donated to the American Philosophical Society after his death in 2005.