Klass’ first job was working on aviation electronics systems for General Electric during World War II.He is credited with coining the term “avionics” and went on to become the first avionics editor of Aviation Week & Space Technology, the premiere journal of the aviation industry.

Klass is largely considered the most famous skeptic within ufology and wrote several books critical of UFOs. Perhaps because of his immersion in the reality-based world of aviation and science, Klass did not automatically give credence to claims of flying saucers and alien abduction which first began proliferating in the late 1950s and early 60s.

Klass inspires polarized appraisals in both the ufological and skeptical communities, and had a reputation as  the “Sherlock Holmes of ufology”. In 1999, Skeptical Enquirer named him number five on their list of top skeptics of the 20th century.

In 1966, Klass offered a $10,000 reward if certain conditions proving UFOs were met, which remained unclaimed at his death.  Klass left a particularly damning statement towards his critics titled The Last Will and Testament of Philip J. Klass, originally published in Saucer Smear in October 1983:

“To ufologists who publicly criticize me, … or who even think unkind thoughts about me in private, I do hereby leave and bequeath: THE UFO CURSE: No matter how long you live, you will never know any more about UFOs than you know today. You will never know anymore about what UFOs really are, or where they come from. You will never know anymore about what the U.S. Government really knows about UFOs than you know today. As you lie on your own deathbed you will be as mystified about UFOs as you are today. And you will remember this curse.”