Philip J. Klass was born the son of a lawyer in Iowa. He attended Iowa State, earning a degree in electrical engineering which he put to good use working for the aviation department of General Electric. In 1955, he became a journalist, though remained close to aviation spending the next 50 years working at Aviation Week & Space Technology magazine. He spent over 30 years as a senior editor and the rest as a contributing avionics editor. He won several awards for his writing.

Science was a love from childhood, when he would build crystal radio sets. He once won a Boy Scout contest by building his own autogyro (helicopter). And yes: he flew it.

In addition, and for what he is probably best known, Klass was a tireless UFO skeptic who published several books debunking UFO sightings. He was also a founding member(and Fellow) of the Committee for Scientific Investigation of Claims of the Paranormal (CSICOP) in the 1970s. He also would write for its magazine The Skeptical Inquirer (originally titled The Zetetic). Klass also published the bimonthly Skeptics UFO Newsletter.

He once offered a $10,000 prize for anyone whose claims of seeing UFOs or being abducted could withstand the scrutiny of the FBI. Similar to fellow skeptic James Randi's $1,000,000 prize for verifiable proof of the paranormal, Klass' prize money was never paid out.

Klass died of prostate cancer 9 August 2005 at his home in Florida where he and his wife of 25 years lived.

His books:
UFOs—Identified 1968
Secret Sentries in Space 1971
UFOs Explained 1975
UFOs: The Public Deceived 1983
UFO Abductions: A Dangerous Game 1988
Bringing UFOs Down to Earth 1997 (for young readers)
The Real Roswell Crashed-Saucer Coverup 1997

Philip J. Klass' 10 UFOlogical Principles
(Paraphrased and adapted from his book UFOs: The Public Deceived, 1983, with some additions by me)

  1. When faced with an anomalous, unexpected, strange, unfamiliar, or frightening event/object, even intelligent, honest people may make mistakes, misinterpretations, and inaccurate statements about what they have witnessed.
  2. While Principle 1 is true, it does not mean descriptions and testimony can be dismissed out of hand. Even if errors or gross inaccuracies are present, some information may be accurate. The job of the investigator is to sift through and determine what is valuable and what is not. This may require an identification of the event/object before one can go back and reevaluate the information. Sometimes there will be no way to fully distinguish between the two.
  3. A person who, having witnessed an unusual or unfamiliar event/object, has determined personally that what was witnessed was a "spaceship from another world" will generally tend to believe the object in question is "reacting to his presence of movements," whether there is correlation or none at all (note: correlation does not equal causation; and in these cases, correlation, itself, may be dubious). Further: consider how when you are young and traveling in the back-seat at night—that moon sure seems to be following you doesn't it?
  4. The media will tend to give a highly disproportionate amount of coverage to stories of UFOs while giving little or none at all to "prosaic" explanations after the case and facts in the matter have been investigated.
  5. Despite how well one may be trained or how much experience one has in flight, a person cannot accurately estimate/determine distance/altitude or the size of unfamiliar objects (particularly when the viewing time is brief) in the sky unless it is in "very close proximity to a familiar object whose size and/or altitude is known." Estimation at night is subject to even greater inaccuracy despite the witness being honest, intelligent, and/or experienced (see Principle 1).
  6. When the media has announced (giving a sort of "official" stamp of approval) that UFOs may be in the locality, the public will be predisposed to "seeing" such phenomena and there will be sightings of "numerous natural and man-made objects which, especially when seen at night, can take on unusual characteristics in the minds of hopeful viewers." Reports, fueled by media accounts can create an excitement ("flap") that will encourage more hopeful amateur UFOlogists to search for anything that might be a confirmed sighting. This makes investigation more difficult until the flap runs out of energy and subsides.
  7. When investigating a report, the determination of whether there was something (even if it is "to be determined") or a hoax should rest on the physical evidence or lack thereof if there should be evidence left behind according to the story. It should not be dependent on the character of the person giving the testimony nor on endorsements of said character (i.e., Well, Jimmy Carter saw a UFO and he wouldn't lie. It must be true).
  8. "The inability of experienced investigators to fully and positively explain a UFO report for lack of sufficient information, even after rigorous effort, does not really provide evidence to support the hypothesis that spaceships from other worlds are visiting earth." (This is similar to the fallacious line of reasoning often taken by creationists who think if they poke enough holes in evolution their "theory" will be accepted, when in fact, they should be providing evidence of their own.)
  9. If a light is spotted in the night sky and believed to be a UFO, when it is reported to a radar operator who is told to look for an "unknown target," the likelihood he will find an "unknown target" is very high. Also, if a radar operator sights an unusual target on the scope at night, an observer dispatched to check is highly likely to report a visual confirmation of some sort. While not meaning no target exists, expectation and the fact that sometimes "unknowns" are spotted, it shouldn't be taken as proof of the sort of object UFOs tend to conjure up.
  10. "Many UFO cases seem puzzling and unexplained simply because case investigators have failed to devote sufficiently rigorous effort to the investigation."