Philip Klass, who died Tuesday at 85, was among the leading investigators of reports of unidentified flying objects, a hard-core skeptic who spent decades showing they could be explained by astronomical phenomena, man-made technology, and outright deception.

Although he preferred not to be known as a debunker, because he claimed to be open to the possibility that a UFO report could turn out to be true, Klass was widely viewed among UFO enthusiasts as a killjoy or worse.

Among Klass’s most significant cases were reports of a crashed flying saucer at Roswell, N.M., in which several alien bodies were said to have been discovered; the purported existence of a super-secret government group known as MJ-12 set up by President Truman to deal with cases like Roswell and a series of mysterious sightings in New Zealand, some of which he was able to show were brightly lit Japanese squid boats.

In his book “The Real Roswell Crashed-Saucer Coverup” (1997), Klass uncovered masses of unclear and fabricated evidence. He was frustrated that television producers, even when they bothered to solicit his opinion, generally cut him out of their programs. The real cover-up at Roswell, he felt, was of convincing, non-alien explanations by the media. Klass concluded that most legitimate UFOs at Roswell could be identified as related to weather balloons, and that the rest of the evidence was faked.

“In nearly 30 years of searching, investigating famous cases, I have yet to find one that cannot be explained in down-to-earth prosaic terms,” Klass told interviewers for the PBS program “NOVA.”

Klass was born November 8, 1919, in Des Moines and graduated from Iowa State University in 1941 with a degree in electrical engineering. He went to work for General Electric, then took a job reporting for the magazine Aviation Week and Space Technology, the leading publication of the industry. He remained at Aviation Week for 34 years and wrote some of the first articles about inertial guidance technology, infrared missile guidance and detection, and the development of microelectronics. He is generally credited with having coined the term “avionics” for aviation electronics, which he rightly predicted would revolutionize the field.

Klass investigated his first UFO report in 1966, after a policeman in Socorro, N.M., reported seeing two extraterrestrials dressed in coveralls scurry into an egg-shaped spacecraft, which subsequently took off like a rocket. Klass found no evidence of aliens but plenty of evidence, such as a pre-existing plan to build a road to the site, that local officials were hoping to boost tourism. He eventually labeled the report a hoax.

Other cases were not so easy to explain away, including a series of reports from 1952 of anomalous radar blips and odd lights observed by pilots around Washington, D.C. Klass hypothesized that these were caused by temperature inversions, and in one case by car headlights observed by a pilot flying at low altitude.

Other cases were explained by phenomena as diverse as flaming meteors breaking up in Earth’s atmosphere, runaway kites, and glowing fireballs near high-power lines.

“I’ve found that roughly 97, 98 percent of the people who report seeing UFOs are fundamentally intelligent, honest people who have seen something – usually at night, in darkness – that is unfamiliar, that they cannot explain,” Klass said. The rest were frauds.

Klass wrote a half-dozen books detailing his investigations and published the monthly Skeptics UFO Newsletter. He was one of the founders of the Committee for the Scientific Investigation of Claims of the Paranormal and a frequent contributor to its main publication, Skeptical Inquirer.

Klass also published one of the first accounts of spy satellites, “Secret Sentries in Space” (1971). He continued to contribute to Aviation Week after his retirement in 1986.

In 1999, the International Astronomical Union honored him by formally changing the name of asteroid 1983 RM2/7277 to Klass.

Tall, gregarious, and eager to debate, Klass reminded some of a space-science version of Howard Cosell. Despite his skepticism, he was often to be found at conventions of UFO enthusiasts, where he claimed he frequently was thanked for requiring more rigor in reports of sightings. Scholars who propagated accounts of alien abductions, such as the Harvard psychologist John Mack, were less gracious about Klass’s dismissive attitude toward their work.

In a 1999 interview in the Skeptic magazine, Klass denied that he feared that some UFO reports might turn out to be true.

“As I turn 80, my fondest hope is that a genuine ET craft will land on our back patio and that I will be abducted,” he said, adding that he hoped the aliens would cure his health problems. “Of course, I would have to pay Stanton Friedman $10,000 – based on my longstanding wager that UFOs will never be proven real – but I would expect to become wealthy from the royalties of a new book titled ‘Why Me, ET?’ … I even keep my videocam near my bed in the hopes of being able to film a beautiful ‘Nordic-type’ ET extracting sperm ‘the old-fashioned way.'”