“Reports of unusual activity in the skies in the ‘50s? It was us.”
High-altitude testing of the U-2…led to an unexpected side effect — a tremendous increase in reports of unidentified flying objects,” the CIA wrote in the document, which it wrote in 1998. “In the mid-1950s, most commercial airliners flew at altitudes between 10,000 and 20,000 feet and [many] military aircraft…operated at altitudes below 40,000 feet. Consequently, once U-2s started flying at altitudes above 60,000 feet, air-traffic controllers began receiving increasing numbers of UFO reports.”
Added the document, the CIA cross-referenced UFO sightings to U-2 flight logs. “This enabled the investigators to eliminate the majority of the UFO reports,” the CIA wrote, “although they could not reveal to the letter writers the true cause of the UFO sightings.”Read more "CIA takes blame for more than half of UFO sightings in late 1950s and 60s"