Boston Air Defense Sector Pease AFB, N. H., May 1959May 1959

On May 1959, radar operators at the Boston Air Defense Sector near Pease Air Force Base in New Hampshire detected an unusual cluster of blips on their screens. Around 0023Z (just after midnight), five radar tracks appeared with no corresponding flight plans. The objects showed speeds between 200 and 400 knots and flew at altitudes ranging from 7,000 to 18,000 feet, with most clustered around 10,000 feet.

Within minutes, more tracks appeared about 60 miles east of Boston. The radar network tracked a total of 18 targets, some climbing as high as 36,000 feet. The Air Force scrambled ten interceptor aircraft from three nearby bases, Stewart, Westover, and Otis, to pursue the unknowns. Four aircraft were already airborne when the call came. Despite the best efforts of the pilots, all the radar blips faded before any visual or radar contact could be made. Most of the targets vanished between 0923Z and 0947Z, though a few were later identified: two Navy aircraft, one Boeing 707 transport, and one RC-121 reconnaissance plane.

Investigators checked every radar set in the sector, verified the computer systems with help from IBM, and confirmed that all equipment was functioning normally. They also checked for known air traffic with New York and Boston air traffic control and coordinated with the Eastern NORAD region. All radar sites showed good tracking data, and several stations simultaneously tracked the same targets, ruling out a single faulty antenna. The Air Defense Artillery unit also picked up six of the targets on their own radar and took height readings to verify the sightings.

Weather conditions that night offered little explanation. Scattered clouds hung between 8,000 and 10,000 feet, and a weather balloon sounding taken at Nantucket showed such a small change in the atmosphere's refractive index that radar ducting (a phenomenon where radar waves bend and create false images) was deemed impossible.

The Air Force concluded that the fourteen unidentified tracks almost certainly represented false radar targets, though investigators acknowledged uncertainty. They reasoned that since no interceptor made contact despite eight scramble attempts, the targets were probably not real aircraft. However, the final analysis noted that many radars do display unexplained returns, and some peculiar transmission characteristic might have been responsible. The file does not resolve the cause definitively.

The full case file, totaling 9 pages as held by the National Archives, is reproduced below.