Wheelus AB, Libya, October 1956October 1956

On the night of October 17-18, 1956, radar operators at Wheelus Air Base in Libya detected two unidentified objects moving slowly through the airspace near the base. The objects appeared on both ground radar and the radar systems aboard F-86D fighter aircraft, but no pilot ever saw them visually, even when closing to within one mile.

The first object was picked up on ground radar at 17/2922Z (approximately 5:22 p.m. local time) at an altitude of about 9,000 feet. It maintained a heading of 210 degrees until 2303Z, when it changed course to 170 degrees and disappeared from radar. The second object appeared on the scope at 2317Z at a lower altitude of 5,400 feet, descending to about 3,800 feet before vanishing. Weather conditions that night were clear, with ten nautical mile visibility and no cloud ceiling.

Two F-86D aircraft were sent to intercept the first object. Both made solid radar contact but never achieved visual sighting. When the object changed heading, ground radar lost contact momentarily. Two more F-86D fighters pursued the second object, and one pilot reported that just before losing the radar signal, he was positioned just above, just below, or between clouds. Throughout both encounters, neither object took evasive action, and neither pilot ever saw anything with his own eyes.

The Air Force officers who prepared the report considered but rejected several explanations. They noted that flocks of migratory birds crossing the Mediterranean that season could produce radar returns, but a flock at 9,000 feet seemed unlikely, and repeated passes by fighter aircraft would probably have scattered it. They also doubted that weather effects like a temperature inversion (a layer of warm air trapping cold air below) could explain the strong, consistent radar signals. In a follow-up memo from February 1965, an Air Force electronics engineer noted that the pilots' failure to see anything visually, despite closing to less than a mile in clear visibility, suggested "there was no material target" and that some unusual atmospheric condition might have caused the radar returns instead. No final conclusion appears in the file.

The complete case file, as held by the National Archives, is reproduced below across 7 pages.