Air Intelligence Information Report: Unidentified Radar Sightings in Greenland

This Air Intelligence Information Report (IR-255-53), dated 27 March 1953, details an investigation into an unidentified radar sighting that occurred on 26 February 1953 at Thule Air Base, Greenland. At 0550Z, GCA (Ground Controlled Approach) operators, including S/Sgt George Smith and S/Sgt E. T. Lucas, observed a prominent blip on their PPI (Plan Position Indicator) scope. The object emerged from normal ground clutter, was tracked for three miles on a grid heading of 270 degrees, and faded from the scope at a distance of seven miles. The object's speed was estimated by the operators to be approximately 180 knots, and it maintained an altitude under 6,000 feet. A MATS C-124 aircraft, piloted by Captain Nelson, was in the vicinity at the time but did not visually observe any object, nor did the AC&W (Aircraft Control and Warning) radar system detect the target. Following an interrogation of the GCA personnel, investigators noted several discrepancies in the accounts regarding the object's speed, altitude, and tracking duration. The report concludes that the sighting was not a physical craft but rather a meteorological phenomenon. Specifically, the investigators attributed the radar return to a combination of temperature inversions—noted at 3,500 and 7,000 feet—and ice crystal condensation (vapor trails) from the C-124 aircraft, which created false radar reflections on the PPI scope. The report emphasizes that the failure of the AC&W system to detect the object further supports the conclusion that it did not exist as a solid, unidentified aerial vehicle.