MITCHEL AFB, NEW YORKJanuary 1952

On January 21, 1952, a U.S. Navy pilot flying a TBM aircraft near Mitchel Air Force Base in New York spotted an unusual object at low altitude. The pilot estimated it was traveling at 300 knots and was located about halfway between his plane and the end of a nearby runway. At first, he thought it was a parachute, though he noticed it was moving crosswind, which made him reconsider. The object appeared dome-shaped or like a parachute canopy, light colored on top and darker underneath, with a length-to-depth ratio of about 1 to 3. While the object was in level flight, it seemed to oscillate slowly.

When the pilot tried to intercept the object, he began a left turn and kept his airspeed at about 160 knots. The object stayed mostly below his aircraft during the chase. After roughly two and a half minutes, the object appeared to climb rapidly, accelerating to an estimated 500 knots, and then vanished from sight when it reached an angle of about 10 degrees above the pilot's eye level. The object did not gradually fade into the distance, the pilot said, it simply disappeared. He was particularly certain that at one point when he was flying north of the airfield, he could still see the object.

Investigators learned that the Mitchel Air Force Base weather station had launched a Rawinsonde balloon (a weather balloon used to measure atmospheric conditions) at 0950 EST that same morning from a position near the runway. The balloon was about six feet in diameter at launch and was tracking upward. Its path and altitude at the time of the sighting roughly matched the object's position, and investigators calculated that a six-foot balloon at certain distances could appear to match the pilot's size estimates. The balloon's surface was light gray with white streaks of talcum powder used in packing it, which could create the "panel" effect the pilot thought he saw. A radar reflector made of aluminum foil hung beneath it.

However, significant gaps remained. The pilot was confident he had been north of the airfield when he still saw the object, which would have been difficult to reconcile with the balloon's actual track. He also stated that near the end of the encounter, the line of sight began swinging toward his aircraft's nose, which might have brought him close enough to identify a balloon. The pilot's sketch of the chase also contained discrepancies, appearing to show a much larger turning radius than his stated airspeed and G-forces would allow. The Air Force concluded in its investigation that while enough data correlated with the balloon theory to suggest it as a possibility, it could not be definitively proven that the object sighted was the Rawinsonde balloon.

The full case file, comprising 10 pages held by the National Archives, is reproduced below.