Dillon, MontanaApril 1949

On April 3, 1949, four people in Dillon, Montana, reported seeing a metallic, disk-shaped object at around 1150 hours (11:50 a.m.) in the northern sky above the city. The object appeared roughly twenty feet in diameter, with a thickness of four to five feet through the center. According to the witnesses, the top was bright and reflective, while the bottom had a bluish-gray or greenish-gray color that did not reflect light. The witnesses described the object as resembling two plates placed one on top of an inverted plate, with very thin edges and considerable thickness in the middle.

The object displayed unusual motion. It rocked or rotated in a semicircular pattern as it moved easterly, then descended rapidly from an altitude of three to five thousand feet to around seven hundred to one thousand feet. After rocking again, it moved rapidly in a southwesterly direction to a position two miles west of Dillon at about one thousand feet altitude. The object then climbed rapidly to above Dillon's airport, reaching an altitude of roughly one thousand feet and a position twelve miles northeast of the city. It rocked several more times before disappearing rapidly over the mountains east of Dillon. The witnesses reported the object made no sound, produced no exhaust or smoke, and traveled faster than one thousand miles per hour, moving so fast it appeared to blur.

The investigation found no evidence of exhaust, smoke, odor, or sound. Visibility was approximately forty miles that day, and the sky was clear. The object showed no protruding fins, stabilizers, slots, or duct openings. The case file notes that the primary observer owned and operated a construction company and was regarded by local law enforcement, banking officials, and community leaders as reliable and beyond reproach. Three additional witnesses, including a gas station attendant, a construction company employee, and a truck company operator, corroborated the sighting with slight variations in estimated diameter (fifteen to twenty-five feet). Weather data and wind aloft information were collected and attached to the file. The Air Force investigation was closed after all logical leads were exhausted, though the case file itself does not state a definitive conclusion about what was observed.

The full case file is reproduced below as held by the National Archives, spanning 14 pages.