Montevideo, Uruguay, December 1958December 1958

On the night of December 7, 1958, a man in Montevideo, Uruguay saw seven flying saucers pass silently overhead. The observer was standing in a high, dark location in the city at 11:15 p.m. when he spotted the objects moving toward the northeast at an estimated altitude of 2,000 meters (roughly 6,500 feet). They traveled at approximately 1,500 kilometers per hour and covered a 45-degree arc of sky in just six seconds.

The objects flew in loose formation, with five grouped together and two trailing slightly ahead to the right. What struck the observer most was that they did not rotate on their axes, since he could clearly see two dark spots beneath each one, which would have been impossible if they were spinning. The craft appeared to be dull wood-colored and had no light of their own, visible only because city lights reflected faintly off them from below. The observer noted that all seven objects moved together as a single unit, suggesting they were somehow connected by a force binding them together.

The witness was a qualified observer. He held a pilot's license with 25 years of aviation experience and was 40 years old at the time. During a radio interview arranged by a local UFO research group, he appealed for other witnesses to come forward, but no one else reported seeing the objects. The investigative report notes that this is unsurprising, since special conditions were required to see them: an observer had to be in complete darkness at an elevated location in the city. The case file compares the irregular formation to a famous film shot in Utah, United States, which also showed multiple saucers moving together in an unusual pattern.

The Air Force marked the case as "unknown" in its evaluation. The complete case file, comprising 9 pages, is reproduced below as held by the National Archives.