Uruguay, June 1957June 1957

In June 1957, a woman in Campanero, in the Lavalleja Department of Uruguay, reported seeing an unusual object in the sky. She described it as solid in appearance, round or slightly flattened in shape, and apparently made of metal. The object was blue-grey in color and brilliantly luminous. It moved across the sky at a uniform speed from south to north, traveling at an estimated distance of about four miles away. The witness noted an odd detail: the object produced a shrill, high-pitched sound, which she described as a pronounced whistle or chirp.

The observation form completed by Uruguayan authorities at CIOVI (Centro de Investigacion de Objetos Voladores Inidentificados, or Center for the Investigation of Unidentified Flying Objects) provides limited details about the sighting itself. The OCR text on the form is heavily degraded and difficult to read in many sections. No duration of observation or precise time was reported. The witness did mention that the windows of her house vibrated during the event.

In their analysis, CIOVI investigators noted that the case rested on three key facts: the solid appearance of the object, its round and flattened shape, and the witness's statement that it was metallic. They highlighted the unusual auditory element, comparing the sound to similar reports from other cases in Uruguay. They concluded that the evidence pointed to a flying saucer, though the file offers no supporting scientific analysis or alternative explanations. The Air Force's official evaluation was listed as "Probably Balloon," though this determination does not appear to be explained anywhere in the case materials.

The full case file, consisting of 8 pages as held by the National Archives, is reproduced below.