[ILLEGIBLE], December 1948 - Incident Number: 216December 1948

On December 8, 1948, at 6:46 p.m., a bright round object was sighted near Chanute Air Force Base in Illinois by a professional weather observer. The object appeared roughly 15 feet across and was traveling at an estimated speed exceeding 350 miles per hour, moving northeast to southwest. The observer was standing on the ground facing northeast when a glint of light caught his attention.

The object moved upward at an angle of roughly 15 to 20 degrees above the horizon. Within 35 seconds, it traversed about 35 degrees of sky and then disappeared from view. The observer reported that the object seemed to get larger as it moved and was leaving a trail behind it. Weather conditions at the time included high scattered clouds and ten mile visibility. The object made no sound.

The sighting is particularly notable because the observer was a trained weather professional who would have been familiar with weather balloons. The observer noted that the object's speed and behavior seemed inconsistent with a balloon, and the sighting occurred four hours after the scheduled release time for weather balloons at the base. A second witness, another weather observer at the station, provided a similar account of the same object.

Subsequent Air Force correspondence noted tension between the observers' account and the possibility of a weather balloon. Air Weather Service officials reviewed the sighting against routine weather balloon ascents made by the Air Force, Navy, and Weather Bureau, though the precise conclusions of that review are unclear in the file. The Air Force evaluation of this incident is listed as unknown. The full case file, reproduced here as held by the National Archives, comprises 22 pages.