Incident #136 Sighting Report — South Knoxville, Tennessee, 30 June 1948

This document compiles reports and evaluations regarding Incident #136, a sighting of an unidentified aerial phenomenon in South Knoxville, Tennessee, on 30 June 1948. At approximately 2140 hours, witnesses observed a ball of fire, described as orange in color with a bluish trailing streamer, moving in a westerly direction before disappearing over the horizon. The incident was investigated by the Air Materiel Command as part of Project Sign. Two primary witnesses provided conflicting accounts of the duration of the sighting: one reported it lasted three minutes, while another reported it lasted only three seconds. The latter estimate was favored by investigators as being more consistent with meteoric phenomena, noting that observers are prone to overestimating time intervals. The official evaluation concluded that the sighting was a typical fireball. The document also includes broader administrative correspondence from the Air Materiel Command to the Air Weather Service, discussing the collection and investigation of such sightings and the role of the U.S. Weather Bureau in identifying potential balloon-related incidents. Additionally, the file contains an incident index and various internal communications regarding other sightings, including reports from Turkey and the Soviet Union, which were also being monitored under Project Sign. The documentation reflects the systematic, albeit early, efforts of the U.S. Air Force to categorize and explain aerial phenomena, often by cross-referencing them with known astronomical or meteorological events.