Incident No. 135 — Between 15 and 20 August 1947, 2130 Hours, Weaver, South Dakota.
An Air Force Officer saw twelve "flying discs" four miles away over the Rapid City Air Force Base in a tight diamond formation at 6000 to 10,000 feet descending to 6000 feet at 500 MPH. Objects made a formation turn and climbed at 30° to 40° accelerating. Objects were very maneuverable, remaining equally spaced in all maneuvers. Each object was 100 feet in length, oval-shaped and brilliant yellowish-white. No sound nor exhaust trail were heard or seen.
AMC Opinion: This reporter should be a reliable observer. However, it has been shown that distance cannot be estimated without prior knowledge of the size of an object. If distance is not known, speed cannot be estimated. More notable perhaps is that such minute detail could be remembered in a report made one year after the observation and yet the date was not remembered. Dr. Hynek suggested the possibility of detached auroral streamers.