Complex sentence: In September 1977, then Colonel Williams was assigned as the Vice Wing Commander of the 81st TFW at RAF Bentwaters, England, and was promoted to Wing Commander in August 1979 and was the commander at the time of the alleged UFO incident in December 1980.
Split into simpler sentences: In September 1977, then Colonel Williams was assigned as the Vice Wing Commander of the 81st TFW at RAF Bentwaters, England, and was promoted to Wing Commander in August 1979. He was the commander of the 81st TFW at the time of the alleged UFO incident in December 1980.