Returning from the war, he took a position as assistant to S. W. Thurston, president of Western Hotels, Inc. (later Western International Hotels, then Westin Hotels). Within a year he had been named vice president, then became successively executive vice president (1953), president (1960), and finally chairman and CEO (1969). Westin merged with United Airlines in 1970, and Carlson became CEO of the newly formed company, UAL Corporation, a position he held from 1971–1979. In his first two years, he turned the nearly bankrupt airline profitable.