Complex sentence: It operated code sharing flights on behalf of Trans World Airlines (TWA) as Trans World Express, on behalf of US Airways as US Airways Express, on behalf of Midwest Airlines, on behalf of Ozark Air Lines and also as Mesa Airlines.
Split into simpler sentences: It operated code sharing flights on behalf of Trans World Airlines (TWA) as Trans World Express and on behalf of US Airways as US Airways Express. It also operated flights on behalf of Midwest Airlines and Ozark Air Lines and also as Mesa Airlines.