ATA Airlines, Inc. – formerly known as American Trans Air and commonly referred to as ATA – was an American low-cost scheduled service and charter airline based in Indianapolis, Indiana. ATA operated scheduled passenger flights throughout the U.S. mainland and Hawaii, Puerto Rico, and Portugal as well as military and commercial charter flights around the world. In its early days, the airline flew charters on a worldwide basis and had bases in Chicago, Detroit, New York, Indianapolis, Oakland, and Milwaukee. Later, when it entered scheduled service, the airline maintained focus cities at Chicago Midway International Airport, Honolulu International Airport, and Oakland International Airport.

Chicago Midway International Airport, typically referred to as Midway Airport, Chicago Midway, or simply Midway, is a major commercial airport on the Southwest side of Chicago, Illinois, located approximately 12 miles (19 km) from the city's Loop business district. Established in 1927, Midway served as Chicago's primary airport until the opening of O'Hare International Airport in 1944. Today, Midway is one of the busiest airports in the nation and the second-busiest airport both in the Chicago metropolitan area and the state of Illinois, serving 22,050,489 passengers in 2023.