Delta Air Lines, Inc. provides scheduled air transportation for passengers and cargo in the United States and internationally. The company operates through two segments, Airline and Refinery. Its domestic network centered on core hubs in Atlanta, Minneapolis-St. Paul, Detroit, and Salt Lake City, as well as coastal hub positions in Boston, Los Angeles, New York-LaGuardia, New York-JFK, and Seattle; and international network centered on hubs and market presence in Amsterdam, Bogota, Lima, Mexico City, London-Heathrow, Paris-Charles de Gaulle, Sao Paulo, Seoul-Incheon, and Tokyo. The company sells its tickets through various distribution channels, including delta.com and the Fly Delta app; acts as a reservations specialists; and operates online travel and traditional brick and mortar agencies. It also provides aircraft maintenance and engineering support, repair, and overhaul services; and vacation packages to third-party consumers. The company operates through a fleet of approximately 1,273 aircrafts. Delta Air Lines, Inc. was founded in 1924 and is based in Atlanta, Georgia.

United Airlines Holdings, Inc., through its subsidiaries, provides air transportation services in North America, Asia, Europe, Africa, the Pacific, the Middle East, and Latin America. The company transports people and cargo through its mainline and regional fleets. It also offers catering, ground handling, flight academy, and maintenance services for third parties. The company was formerly known as United Continental Holdings, Inc. and changed its name to United Airlines Holdings, Inc. in June 2019. United Airlines Holdings, Inc. was incorporated in 1968 and is headquartered in Chicago, Illinois.

Southwest Airlines Co. operates as a passenger airline company that provides scheduled air transportation services in the United States and near-international markets. As of December 31, 2023, the company operated a total fleet of 817 Boeing 737 aircraft; and served 121 destinations in 42 states, the District of Columbia, and the Commonwealth of Puerto Rico, as well as ten near-international countries, including Mexico, Jamaica, the Bahamas, Aruba, the Dominican Republic, Costa Rica, Belize, Cuba, the Cayman Islands, and Turks and Caicos. It also provides inflight entertainment and connectivity services on Wi-Fi enabled aircraft; and Rapid Rewards loyalty program that enables program members to earn points for dollars spent on Southwest base fares. In addition, the company offers a suite of digital platforms to support customers' travel needs, including websites and apps; and SWABIZ, an online booking tool. Further, it provides ancillary services, such as Southwest's EarlyBird Check-In, upgraded boarding, and transportation of pets and unaccompanied minors. Southwest Airlines Co. was incorporated in 1967 and is headquartered in Dallas, Texas.

Alaska Air Group, Inc., through its subsidiaries, operates airlines. It operates through three segments: Mainline, Regional, and Horizon. The company offers scheduled air transportation services on Boeing jet aircraft for passengers and cargo in the United States, and in parts of Canada, Mexico, Costa Rica, Belize, Guatemala, and the Bahamas; and for passengers across a shorter distance network within the United States, Canada, and Mexico. Alaska Air Group, Inc. was founded in 1932 and is based in Seattle, Washington.

SkyWest, Inc., through its subsidiaries, engages in the operation of a regional airline in the United States. It operates through two segment, SkyWest Airlines and SWC; and SkyWest Leasing. The company is also involved in leasing regional jet aircraft and spare engines to third parties; and provision of on-demand charter, airport customer, and ground handling services. As of December 31, 2023, its fleet consisted of 603 aircraft; and provided scheduled passenger and air freight services with approximately 1,850 total daily departures to various destinations in the United States, Canada, and Mexico. SkyWest, Inc. was incorporated in 1972 and is headquartered in Saint George, Utah.

Air Transport Services Group, Inc., together with its subsidiaries, provides aircraft leasing, and air cargo transportation and related services in the United States and internationally. It operates in two segments, Cargo Aircraft Management Inc. (CAM) and ACMI Services. The company offers aircraft, flight crews, aircraft hull and liability insurance, and aviation fuel services; and aircraft maintenance and modification services, including airframe modification and heavy maintenance, component repairs, engineering services, and aircraft line maintenance. It also provides equipment maintenance services; cargo load transfer and package sorting services; crew training services; and airline express operation, line and heavy maintenance, and ground handling services. The company's ground support services include labor and management for cargo load transfer and sorting; design, installation, and maintenance of material handling equipment; leasing and maintenance of ground support equipment; general facilities maintenance; and resells aviation fuel at the air park in Wilmington, Ohio. Further, the company operates cargo and passenger transportation business; resells and brokers aircraft parts; and performs passenger-to-freighter and passenger-to-combi conversions of aircraft. It provides its services to delivery companies, freight forwarders, airlines, air transportation, e-commerce, package delivery, and logistics industries, as well as government customers. As of December 31, 2023, the company's in-service aircraft fleet consisted of 107 owned Boeing aircraft, three Airbus aircraft, and 20 leased aircraft. The company was formerly known as ABX Holdings, Inc. and changed its name to Air Transport Services Group, Inc. Air Transport Services Group, Inc. was founded in 1980 and is headquartered in Wilmington, Ohio.