A legacy carrier, in the United States, is an airline that had established interstate routes by the time of the route liberalization which was permitted by the Airline Deregulation Act of 1978 and was thus directly affected by that act. It is distinct from a low-cost carrier (a term fostered as a form of disparagement against post deregulation start-up air carriers, and the traditional airlines once heavily unionized work groups), which in the United States are generally new airlines that were started to compete in the newly deregulated industry.
Typical characteristics of legacy carriers are that they provide a higher level of services than a low-cost carrier; for example, a legacy carrier typically offers first class and/or business class, a frequent-flyer program, airport lounges, and is a member of an airline alliance through which it has partners that agree to provide these services to its passengers as well. Also, there is a higher level of services in the cabin, such as meal service and in-flight entertainment.
Since the Deregulation Act and subsequent Chapter 11 bankruptcy, many legacy carriers have folded or merged with other carriers. Low-cost carriers which once held major cost advantages resultant from paying competitively low new carrier start-up wages, fleet simplicity, lack of expensive defined pension plans, and less employee friendly work rules when compared to legacy carriers no longer hold such expansive cost advantages when compared with the major nation and world wide airlines due to bankruptcy reorganization which they all have gone through. Among the remaining airlines with continent traversing major route networks, there are only 4 left now that United and Continental have consummated their merger.
- Delta Air Lines
- American Airlines
- United Airlines
- US Airways - merger with American pending
- Alaska Airlines
- Hawaiian Airlines
Regional carriers usually (incorrectly) considered "legacies";
Defunct carriers include:
- Continental Airlines, merged with United in 2011
- Western Airlines, merged with Delta
- Trans World Airlines, merged with American, 2001
- Pan American World Airways
- Northwest Airlines, merged with Delta, 2008, brand retired in early 2010 as it completed its merger with Delta
- National Airlines (NA)
- Eastern Air Lines
- Braniff International Airways