Traditional airlines, also known as legacy carriers, are the oldest airlines that were established in the 1920s and 1930s in the United States and Europe. They have a diversified network of both domestic and international flights, which includes short, medium, and long-haul flights. This network often includes hubs, which allow flights to converge on a connecting point, resulting in better aircraft load factors. Traditional airlines offer different service levels, catering to different segments of the market, such as business travellers who are looking for efficiency and comfort, and tourists who are more price-sensitive. These airlines are also referred to as flag carriers, to demonstrate their connection with the countries in which they were founded, or full-service carriers because of the wide range of services offered.
In order to counter the growing competition, traditional airlines have consolidated and merged with other one another. Several large international alliances have also been formed, such as the Star Alliance, Skyteam, and Oneworld. These alliances bring together the main American, European and Asian airlines. In the United States and Europe, the trend has been towards further consolidation, with only a few major companies or groups remaining on each side of the Atlantic, such as American Airlines, United and Delta in the US, and IAG (British Airways and Iberia), Lufthansa and Air France-KLM in Europe.