Airlines are definitely not an example of perfect competition. They are the number one textbook example of oligopolistic competition leading to price discrimin

Airlines are definitely not an example of perfect competition. They are the number one textbook example of oligopolistic competition leading to price discrimination. A given route between two cities only has so many airlines competing. They just have a tough time surviving because airports are monopolies (except in some major metros where there is limited competition), thus can capture most of the airlines' profits.