Interline agreements are agreements between two or more airlines that allow them to cooperate in the sale and transport of passengers and cargo. These agreements allow airlines to offer connections to destinations that they do not serve directly, by selling tickets that include flights on both airlines.

For example, if an airline does not have a direct flight from New York to Los Angeles, it may enter into an interline agreement with another airline that does. The first airline can then sell tickets for the New York to Los Angeles route, with the second airline operating the leg of the journey between the two cities.

In the case of cargo, interline agreements allow airlines to transport goods to their final destination even if they do not operate flights to that destination. For example, an airline may transport goods from China to the United States and then transfer them to another airline for the final leg of the journey to a smaller city in the United States.

Interline agreements are common in the airline industry and are an important way for airlines to expand their networks and offer more travel options to their customers. However, not all airlines participate in interline agreements, and some have more limited agreements than others.