Interlining - Agreements

Agreements

Interlining agreements differ from codesharing agreements in that codesharing agreements usually refers to numbering a flight with the airline's code (abbreviation) even though the flight is operated by another airline. However, codeshare relationships can affect whether an interline ticket (or e-ticket) can be issued. Both the codeshare marketing carrier and codeshare operating carrier must have interline agreements with all other carriers in the itinerary to allow a single ticket to be issued.

Interline agreements are directional. For example it may be possible for American Airlines to issue the ticket on an American-United itinerary but United might not be able to be issuer on the same itinerary.

Airlines that have been established for many years are sometimes called "legacy", "network", or "full-service airlines." Previously, only large network carriers such as United Airlines and Lufthansa would have electronic ticket interline agreements but the IATA mandate to eliminate paper tickets at the end of 2007 has changed this by forcing smaller carriers to implement electronic ticketing. For example, United Airlines has an interline ticketing agreement with competitors American Airlines and British Airways. Smaller legacy carriers commonly have interline agreements with large network carriers that fly into their markets. Most newer low-cost carrier airlines that only sell directly to consumers (and not through agencies or GDS systems) do not support interlining at all. For example, United Airlines does not have an interline agreement with Southwest Airlines or Easyjet.

If no interline ticketing agreement exists (such as with Southwest and United Airlines), then two separate tickets will need to be issued and passengers will have to retrieve their bags and carry it to the connecting airline for check-in. Itineraries with interline connections such as this (whether issued on a single ticket or two tickets) are risky for travelers since the second carrier may be unaware of delays or issues with the incoming flight and it is more likely for luggage to be lost.

Most online travel agencies will only display itineraries that can be ticketed on one of their booking systems. However Orbitz will sometimes display un-ticketable interline itineraries. Examples could be found previously on routes to Mexico involving the now defunct Aero California or may be currently found on routes to Indonesia involving Lion Air. These display on Orbitz as "contact airline to buy".