What is an interline agreement?

An agreement between airlines to carry each other's passengers and bags on one ticket, even outside an alliance.

Interline agreement, explained

When two airlines interline, a single ticket can combine their flights, and bags can be checked through to the final destination. If one flight is delayed, the airlines rebook the connection.

Without an agreement, the trip needs separate tickets, and a missed connection between them is the traveler's risk.

Interline agreements are separate from alliances and codeshares: an airline can interline with dozens of airlines outside its alliance. For a business class trip that ends on a smaller airline beyond a hub, the agreement is the difference between one protected itinerary, with one set of fare rules, and two separate bookings.

On a business class trip

A trip on Emirates to Dubai and onward on a partner airline can be one ticket when the two airlines interline.

Related terms

Codeshare flight
A flight sold under the flight number of more than one airline. One airline flies the plane; the others sell seats on it.
Airline alliance
A group of airlines that share networks, lounges and loyalty benefits: Star Alliance, oneworld and SkyTeam.
Multi-city ticket
One ticket with three or more flights between different cities, priced and issued together rather than as separate tickets.

Every term in the glossary.