Airline Alliances, Codeshares and Interline Agreements: What They Are and How They Work

What Are the Different Kinds of Cooperation Between Airlines?

Airlines can agree to cooperate with each other at many different levels. Generally, these forms of cooperation range between interline agreements, codeshare agreements and airline alliances. Let’s look at how each one of these works.

Interline Agreements

An interline agreement is the most basic level of cooperation between two airlines. Under this agreement, two airlines agree to handle passengers that are traveling on different airlines on the same itinerary. This enables travelers to get boarding passes and check their bags all the way through to their final destination. Airlines with interline agreements can even rebook passengers on the other airline if irregular operations occur. Since interline agreements are such a basic level commitment, airlines typically have interline agreements with dozens of other airlines even across different alliances. Expert Flyer is a great resource to check which airlines a given airline has interline agreements with.

Codeshare Agreements

As the name implies, a codeshare agreement is when two airlines place their codes on one another’s flights. For example, a Delta-operated flight from Atlanta to New York not only has a Delta flight number code (e.g., DL 1239), but also Air France (AF 858) or KLM (KL 742). One benefit for passengers is that they can have an entire itinerary with one airline’s code even when flying different carriers. Airlines with codeshare agreements strive to synchronize their schedules, which leads to more manageable connections usually, even when flying multiple carriers.

Airlines benefit from codeshare agreements because they get to market (and sell) a flight that they don’t operate. Let’s say you wanted to fly from Chicago to Hamburg, Germany. United does not fly to Hamburg, but it has a codeshare agreement with Lufthansa. So you can purchase directly from United a flight from Chicago to Hamburg, connecting in either Frankfurt or Munich. That connecting flight to Hamburg is operated by Lufthansa, but the codeshare agreement enables United to market that flight as a United airlines flight. Codeshare agreements are also a common part of airline alliances, but airlines still enter into codeshare agreements with non-alliance airlines.

Airline Alliances

Airline alliances are more involved than interline or codeshare agreements. Each airline member agrees to deliver reciprocal benefits to members across the alliance. One of the biggest benefit for travelers is reciprocity for elite status benefits, such as lounge access, priority check-in, and mileage earning and redemption. This last benefit of redeeming miles with different members is the biggest draw for award travelers.

How Do Airline Alliances Help Award Travelers?

Airline alliances are helpful for award travelers because they enable us to redeem miles from one airline for travel on another airline. For example, say you want to fly with Lufthansa to Europe. Lufthansa does not have any transfer partners among US banks. So how can you redeem points to fly Lufthansa? You can redeem miles from other Star Alliance programs, like Air Canada Aeroplan, United or Avianca LifeMiles. Here is an example of how you can use one airline’s miles to book award flights with partners airlines. This screenshot is from Air Canada’s website showing saver award availability on United and Lufthansa flights.

What About Other Partnerships?

Airlines can also strike interline or codeshare agreements with other airlines outside of their airline alliances. In fact, some major airlines don’t belong to any of the three global airline alliances at all! Emirates, Etihad, JetBlue, and Southwest aren’t members of Star Alliance, Oneworld or SkyTeam, yet they maintain individual partnerships with other airlines.

Outside Of The Big 3: Other Alliances

About a decade ago, a number of smaller airline alliances began to emerge. However, not all of them have survived. Vanilla Alliance was formed in 2015 with airlines from the Indian Ocean region, including Air Austral, Madagascar Airlines, Air Mauritius and Air Seychelles. But U-FLY Alliance and Value Alliance, which both formed in 2016 and focused on regional connectivity, are now inactive. Smaller alliances have largely faded away or become less relevant.