Southwest and China Airlines Adds New Interline Partnership

DALLAS- Southwest Airlines (WN) and China Airlines (CI) have announced a new interline partnership set to launch in early 2026.

The agreement will allow passengers to book seamless connections through major US West Coast airports like Los Angeles (LAX), San Francisco (SFO), Ontario (ONT), and Seattle (SEA).

This move marks Southwest’s second global partnership after Icelandair (FI) and its first trans-Pacific collaboration, potentially signaling a shift in the airline’s long-standing operational model.

Photo: By NgoQuocQuy – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=132474176

Southwest and China Airlines New Partnership

Southwest is gradually transitioning from a strictly domestic, low-cost carrier to a more globally connected airline.

The newly revealed interline partnership with China Airlines (CI) indicates the southwest’s ambition to expand international accessibility for its passengers without altering its core business drastically.

Under the agreement, China Airlines customers arriving at US West Coast hubs, Los Angeles (LAX), San Francisco (SFO), Ontario (ONT), and Seattle (SEA), will be able to connect seamlessly onto Southwest’s extensive domestic network.

These interline connections will be available for booking in late 2025, with flights commencing in early 2026.

According to OMAAT, while the partnership does not include codesharing or loyalty integration, it is still a notable development.

It’s especially significant given Southwest’s previously limited appetite for international partnerships and the minimal cooperation between China Airlines and SkyTeam member Delta Air Lines (DL), particularly at overlapping gateways.

Photo: Southwest Airlines

What is an Interline Agreement?

An interline agreement allows passengers to purchase a single itinerary that includes flights on both carriers.

For this partnership, it means a traveler flying from Taipei (TPE) to Los Angeles (LAX) on China Airlines could continue on a domestic leg to Las Vegas (LAS) or Denver (DEN) on Southwest using one booking and one checked bag process.

There will be no codeshare, meaning passengers will need to check in separately for each segment, and frequent flyer programs will remain unlinked.

However, this is still a pragmatic entry into international collaboration for Southwest, enabling better network reach with minimal operational disruption.

Photo: DJ.Cy | Flickr

Industry Context

This move is not expected to significantly alter the financial outcomes for either airline. However, it positions Southwest for more meaningful international collaborations in the future.

As global competition and customer expectations increase, such basic interline deals serve as test beds for deeper integration, including loyalty sharing and joint ventures.

It also reflects a broader industry trend where airlines forge low-commitment agreements to expand connectivity without full alliance memberships or equity stakes.

In markets like Ontario (ONT), where Delta’s presence is limited, Southwest’s dominant operations make it a particularly strategic partner for China Airlines.

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