Southwest Airlines and Singapore Airlines Launch Interline Partnership

Southwest Airlines Co. and Singapore Airlines announced an interline partnership on June 8, 2026, enabling single-ticket travel across their respective networks through three shared United States gateway airports.

The agreement, detailed in a press release issued during the International Air Transport Association (IATA) Annual General Meeting in Rio de Janeiro, Brazil, marks Singapore Airlines as the eighth overseas carrier to join Southwest’s partnership portfolio. The arrangement connects Southwest’s domestic footprint with the SIA Group’s global reach, which encompasses more than 130 destinations across 35 countries and territories.

Network integration and gateway operations

The interline agreement facilitates passenger connections at Los Angeles (LAX), Seattle/Tacoma (SEA), and San Francisco (SFO). International travelers arriving on Singapore Airlines flights can transfer to nearly 120 airports within the Southwest network on a single booking, while U.S. travelers gain streamlined access to the SIA network.

Southwest Airlines Chief Operating Officer Andrew Watterson stated that the partnerships connects new geographies while maintaining high service standards for passengers transferring between the two carriers.

“Singapore Airlines becomes the eighth carrier in our partnership portfolio exemplified by its quality and reach. These carriers are facilitating access to our network for a growing global audience drawn to our improved onboard product and increasingly choosing to fly with us,” Watterson said.

Southwest’s 2026 product and route expansion

The partnership aligns with broader changes to the Southwest passenger experience implemented earlier in 2026. The carrier recently transitioned away from its traditional open-seating model, introducing assigned seating, optional extra legroom, and an updated boarding process designed to appeal to a wider demographic of travelers.

Alongside the cabin product updates, Southwest expanded its route map in 2026 by initiating service to five new destinations. The network additions include St. Thomas in the U.S. Virgin Islands, Sint Maarten, Santa Rosa/Sonoma County in California, Knoxville, Tennessee, and Anchorage, Alaska.

AirPro News analysis

We view this interline agreement as a strategic utilization of Southwest’s dense domestic network to capture international inbound traffic without the capital expenditure of operating long-haul widebody aircraft. By linking with a premium global carrier like Singapore Airlines at key West Coast hubs, Southwest can feed its domestic flights with high-yield international connecting passengers. The recent shift to assigned seating and premium legroom options likely makes Southwest a more palatable connecting partner for international travelers accustomed to traditional legacy carrier products, smoothing the passenger experience between a long-haul international flight and a domestic connection.

Sources: Southwest Airlines