Southwest, LOT Polish Launch Interline Partnership

DALLAS — Southwest Airlines (WN) and LOT Polish Airlines (LO) launched an interline partnership on September 1, 2026, allowing travelers to book a single itinerary that combines flights operated by the two carriers.

Bookings are available through LOT, travel agents and third-party travel websites. The airlines connect through Los Angeles International Airport (LAX), Miami International Airport (MIA) and San Francisco International Airport (SFO), according to Southwest's airline-partner page.

LOT operates long-haul flights from those gateways to Warsaw Chopin Airport (WAW), where passengers can connect across the carrier's Central and Eastern European network and to LOT destinations in India, Japan and South Korea. The Polish carrier uses Boeing 787 Dreamliner aircraft on its long-haul network.

Southwest Chief Commercial Officer Justin Jones said the arrangement opens more U.S. destinations to LOT passengers while giving Southwest customers access to additional markets in Central and Eastern Europe. Southwest identified LOT as its 11th named airline partner.

How the Interline Agreement Works

The agreement allows the two airlines' independently operated flights to be sold on one ticket. LOT's guidance for interline passengers says travelers check in with the airline operating the first segment and that checked baggage can be tagged to the final destination under the itinerary's baggage and fare conditions.

Passengers arriving from abroad and connecting within the United States generally must collect their bags for customs and recheck them at the first U.S. port of entry. U.S. Customs and Border Protection says this requirement applies even when baggage is tagged to the final destination, although precleared flights and limited remote-screening arrangements may follow different procedures.

The arrangement is not an announced codeshare. Southwest and LOT did not say that either airline would place its marketing code on flights operated by the other.

The September 1, 2026, announcement lists LOT, travel agents and travel websites as the available sales channels. It does not list Southwest.com or describe loyalty benefits involving LOT-operated flights.

Southwest Builds Its International Partner Network

Southwest began interline operations with its first airline partner, Icelandair, in February 2025. Its partner portfolio has since grown across transatlantic and transpacific markets, with the partner airlines operating the long-haul segments beyond Southwest's network.

The LOT agreement follows other interline launches, including the Southwest-Philippine Airlines partnership that began in November 2025.

Among the three partnership gateways, San Francisco is LOT's newest U.S. destination. The airline opened Warsaw–San Francisco service on May 6, 2026, with four weekly flights scheduled through October 22, 2026, for the summer season. Los Angeles and Miami were already part of LOT's U.S. long-haul network.

Southwest's September 1, 2026, announcement did not include new routes or additional flights. The immediate change is commercial: LOT can sell more U.S. destinations behind the three gateways on the same itinerary, while the arrangement can send connecting passengers from LOT's transatlantic network onto Southwest flights.