<Ul> <Li> Icelandair: In 1997, Southwest and Icelandair entered into interline and marketing agreements allowing for joint fares, coordinated schedules, transfer of passenger luggage between the two airlines in Baltimore and a place connecting passengers between several U.S. cities and several European cities . The frequent flyer programs were not included in the agreement . This arrangement lasted for several years but ended when Icelandair's service from BWI to KEF ended in January 2007 . </Li> <Li> ATA Airlines: In a departure from its traditional "go it alone" strategy, Southwest entered into its first domestic codesharing arrangement with ATA, which enabled Southwest Airlines to serve ATA markets in Hawaii, Washington, D.C. and New York City . </Li> </Ul> <Li> Icelandair: In 1997, Southwest and Icelandair entered into interline and marketing agreements allowing for joint fares, coordinated schedules, transfer of passenger luggage between the two airlines in Baltimore and a place connecting passengers between several U.S. cities and several European cities . The frequent flyer programs were not included in the agreement . This arrangement lasted for several years but ended when Icelandair's service from BWI to KEF ended in January 2007 . </Li> <Li> ATA Airlines: In a departure from its traditional "go it alone" strategy, Southwest entered into its first domestic codesharing arrangement with ATA, which enabled Southwest Airlines to serve ATA markets in Hawaii, Washington, D.C. and New York City . </Li> <Dl> <Dd> At the time of ATA's demise in April 2008, the airline offered over 70 flights a week to Hawaii from Southwest's focus cities in PHX, LAS, LAX and OAK with connections available to many other cities across the United States . The ATA / Southwest codeshare was terminated when ATA filed for Chapter 11 bankruptcy on April 3, 2008 . Southwest ultimately acquired the operating certificate and some of the landing rights of ATA in the ensuing proceedings . </Dd> </Dl>

Which was the first airline to begin code-sharing agreements with southwest airlines