Alaska Airlines plans to join American Airlines’ Atlantic and Pacific Joint Businesses, expanding an existing relationship with American and their oneworld alliance partners. The arrangements would allow participating carriers to coordinate schedules, align pricing on selected routes and share revenue after regulatory approval. The airlines plan to file for antitrust immunity with the U.S. Department of Transportation and seek any required international approvals in the coming months. The Atlantic business, formed in 2010, includes American, British Airways, Iberia, Finnair, Aer Lingus and LEVEL; the Pacific business includes American and Japan Airlines. Alaska said the move would improve West Coast connectivity and international access. The announcement followed Alaska Air Group’s plans to add lie-flat suites, premium economy and lounges, as it targets at least 15 intercontinental destinations from Seattle by 2030, compared with seven currently.