The news: American Airlines and Alaska Air are deepening their partnership as competition for higher-spending travelers heats up among the biggest US carriers.

Alaska plans to join American’s Atlantic and Pacific joint businesses, arrangements that let carriers coordinate schedules, align pricing, and share revenues on select international routes. The carriers plan to seek antitrust immunity with the Department of Transportation to avoid running afoul of US antitrust laws.

The tie-up could help each airline better compete with Delta and United, which have invested heavily in premium upgrades that have bolstered sales.

The bigger picture: Airlines are battling for higher-spending travelers across nearly every part of the customer experience—from premium seats and lounges to international networks, loyalty programs, and inflight connectivity.

American is trying to narrow its gap with Delta and United. In August, it announced plans to put seatback screens on more than 800 narrow-body planes, reversing an earlier strategy of removing them, while increasing the share of premium seats on narrow-body departures to 40% from about 25%. The carrier is also bringing Starlink Wi-Fi to hundreds of planes.

Alaska is taking on similar upgrades, targeting travelers with the ability to absorb higher fares as it expands beyond its traditional West Coast network. Aurora Suites, which will include lie-flat seats with privacy doors, will lift premium seating on Alaska's 787-9 fleet to about 46%, up from 38%.

Those improvements could be crucial as United sets out to poach its rivals' most valuable customers. The carrier launched a status-match campaign targeting elite members of American and Delta's loyalty programs, offering comparable United status for 90 days and using its Starlink Wi-Fi rollout as another incentive to switch.

The opportunity for American and Alaska: Winning premium travelers takes more than better seats. Airlines also need the network breadth to keep customers. That’s where the joint business venture could help. American gets a deeper relationship with a growing West Coast carrier, while Alaska gains access to a much broader international network without having to build that capacity itself. Alaska said joining the businesses is "critical" to developing its international reach and would put the carrier on "equal footing with its competitors."

Implications for airlines: The fight for premium travelers is becoming a fight over the entire airline ecosystem.

Delta’s and United's success with premium and international travelers is leading competitors to respond on multiple fronts. American is upgrading its domestic product while strengthening partnerships, and Alaska is using its Hawaiian acquisition to transform itself into a more global carrier while adding premium upgrades.

Rather than replicate every part of Delta's or United's global networks independently, American and Alaska can combine more of their respective strengths and scale their business. But antitrust immunity isn't guaranteed, and regulators have taken years to rule on similar arrangements.

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