United Airlines (NASDAQ: UAL) announced plans to add more than 250 new aircraft to its fleet by April 2028, which the company claims will be the most aircraft added by any airline in a two-year period.

The expansion includes several new aircraft variants and cabin configurations. The airline will introduce 40 Airbus A321neo "Coastliner" aircraft featuring a special livery and configured with lie-flat business class seats for transcontinental routes between Los Angeles, San Francisco and Newark. These flights will offer domestic travelers access to United Polaris lounges for the first time.

United will also deploy 28 Airbus A321XLR aircraft with 32 premium seats to replace Boeing 757s on existing European and South American routes. The A321XLR will begin service this summer.

The carrier plans to introduce the CRJ450, operated by SkyWest, connecting smaller cities to Denver and Chicago hubs starting this fall. The 41-seat regional aircraft features a luggage closet instead of overhead bins in the first-class cabin.

United's new Boeing 787-9 aircraft with upgraded interiors will begin international service on April 22, flying from San Francisco to Singapore. These planes include United Polaris Studio suites that are 25% larger than standard business class seats and feature 27-inch screens.

The fleet additions include 47 Boeing 787-9 Dreamliners, 119 Boeing 737 MAX aircraft, and 18 additional Airbus A321neos. Since 2021, United has added 326 new aircraft including 22 Boeing 787s, 237 Boeing 737 MAX, and 67 Airbus A321neos.

The airline reports it has completed 70% of its mainline narrow-body fleet retrofit plan, replaced more than 100 regional jets with larger aircraft, increased premium seats per North American departure by 40%, and hired more than 60,000 employees since 2021.

"For more than a decade, we've invested billions of dollars in our product, service, and technology as part of our plan to be the best brand loyal airline in the world," said CEO Scott Kirby in the company's announcement.