United Airlines is ordering 110 additional Boeing and Airbus jetliners, locking in a supply of new planes into the next decade as strong demand and supply chain challenges make new delivery slots scarce.

“We would not normally order jets this far out,” United’s chief commercial officer, Andrew Nocella, told reporters Tuesday. “Production lines, which are now regularly plagued by supply-chain disruptions and delivery delays, are also increasingly sold out for the entire decade.” Deliveries of the new planes are scheduled to start in 2028.

United’s order consists of 50 more Boeing 787 Dreamliners, adding to a firm order of 100 of the twin-aisle planes it announced last December, along with 50 more options. The airline has aggressively expanded its international service to try to capitalize on a resurgence of trips abroad, destinations that the new long-range 787 planes would serve.

The Chicago-based airline is also buying 60 Airbus A321neos, on top of the 120 it previously had on order with the European manufacturer, including 50 of forthcoming extra-long-range version. United added options for 40 more Airbus A321s.

United and other airlines have recently ordered new planes have said one way around infrastructure constraints is to operate larger aircraft with more seats on them, a practice known as upgauging. The airline said it expects an average of more than 145 seats per North American departure in 2027, up 40% from 2019.

The carrier’s upsized order comes as airlines are battling for new, more fuel-efficient aircraft to cater to the post-Covid travel boom. Delivery delays have left airlines with a shortfall of planes, while upgrades that target an increasing number of travelers willing to splurge on premium seats have also run behind schedule.

United on Tuesday announced a revamp of its bedding and amenities kits for its Polaris business class, which include eye serums and a face spray.