United CEO Says Premium Push Runs Up Against Planemaker Woes (1)

United Airlines Holdings Inc. Chief Executive Officer Scott Kirby says a lack of new aircraft is impeding his plans to modernize the fleet and cash in on booming premium travel.

Engine shortages and supply-chain snarls have slowed deliveries from Airbus SE, while Boeing Co. struggles with certification delays and production curbs on models like the 777X and 737 Max 10 jet, which United had ordered in large numbers.

As a result, the biggest US airline is flying out-of-production aircraft, including Boeing’s 757 and 767, on lucrative long-haul routes — a major setback for United, which has invested heavily in ...