Why Boeing and Airbus dominate the commercial jet industry

The big picture: For the last three decades, U.S.-based Boeing and Europe's Airbus have been the only game in town for large commercial jets.

• Single-aisle aircraft, or so-called narrow bodies, are the biggest segment of the commercial market.
• Airlines like United essentially have two options: Boeing's 737 lineup and Airbus' equivalent family of A320s. Those two made up nearly 70% of United's mainline aircraft fleet at the end of 2022.

What they're saying: "Well, I'll wait and see. Obviously, there's only one other manufacturer that's really an option for us," Kirby said yesterday on CNBC, when asked whether United could replace its delayed Boeing Max 10 orders with Airbus planes.

• "And it probably means that we don't grow quite as fast as we are hoping," he said, acknowledging how bottlenecks for new aircraft could prevent the carrier from meeting surging travel demand.

State of play: The Boeing and Airbus duopoly isn't likely to end soon, even as the former suffers a string of manufacturing issues.

• The industry has a high barrier of entry with enormous capital requirements. It's driven smaller manufacturers to focus on smaller regional jets and private aircraft.
• It's also heavily regulated, with Boeing's and Airbus' relationships with regulators described as a "historical partnership" built around safety.

What to watch: Brazil-based Embraer has been hoping to crack the U.S. market for its E2 jets. But if a third choice were to emerge, it could be Commercial Aircraft Corp of China.

• Both Boeing and Airbus have called the state-owned company a potential competitor. But Comac, as it's known, is unproven, and questions remain whether American or European carriers would buy Chinese planes in the current political environment.

The bottom line: Don't expect customers to give up on Boeing. Even Kirby yesterday called the company not just its most important partner, but "one of the most important companies in the country."