By: Joel Thayer, Thayer PLLC

Chicago O’Hare is one of the last remaining dual-hub airports in the U.S. where two major carriers (United and American) compete head-to-head. That competition is what delivers lower fares, more routes, and better service to travelers.

This equilibrium is now under threat.

United Airlines has been aggressively expanding flights at O’Hare adding hundreds of additional daily flights. This is far outpacing actual demand growth and exceeding what its competitors are doing. This isn’t organic growth, it’s a strategy.

What’s the strategy? Because under O’Hare’s gate-allocation rules, gates are awarded based on prior flight activity, which means more United flights today translates to more gates for United tomorrow, and, ultimately, a long-term control over the airport. That’s a perverse incentive that rewards volume, not service. Industry observers call this “flooding the zone.”

By saturating the schedule, including with lightly-trafficked, duplicative routes, United is building a structural moat designed to crowd out American and tilt O’Hare toward a single-carrier hub.

The fallout is already visible: Congestion is worsening, delays are mounting where the FAA had to step in with flight caps to prevent system breakdown. This is a scheduling arms race that O’Hare’s runways, terminals, and ATC simply cannot absorb.

The stakes for consumers are enormous. United already has the highest-priced flights in 38 states. At airports where it runs a “fortress hub,” it commands roughly 70% regional market share. Dulles and SFO, both single-carrier hubs, post the two highest average fares in the country.

This isn’t just a business dispute. It has the hallmarks of a Sherman Act §2 attempted-monopolization claim. Gates at O’Hare are a textbook bottleneck, and United CEO Scott Kirby reportedly told investors the goal is to prevent American from “winning a single gate” at United’s expense. That’s not competition on the merits, it’s foreclosure.

The Bork consumer-welfare standard says antitrust protects competition, not competitors. But when fares rise, choices narrow, and reliability collapses after consolidation — every dimension of consumer welfare loses. Price is one input and quality is the other. Both are at risk.

Unfortunately, it gets worse. There are reports United wants to merge with American. Let’s start with the obvious, a merger between the second and third largest airline carriers in the United States would face significant legal obstacles. Courts would likely consider such a consolidation to be presumptively illegal under antitrust laws, especially when considering the Spirit’s attempt to merge with JetBlue in the Biden era. This is especially true now that Spirit has closed shop for good. Even President Trump has signaled opposition.

Trump’s FAA is acting with imposing flight caps. Because United added the most flights, it bears the largest reductions, which resulted in about 200 to American’s 40. That’s proportional and fair. Even former FAA Administrator under President Obama applauded the FAA’s action.

But caps treat the symptom. The real disease is the gate-allocation rule itself. We need regulatory reforms, that could include decoupling gate allocations from raw flight counts, or prioritizing efficiency and passenger throughput, or guaranteeing meaningful access for competing carriers.

The lesson goes beyond Chicago. Without structural fixes, the overscheduling cycle will repeat at O’Hare and elsewhere. Competition depends on rules and bad incentives produce bad outcomes, even when each individual move is “lawful.” Congestion can be a competitive weapon, not just an operational headache.

O’Hare is at an inflection point. We can preserve fair access, rational incentives, and operational discipline, or we can let one of America’s most competitive airports become a fortress hub with higher fares, fewer choices, and more delays.

Travelers will pay either way. At its core, the O’Hare dispute is about affordability: who pays, and why.

Joel Thayer is an attorney based in Washington, D.C. who focuses on antitrust law and consumer protection. He previously served as a congressional staffer for two republican offices and a law clerk for Federal Communications Commissioner Chairman Ajit Pai and Federal Trade Commission Commissioner Maureen Ohlhausen.