American Airlines has filed suit against the city of Chicago, alleging the city is violating a lease agreement by moving forward with a reallocation of gate space at O’Hare International Airport. The lawsuit claims the city's action is premature and unfairly favors competitor United Airlines.

The legal action, filed Friday, centers on the city’s plan to conduct a gate redetermination this year. American contends this move breaches the terms of the 2018 Airline Use and Lease Agreement (AULA), which included provisions for a "Gate Space Ramp-up Period" intended to follow significant construction projects.

American argues this ramp-up period, designed to allow airlines to utilize newly completed gates for at least one year before a redetermination, has not concluded. Specifically, the airline points to the recent operational status of three new gates in Terminal 3 as a trigger for this period, which should prohibit reshuffling until at least April 2027.

The proposed gate shift, according to American, would result in United Airlines gaining five gates while American Airlines loses four. United currently holds 88 gates at O'Hare, compared to American's 71, making them the two largest carriers at the airport.

American alleges the Chicago Department of Aviation (CDA) is proceeding with the reallocation "at United’s request," depriving American of the opportunity to grow its operations based on passenger demand before gates are reallocated according to flight statistics from 2024.

Court documents detail American's claim of a "backroom deal" between United and the city, alleging city officials made false statements during the 2018 AULA negotiations regarding agreements with third parties like United. United's stated desire to increase its presence and potentially take over gates currently used by American was noted in the suit.

United Airlines deferred comment on the lawsuit to the city. A spokesperson for Chicago’s Law Department stated Monday the city had not been formally served with the complaint and does not comment on pending litigation.

The feud over gate allocation at O'Hare continues despite American adding routes and frequencies from the airport in recent months.

American maintains its presence fosters competition at O'Hare.

"American is committed to keeping O’Hare competitive, as our presence yields more extensive flight schedules and lower fares for our Chicagoland customers and travelers from across the world,” American Airlines said in a statement.

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