WASHINGTON (Reuters) -Aeromexico on Friday asked the 11th Circuit Court of Appeals to halt a Trump administration order forcing it to unwind a joint venture with Delta Air Lines ( DAL ) by January 1 that lets the carriers coordinate scheduling, pricing and capacity decisions for U.S.-Mexico flights.

Aeromexico said it would face substantial costs to unwind the joint venture that it could not recover even if a court later upheld the arrangement. The U.S. Transportation Department in September ordered an end to the nearly nine-year-old joint venture as part of a number of actions aimed at Mexican aviation, citing competition concerns.