Defying Heathrow’s management, Emirates said it won’t comply with a directive for airlines to cancel flights this summer to and from the London airport. Heathrow is trying to ease congestion at the airport.

“Emirates is a key and steadfast operator at LHR, having reinstated six daily A380 flights since October 2021,” the carrier said in a statement on Thursday. “From our past 10 months of regularly high seat loads, our operational requirements cannot be a surprise to the airport.”

On Tuesday, Heathrow CEO John Holland-Kaye wrote an open letter to flyers, explaining that it is capping the airport’s daily passenger capacity at 100,000 through Sept. 11. Kaye also asked airlines to stop selling summer tickets on flights to and from Heathrow, as daily bookings already exceed the cap.

Heathrow issued those orders while the airport attempts to address a rash of service problems this summer, including excessive security lines and widespread failures with baggage handling.

Emirates said Heathrow told the carrier on Wednesday evening that it must comply with capacity cuts within 36 hours. The airport, Emirates said, stated the specific flights on which the airlines should exclude passengers and threatened legal action for noncompliance.

Emirates asserts that Heathrow wants the carrier to deny seats to tens of thousands of passengers.

“Emirates believes in doing the right thing by our customers,” the airline said. “However, rebooking the sheer numbers of potentially impacted passengers is impossible with all flights running full for the next weeks, including at other London airports and on other airlines. Adding to the complexity, 70% of our customers from LHR are headed beyond Dubai to see loved ones in far-flung destinations, and it will be impossible to find them new onward connections at short notice.”

Heathrow didn’t immediately respond to a request for comment on Thursday afternoon.

Emirates said that until further notice, it plans to operate as scheduled from Heathrow.