United Airlines said it will permanently exit New York’s John F. Kennedy International Airport (JFK) by the end of October, unless the FAA offers up additional slot pairs at the crowded airport.

United’s current JFK service consists of just four daily flights; two transcon routes per day to both Los Angeles (LAX) and San Francisco (SFO), according to a spokeswoman, with the bulk of the airline's New York services operating from its hub at Newark (EWR).

The company was able to obtain some additional slots on an interim basis from other carriers after resuming service in February 2021 but has since returned those slots as demand surged back to pre-crisis levels.

Since resuming JFK service, the Chicago-based carrier has made “repeated requests” to the FAA for additional permanent slots, while also pursuing commercial agreements to acquire slots from other airlines, but its efforts have all been unsuccessful, CEO Scott Kirby wrote in a Sept. 6 letter to employees.

Now, the airline is making a last-ditch effort to secure an interim multi-season slot allocation from the FAA, outlined in a separate letter sent by Kirby to Acting FAA Administrator Billy Nolen last week

If that request is granted, Kirby said United is “prepared to expand” its service at JFK. But if the carrier cannot secure additional allocations for multiple seasons, it will need to suspend service at the airport by the end of October, he warned.

“That would obviously be a tough and frustrating step to take and one that we have worked really hard to prevent,” Kirby wrote.

JFK has four total runways—consisting of two pairs of parallel runways—with the ability to shift between two arrival or two departure runways to accommodate demand spikes, compared to three runways at EWR, Kirby noted. But despite having an extra runway, JFK’s capacity has remained capped at 81 runway movements per hour since 2008, just two more movements than EWR’s maximum of 79 per hour, Kirby noted.

The FAA said in a statement that it “continually looks for ways to increase the efficiency of airspace in busy metropolitan areas safely,” and that any additional slot pairs at JFK must be “distributed fairly.” The agency also said it must “consider airspace capacity and runway capacity to assess how changes would affect flights at nearby airports” when making decisions about JFK’s capacity caps.