United Airlines has received an FAA waiver allowing it to remove around 50 departures a day from Newark (EWR) in New Jersey beginning next month in an effort to reduce congestion and improve its on-time performance.

The frequency reductions at the United hub come in response to several weeks of irregular operations at EWR, which prompted United to request a waiver from the FAA allowing it to temporarily adjust its schedule there for the remainder of the summer. The 50 daily departures being removed amount to about 12% of United’s roughly 425 total daily flights at the airport.

The schedule changes will go into effect July 1. The removed flights are all domestic routes and will not result in any market exits, just frequency reductions. The company said it is “proactively reaching out” to customers affected by the moves to accommodate them on alternate flights.

A United spokesperson said that the flight cuts are being made in response to capacity constraints, including airport construction and air traffic control staffing shortfalls, but not airline staffing issues. The company does not expect schedule changes at its other six domestic hubs, and hopes to reinstate the 50 canceled departures “as soon as possible.”

United has long been concerned about congestion at Newark, where the FAA restricts runways to a maximum of 79 operations per hour spread across all airlines. United executives, including Chief Operating Officer Jon Roitman and CEO Scott Kirby, have previously expressed concern that those limitations are being exceeded on many days, and have called on the FAA to intervene to remedy the situation.

Roitman in April sent a staff memo blaming the “continued unreliability” of JetBlue Airways and Spirit Airlines–both of which suffered from repeated operational meltdowns in recent months–for “exacerbating an already difficult situation” at EWR. JetBlue Senior Vice President-Government Affairs Robert Land said in response in a letter to the US Transportation Department that United–which controls 70% of departures at EWR–should “look in the proverbial mirror” when blaming other carriers for operational issues at the airport.

United’s flight cuts come as other US carriers are trimming their schedules in response to staffing shortages and higher fuel prices. The moves have prompted scrutiny from Transportation Department Secretary Pete Buttigieg, who held a meeting with major airline CEOs last week to discuss ways to fortify their operations ahead of the busy July 4 holiday travel period.

But while Buttigieg has threatened to use enforcement actions to get airline operations under control, he will be limited in his ability to improve the situation, cautions Bob Mann of consultancy R.W. Mann & Co., who largely blames poor airline crew scheduling practices for the spike in irregular operations.

“If [the Transportation Department] was going to call airline CEOs on the carpet, that should have been done in March 2022 for this summer, and realistically, starting years ago, and done regularly,” Mann told the Aviation Week Network. “This is a decades-long running problem that airlines have been reluctant to deal with—and it is overwhelmingly an airline problem to solve, not the FAA.”