With a slew of air-traffic controller furloughs set to kick in on Sunday, the Federal Aviation Administration has given the airline industry the heads-up that these staffing shortages could affect upwards of 7,000 flights every day at the nation’s busiest airports.

According to the Wall Street Journal, the head of operations for the FAA’s Air Traffic Organization met earlier this week with executives from the major airlines to explain the impact of these furloughs, which require FAA employees to take off one day per 10 work days.

Though these furloughs will be applied uniformly around the nation, they will have the most impact at the nation’s busiest airports.

The lack of manpower at air-traffic control sites means the FAA will need to enact a ground-delay program at seven major airports, including Chicago’s O’Hare, all three major New York City area airports and Los Angeles International. This means that flights will be held at their originating airport until controllers are certain there will be space for the plan to land at one of these destinations.

The FAA estimates that the impact of the furloughs will vary depending on the airport. For example, the hourly arrival rate at Newark International will drop by 21%, while LAX will see a drop in arrivals/hour at 40%, nearly double Newark’s rate.

Additionally, a handful of other airports — including Atlanta’s Hartsfield, Philadelphia International, Miami, and San Francisco — will likely require daily traffic management for thousands of flights, which means travel in and out of these hubs will be slowed to maintain a more manageable pace.

“We’re not going to move as many airplanes as we normally could if we had the bodies and positions that we need,” the president of the local National Air Traffic Controllers Association at Newark tells Bloomberg about the furloughs’ impact. “You’re going into the busiest season in the most complex airspace in the country with less controllers.”

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