US to reduce capacity by 10% at 40 airports: Transportation secretary

"There is going to be a 10% reduction in capacity at 40 of our locations," Duffy said at a news conference in Louisville, Kentucky.

“This is not based on what airline travel has more flights out of what location. This is about where is the pressure and how do we alleviate the pressure," he said.

Speaking along with Duffy, Federal Aviation Administration (FAA) Administrator Bryan Bedford said they have decided that a 10% reduction in scheduled capacity would be appropriate to take the pressure off of air traffic controllers.

"As we continue to see staffing triggers, there will be additional measures that will be taken in those specific markets," Duffy said.