The FAA hasn’t put a timeline on when it will ease back on the flight limitations. Transportation Secretary Sean Duffy says the cuts won’t go away until safety measurements improve and staffing levels stabilize at air traffic control facilities. And the cuts will jump to 10% on Friday.

Duffy has declined to share the specific data that prompted FAA to imposed the flight cuts last week. But at a news conference Tuesday at Chicago's O'Hare airport, he said he was seeing reports of loss of separation between planes in the air, more runway incursions and airline pilots telling the FAA they were concerned with the responses they were getting from controllers.

The nationwide shortage of air traffic controllers isn’t new, but the shutdown exposed just how fragile the system is. Controllers who weren’t being paid have increasingly called off work during the shutdown, citing increased stress and the need to take side jobs to pay bills. Union leaders said this week that the number of controllers who retired or quit during the shutdown was “growing” by the day.