Aviation regulators are poised to start revoking unused slots for international flights at congested US airports, reversing a policy established early on in the Covid-19 pandemic.

The Federal Aviation Administration said in a decision posted Friday that it denied a petition by trade groups Airlines for America and the International Air Transport Association which sought to extend waivers allowing carriers to maintain their slots while many international routes were halted. The waivers expire on Saturday. 

The government’s policy is “to encourage high utilization of scarce public infrastructure,” the FAA said in the decision, which was posted on the Federal Register. The agency acknowledged that some countries, such as China, were still restricting flights, but said it would use more “targeted relief” in those instances. 

The action comes as demand for flights has soared this year, bouncing back from the steep declines starting in 2020. The industry continues to face challenges with staffing and other issues as it tries to ramp back to pre-pandemic levels. 

The FAA will generally require that carriers use 80% of each international slot at the most congested airports: Ronald Reagan Washington National, John F. Kennedy, LaGuardia, Chicago O’Hare, Los Angeles, Newark Liberty, and San Francisco.