The Federal Aviation Administration (FAA) uses runway slots to limit scheduled air traffic at certain capacity constrained airports. In the U.S., those airports are John F. Kennedy International Airport (JFK), LaGuardia Airport (LGA), and Ronald Reagan Washington National Airport (DCA). In addition, the FAA monitors scheduled air traffic demand at other airports and has a formal schedule review and approval process at several airports. Those airports are Chicago O’Hare International Airport (ORD), Los Angeles International Airport (LAX), Newark Liberty International Airport (EWR), and San Francisco International Airport (SFO).
At EWR, JFK, LAX, ORD, and SFO, the FAA generally follows the International Air Transport Association (IATA) Worldwide Slot Guides (WSG) to the extent they do not conflict with U.S. laws, rules, or procedures. WSG is a set of standards and best practices developed by IATA Member airlines along with the airport coordinator and facilitator communities.