When the number of flights increases to a level that creates regular and significant flight delays, and infrastructure improvements to manage the capacity are not feasible in the near future, the airport may be declared a Level 3 airport by the FAA.

A Level 3 Airport is a classification defined by the International Air Transport Association (IATA) as a "Coordinated Airport" where the demand for flights significantly exceeds the available airport capacity (runway slots, terminal space, or gates). At these airports, such as London Heathrow, Dubai International, or New York JFK, it is mandatory for all airlines to obtain a specific landing or takeoff slot from an independent slot coordinator to operate. The coordination process is highly regulated to prevent extreme congestion and delays. If an airline fails to use their allocated slots for at least 80% of the time, they risk losing them—a rule that sometimes leads to controversial "ghost flights" to maintain rights. As of 2026, there are nearly 200 Level 3 airports globally, representing the most congested hubs where infrastructure limits require strict scheduling to ensure safety and operational efficiency.