FAA Ground Stops vs. Ground Delays: Understanding Air Traffic Control Measures

The US Federal Aviation Administration (FAA) utilizes two primary air traffic flow management tools—Ground Delay Programs (GDPs) and Ground Stops (GSs)—to mitigate congestion and ensure safety during periods when airport capacity is compromised. GDPs are implemented when the projected air traffic demand is expected to exceed an airport's acceptance rate for an extended duration, typically due to adverse weather conditions such as snow, high winds, or low visibility caused by fog or low cloud cover. When a GDP is active, flights destined for the affected airport are held at their departure point and assigned a controlled departure time, effectively metering the arrival flow to prevent excessive airborne holding or ground congestion.

In contrast, a Ground Stop is a more severe, though usually shorter, measure that completely halts all arriving traffic at the affected airport. GSs are often triggered by immediate threats, such as severe thunderstorms or critical runway obstructions. While GDPs manage volume over a period, GSs provide an immediate cessation of traffic movement. The FAA issues specific alerts for both programs, detailing the affected airport (via its three-letter code), the reason (e.g., wind), and the expected duration or average delay time, often using Zulu (universal) time for standardization across time zones. Airlines then utilize this FAA data, available on the National Airspace System Status page, to determine whether individual flights should be canceled or further delayed.