What Is a Ground Delay Program (GDP)?
A ground delay program is the FAA's way of preventing a traffic jam in the sky. When an airport can't handle its normal arrival rate — usually because of weather — the FAA assigns each inbound flight a specific departure time. Your flight still goes, just later.
How it works
- The FAA determines the airport's reduced arrival rate (AAR) — how many planes can land per hour given current conditions.
- Each inbound flight is assigned an EDCT (Expected Departure Clearance Time) — the exact minute it's cleared to depart.
- Airlines can swap slots between their own flights, prioritizing full planes or connecting passengers.
- When conditions improve, the GDP is lifted and normal operations resume.
Typical delays
Most GDP delays are 15 to 90 minutes. The FAA publishes the average delay for each active program. Unlike a ground stop, your flight will eventually depart — it's just held on the ground where fuel is cheaper and you have access to food and bathrooms.
What causes GDPs?
- Weather — low ceilings, thunderstorms, or fog reduce how many planes can land per hour.
- Wind shifts — when wind direction changes, the airport must switch runways, temporarily cutting capacity.
- Volume — more flights scheduled than the airport can handle, especially at hub airports during peak times.
- Runway/taxiway closures — construction or maintenance reducing available pavement.
GDP vs. ground stop
| Ground Delay Program | Ground Stop | |
|---|---|---|
| Flights depart? | Yes, with assigned delays | No — all held |
| Typical delay | 15–90 minutes | 1–4+ hours |
| Severity | Moderate | Severe |
| How common | Very common — most busy airports see GDPs weekly | Less common — major weather or emergencies |