Definition
A traffic management initiative used by Air Traffic Control to manage the flow of aircraft into a destination airport when arrival demand is expected to exceed the airport's capacity. Affected flights are held on the ground at their departure airports and assigned a controlled departure time, so that arrivals at the constrained airport are spaced out and do not overwhelm it.
Plain English
When too many planes are heading to the same airport at the same time — usually because of bad weather or runway issues — controllers keep some of them on the ground at their starting airports and give them a later takeoff time. This spreads arrivals out so the destination can handle them safely.
Context Anchor
Pilots may see GDP information during flight planning, before departure, or when air traffic control assigns a later departure time for a flight going to a busy or weather-affected airport.
Why Pilots Care
It prevents excessive airborne holding, reduces fuel burn, and maintains safer spacing in the arrival flow.
Analogy
It is like holding cars at the entrance to a crowded parking lot instead of letting all of them rush in and block the lanes inside.
Intuition Check
Do not read GDP as just any delay that happens while an airplane is on the ground. In this context, it means a formal air traffic control program that assigns departure delays to manage arrival traffic safely.
Example Sentence 1
Dispatch advised the crew that a GDP was in effect for Newark due to low ceilings, pushing their wheels-up time back by forty minutes.
Example Sentence 2
The pilot checked the current GDPs before filing to avoid an unexpected ground hold.