A Ground Delay Program (GDP) is a traffic management procedure
where aircraft are delayed at their departure airport in order to
manage demand and capacity at their arrival airport. Flights are
assigned departure times, which in turn regulates their arrival time
at the impacted airport.
GDP will normally be implemented at airports where capacity has
been reduced because of weather—such as low ceilings, thunderstorms
or wind—or when demand exceeds capacity for a sustained period.
GDPs are implemented to ensure the arrival demand at an airport
is kept at a manageable level to preclude extensive holding and to
prevent aircraft from having to divert to other airports. They are
also used in support of Severe Weather Avoidance Plan (SWAP).
(See section on SWAP.)