Definition
A traffic management initiative used by the FAA's Air Traffic Control System Command Center to manage demand through a defined volume of airspace where capacity is reduced, typically due to severe weather. Flights filed to operate through the affected airspace are assigned an Expect Departure Clearance Time (EDCT) that delays departure so that arrivals into the constrained airspace match its available capacity.
Plain English
When bad weather or another problem cuts the amount of traffic a chunk of airspace can handle, the FAA holds some flights on the ground and gives them a specific later takeoff time so the airspace doesn't get overloaded.
Context Anchor
Pilots may see an AFP in flight planning, dispatch releases, traffic management notices, or departure delay information when a route passes through constrained airspace.
Derivation
"Airspace" identifies the area being managed, and "Flow" refers to flow control — regulating the rate at which aircraft enter a constrained area, much like metering cars onto a busy highway.
Why Pilots Care
Pilots may receive a departure delay or an alternate route when an AFP is active on their intended path, directly affecting schedule and fuel planning.
Intuition Check
Do not think of an AFP as only an airport delay. An AFP manages traffic through a defined area of airspace, even if the destination airport itself is not the main problem.
Example Sentence 1
Dispatch advised that an AFP was active over the northeast corridor, and our flight received an EDCT pushing departure back forty-five minutes.
Example Sentence 2
Because of the AFP, the crew accepted a reroute that added 20 minutes but avoided the constrained sector.