A service established with the objective of contributing to a safe, orderly and expeditious flow of air traffic by ensuring that ATC capacity is utilized to the maximum extent possible, and that the traffic volume is compatible with the capacities declared by the appropriate ATS authority.
Source: ICAO Doc 4444 PANS-ATM
Description
The objective of ATFM is to ensure optimal traffic flow when demand is expected to exceed the available capacity of the ATC system. It comprises activities related to traffic organization and handling in a way that is safe, orderly, expeditious and kept within the capacity. ATC capacity reflects the ability of the system to provide service, and is expressed in numbers of aircraft entering a specified portion of the airspace in a given period of time.