Definition

Capacity. The maximum number of aircraft that can be accommodated in a given time period by the system or one of its components (throughput).

Source: ICAO Doc 9882 - Manual on Air Traffic Management System Requirements

Description

The capacity of an ATS system depends on many factors, including route structure, aircraft using the airspace, weather, available equipment and prevailing procedures. There is a natural drive to extend capacity so that fewer restrictions are applied to aircraft. However, an increse in capacity should not result in reduced safety levels - the number of aircraft being provided with ATC service should not exceed that which can be safely handled. The maximum number of flights which can be safely accommodated is assessed using an appropriate method and then declared to the parties concerned. This is done for control areas (as well as the sectors within) and for aerodromes.

ATC capacity is the maximum number of aircraft which can be accepted over a given period of time within the airspace or at the aerodrome concerned. This can be expressed by e.g.: