At the 29th Annual Conference SC 1 was tasked with the monitoring of developments in ATFM. SC 1 has presented at the 30th Annual conference WP No. 54 in which a world-wide overview was given on developments in ATFM. At the same conference the ICAO representative presented two papers on ATFM, e.g. flimsies 4 & 5 . During the discussion in committee B on flimsy 4, concerning techniques for ATC sector/position capacity estimation, SC 1 was asked to consider the methods to assess ATC sector capacity.

At the 31st Annual Conference SC 1 presented WP No 76. In this WP SC 1 reviewed sector capacity measurement methods and committee B accepted two additions to the existing policy on ATFM:

a) Capacity values should be established for all sectors;

b) Operational controllers should always be involved in determining capacity values.

After discussion in committee B on this subject it was decided that SC 1 should investigate a common set of factors to be used in capacity measurement methods.

When considering the task as it was put on the work programme by the Annual Conference, SC1 had decided to approach it from two sides:

1. by studying the available studies on capacity measurement methods in order to extract the factors used in these methods and;
2. by producing a list of factors which, from a controllers point of view, should be considered when assessing ATC capacity, by comparing the two lists it then would be possible to determine what the optimum set of factors to consider should be.

Unfortunately and for various reasons, SC 1 has not been able to get hold of the latest material concerning studies on capacity measurement methods. As SC 1 feels that only the latest and/or updated material should be used, the original developed approach could not be carried out.

As the CFMU (Central Flow Management Unit) development in Europe continues, States are required to give capacity value to the CFMU to enable the DBE (Data Bank Eurocontrol) to issue warnings indicating a potential excess of demand over capacity. As stated in earlier papers on this subject, there is no common method available to assess capacity values, and often are based on experience.

As it is IFATCA policy that “ Operational controllers should always be involved in determining capacity values”, SC1 has composed a list of factors which should be taken into account when capacity values are assessed. This is in order to provide guidance to MA’s. These factors are:

• Airspace structure;
• Airspace procedures;
• Airport layout;
• Available equipment and technology (communication, navigation and surveillance);
• Availability of back-up systems and procedures;
• Traffic mix and flight profiles;
• Available staff (number, level of training, working conditions);
• Human performance;
• Environmental issues like noise abatement procedures;
• Weather conditions;
• Buffers for non-plannable traffic and/or unusual events.

All these factors together will influence the workload of air traffic controllers in their respective areas of responsibility (Aerodrome, Terminal or En-route) and should lead to a capacity value for each individual ATC position. The capacity of the total ATC system will be determined by the weakest link in the whole chain.

From the material available on capacity measurement methods it can be concluded that these methods concentrate mainly on radar equipped area control sectors. For non-radar (equipped) ATC positions there is no method known to SC 1 to assess capacity and produce realistic capacity values.

To Conclude

In order to produce, from the controllers point of view, realistic capacity values MA’s should seek involvement to the assessment of ATC capacity. There are no common methods available for the assessment of ATC capacity for ATFM purposes. To assist MA’s when assessing ATC capacity, SC 1 has produced a set of factors which should be considered in the production of capacity values.

Attention should be given to methods to assess capacity for non-radar positions.