Measures to increase ATC capacity. a) taking all reasonable steps to fully exploit the existing capacity of the air navigation system; b) developing plans to increase the capacity of the ATC system where required, particularly in the terminal airspace, so as to be able to meet the forecast traffic demand of the users. Such plans should take account of the need for effective SIDs and STARS, development of segregated VFR and IFR routes, assessment of impact of noise abatement procedures and curfew windows, development of procedures to accommodate emergency situations, etc.; negotiating letters of agreement between adjacent States to ensure the development of proper procedures for coordination and transfer of control. In this context, efforts should be made where possible and practicable to design sectorization independently of artificial boundaries, such as existing borders;

the need for effective SIDs and STARS, development of segregated VFR and IFR routes, assessment of impact of noise abatement procedures and curfew windows, development of procedures to accommodate emergency situations, etc.; (c) negotiating letters of agreement between adjacent States to ensure the development of proper procedures for coordination and transfer of control. In this context, efforts should be made where possible and practicable to design sectorization independently of artificial boundaries, such as existing borders; d) developing procedures between units to improve flow management to make maximum use of the available ATC capacity;

(e) ensuring that new measures to be adopted are introduced with minimum delay and preferably simultaneously by adjacent units; (f) designing ATC procedures for handling arriving aircraft in order to provide the best exploitation of available runways and landing capacity. This should be achieved in conjunction with the users’ requirements for optimum descent and direct path; and (g) achieving efficient arrival/departure operations through improved runway/taxiway design, such as the provision of parallel taxiways and high-speed runway exits.

A detailed traffic forecast regarding major traffic flows in a particular flight information region (FIR) or area composed of several FIRS should be prepared. Such forecasts should be used to determine the development of airspace and flow management as far ahead as possible and for a period of at least five years and in such a form that it can be used by all concerned with the planning of the air navigation system. They should indicate both average traffic demand and peak values, as well as seasonal, weekly or diurnal changes in future traffic demand. States should continuously review the capacity of their ATC system in order to ensure that it can be adjusted to accommodate forecast traffic demands.

CONTINGENCY PLANNING Status of contingency plans Contingency plans are intended to provide alternative facilities and services to those provided for in the regional air navigation plan when those facilities and services are temporarily not available. Contingency arrangements are therefore temporary in nature, remain in effect only until the services and facilities of the plan are re-activated and, accordingly, do not constitute amendments to the regional plan requiring processing in accordance with the “Procedure for the Amendment of Approved Regional Plans”. Responsibility for developing, promulgating and implementing contingency plans (a) the state responsible to provide ATS. (b) The state responsible to provide ATS over high seas. (c) The state responsible to provide ATS in the area of another state.

Techniques for ATC Sector/Position Capacity Estimation Knowledge of the capacity of air traffic control sectors or ATC operating positions is necessary for two reasons. Firstly, for long-term planning, adequate warning is required of any future shortfall in capacity, as indicated by traffic forecasts. Secondly, if there is already a shortage of capacity requiring the application of flow control, it is necessary to know what the capacity is, in order to limit air traffic to a level which does not overload the system or penalize the operator A considerable amount of work has been devoted in recent years to methods of estimating capacity. Of particular interest has been the work proposed by the United Kingdom, Directorate of Operation Research and Analysis (DORATASK Methodology for the assessment of ATC en-route sectors capacity - DORA Interim Report 8818; the application of this technique to current London Terminal Area Sectors.

Messerschmidt, BGlkow und Blohm (MBB) of Germany resulting in the development of a procedure to quantify the control capacity of ATC working positions, known as the “MBB Method”. DORATASK. The proposed DORATASK work centred on the assessment of the workload carried by the radar controller, summing the time spent on routine and conflict resolution (observable) tasks on the one hand, and planning (nonobservable)tasks on the other. In addition to these twointerrelated elements of the controller’s tasks, there was a third element - a “recuperation” time. This was a minimum proportion of time not allocated to specified tasks (observable or non-observable) but considered essential for the safe operation of the sector.

Observable tasks are those which can readily be recorded and timed by an outside observer; examples include radiotelephony (RTF) and telephone communication, strip marking and direct-voice-liaison coordination. Routine tasks, for a particular aircraft, are those which must be carried out even if there are no other aircraft in the vicinity.

Non-observable tasks are those which are carried out almost continuously by the busy controller in parallel with the observable tasks, and which cannot generally be directly recorded or timed by the observer. These tasks, which include monitoring the radar screen and planning future actions, are, however, critical to the business of the sector controller. The non-observable workload was determined by calculating, for each aircraft within the sector area, hqw many strips it produces and how many other strips already present on the boards must be checked against it when it is first given to the radar controller. This number of checks was then multiplied by a “time per strip check” to give the total non-observable workload. The time for a strip check was not considered as a duration time for a physical task but as a factor calculated when the model was calibrated to reflect the time taken by the whole planning task. The latter was the main aspect of DORATASK which required more detailed research. This kind of workload would be increased significantly during a peak flow of traffic.

The workload measure for a given sector and traffic sample was the sum of the observable and non-observable workload times. To arrive at capacity it was necessary to determine a minimum proportion of time that the controller must have for recuperation if the sector was to continue to be operated safely. This proportion was likely to increase with the length of time that a “capacity” flow rate was expected to continue. Initially it was assumed that the sector would operate at capacity for no more than one hour without either the controller changing or the traffic declining. The amount by which the traffic flow was to be set at a lower rate in order for safe operation to continue was studied further. While it was assumed that the time spent per strip check, which determined the weight given to the planning workload, was two seconds, the following conclusions were derived:

“THE AVERAGE WORKLOAD AT CAPACITY MUST BE LESS THAN 80 PER CENT AND WORKLOADS OF 90 PER CENT MUST NOT BE EXCEEDED MORE THAN 2.5 PER CENT OF THE TIME.”