Iteration is the key to the success of the conceptual design activities; the moving forwards and backwards between the design activities until finally the airspace design is sufficiently mature to make it possible to move on to the Validation phase
For both en-route and terminal airspace, the design of airspace is an iterative process, which places significant reliance on qualitative assessment and operational judgement of controllers and airspace
Once Planning Phase is complete by Activity 6, an activity which has identified the ‘future environment’ (characterised by enablers, constraints, and assumptions) the team is now ready to design the airspace. The availability of independent surveillance (i.e. Radar as opposed to ADS-B only) across most of the European continent means that the airspace design benefits more from PBN than would be the case in an airspace without radar surveillance. PBN allows, particularly in the terminal areas repeatedly used radar vectoring paths to be replicated with RNAV or RNP SIDs/STARs thereby reducing the need for controller intervention.
The reliance on navigation performance through a navigation specification as the basis of ATS route placement is significant for the route planning in en route and terminal airspace. Whilst airspace planners know that connectivity between en route and terminal routes must be assured, if a different navigation specification is required in en route airspace to the one used for SIDs/STARs, the route spacing possibilities in en route and terminal can be different requiring a transition area where the route spacing is adjusted. Consequently, PBN specified area navigation ATS Routes whether in the en route or terminal need to be fully integrated and an understanding of plans/strategies in the connecting airspace is required.
For terminal airspace changes it is important that the procedure designer be fully integrated in the conceptual design process, but the placement of ATS Routes and particularly their interaction (specifically SIDs/STARs) should be decided by the operational ATCs managing that airspace in close consultation with airspace users. The importance of the procedure designer is not to be underestimated: whilst the ATM personnel with the AUs are key to deciding where routes are to be placed and how are they interact (this is not the job of the procedure designer), the procedure designer is key to determining the feasibility of the intended route placement as regards, for example, potential flyability. So whilst the conceptual design is led by the operational controllers who will seek the best route placement from an efficient traffic management perspective, the routes must be flyable and the AUs must buy into the schema and participate in its conception.
Airspace design usually follows this order for PBN implementation:
(i) First the the SIDs/STARs and ATS Routes are designed conceptually; (Activity 7)
(ii) Second, an initial procedure design is made of the proposed traffic flows (Activity 8) [this paves the way for finalising the Procedure design in Activity 12].
(iii) Third, an overall airspace volume is defined to protect the IFR flight paths (e.g. a CTA or TMA) and then this airspace volume is sectorised (Activity 9);
As suggested by the diagram below, Activities 7 to 9 do not follow a linear progression. Iteration is the key to the success of these three activities; the moving forwards and backwards between the activities until finally the airspace design is sufficiently mature to make it possible to move on to Activity 10 onward.
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