This activity can be viewed as a preliminary validation assessment of the routes and holds. Flyability must be achievable and the performance requirements coherent with the selected Navigation Specification. This activity could have iterations with Activities 7 & 8.
Once the airspace design is complete: the placement of flows have been agreed and have been assessed by the procedure designer, the flows are protected within defined airspace and the workload has been balanced through appropriate sectorisation, it is important to step back and verify that the design can indeed be supported by the navigation specification identified in Activity 6.
This task should be a relatively simple activity if steps 6 – 9 have been done in an integrated and collaborative manner and if Activity 6 has definitively identified one particular specification as the basis for the design. In such cases, this step can be used to refine the choice between two competing navigation specifications with the same lateral performance and to decide on one of the two bearing in mind the CBA, and compliance with regulatory requirements.
Alternatively, it may be viable to have provided for two sets of design each based on different navigation specifications. Both could then be subjected to an in-depth feasibility assessment to establish the final choice. The confirmation of chosen Navigation Specification can be quite complex - even once the airspace concept has been completed and the validation phase looms.
In the ECAC area of Europe where the initial intent of implementing RNAV 1 foreseen for the 1990s had to be scaled 'back' to an RNAV 5 implementation when it became clear nearly three years before the 1998 implementation date that the expected natural replacement of the older equipment meeting RNAV 5 with systems compatible with RNAV 1 was much slower than expected. This example serves to emphasise, again, the importance of fixing realistic assumptions in Activity 6.
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