Activities 7-8-9 can be viewed as the kernel of the airspace design concept. The notification through public consultation of the intention to design new routes initiated at the start of the project and returned to during Activity 3, now enters a more concrete phase during activities 7-9. The routes/flows are designed conceptually in terms of placement and interactions (7). These routes/flows are then refined using obstacle clearance criteria (PANS-OPS) to determine whether they are flyable and realistic (8). Iterations follow between the conceptual and obstacle clearance ‘design’ and then sectors are drawn up (9) to manage the traffic i.e. assign the routes to a sector. A three-way ‘fitting exercise’ is then needed between the planned route placement, the obstacle criteria viability/flyability and the sectors which, of course, abut onto other sectors. This three-way iteration process can therefore become lengthy and can cause traffic flows to be moved, climb gradients to be changed, sectors to be re-shaped.
Operationally, this entire process requires close coordination and consultation with (operational) stakeholders forming part of the airspace design team dimensioned for purposes of the activity in progress. The ‘freedom’ of where to ‘place’ the routes is not limitless, however, despite PBN’s facilitation.
The decision regarding the placement of routes and instrument flight procedures is for the Airspace Design Team and key consultation partners often a struggle between competing interests requiring negotiation and trade offs.
The placement of flight paths especially immediately after departure and arrival to land has increasingly become a political issue for neighbouring communities, local council and government and this may have resulted in criteria to be respected by the airspace design team. Such policy matters may require the provider of ATM/ANS (through its airspace design team) to comply with a variety of criteria when preparing the airspace change, for example:
From an ATM perspective, it is often less complex and less workload intensive (and therefore safer) to have one or a set of well-defined departure flight paths off each departure runway, and to couple those flight paths to required climb gradients and aircraft power settings. Curfew measures and even aircraft movement quotas are increasingly becoming the norm. These are typical examples of trade offs.
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