PBN is a powerful airspace design tool for routes and procedures: it allows routes to be placed in the most strategically beneficial location to ensure strategic de-confliction of flight paths thereby reducing the need for ATC intervention. This single PBN benefit provides spin-off benefits in terms of capacity, safety, flight and ATM efficiency and potentially, environmental mitigation. PBN’s relationship with environmental mitigation has been a mixed one, particularly because a misunderstanding arose where PBN was ‘blamed’ for making it possible to place routes in locations which generated some form of nuisance (visual intrusion, noise, emissions). It is important to grasp that the placement of routes in the vicinity of an airport (SIDS/STARs) is a hugely contentious issue in airport neighbouring communities. Often, enduring ‘battles’ end up in the court where citizens refuse to have routes over their homes and local authorities, seeking to remain part of supply chains, boost tourism, generate jobs, fiercely battle to grow airports and attract more traffic. Operationally, the freedom provided to the airspace designer by PBN whereby routes can be placed anywhere, is actually a limited freedom. The sensitivity of airport neighbourhoods and environmental pressures mean that route placement is increasingly becoming a political issue, sometimes to the detriment of the operational benefit of strategic de-confliction.
PBN’s global ‘standardisation’ mechanism at aircraft level (through the publication PBN specifications from which authorities should not deviate), means that an RNAV 1 aircraft certified by its authority in State A is qualified to operate in State B. This interoperability is a huge cost benefit.
Controlled Flight into Terrain (CFIT) remains one of the greatest causes of loss of life in aviation today. This is what prompted ICAO’s first PBN resolution 36-23 followed by the updated resolution 37-11 to strongly encourage approaches with vertical guidance: stabilized approaches and reduction of CFIT were the objective. To accommodate the reality that 3D approaches could not be executed everywhere in the world (some places have no QNH needed by Barometric VNAV, and others have no SBAS coverage needed for RNP APCH), the resolutions were slightly diluted to permit 2D approaches but actually pushing for 3D approaches. This 3D option is the one followed in Europe: the PBN Implementing Regulation requires, by December 2020, all instrument runway ends not having an ILS, to have a published RNP APCH with three lines of minima (LNAV, LNAV/VNAV and LPV). By January 2024, all instrument runway ends in the EU + regulated states, will have an RNP APCH with three lines of minima.
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