Area Navigation (RNAV) is defined as a method of navigation which permits aircraft operation on any desired flight path within the coverage of station-referenced navigation aids or within the limits of the capability of self contained aids, or a combination of these. Many countries offer or are planning to offer RNAV routes as part of the ATS structure; some exploit the capabilities of Precision RNAV equipment to offer random RNAV routing. PBN is being pushed by ANSPs as the future of airspace redesign but poor implementation has resulted in varied results. Free Route Airspace (FRA) is one aspect of this topic. We were introduced to what FRA is and that it is not freedom to route where they wish, merely a removal of the limited number of strict airways routings within a region.

The driver for this is allowing airlines to plan for the most efficient route thereby reducing fuel uplift. This can be implemented in three ways:

  • Direct route segments – existing infrastructure maintained but option to file point-to- point
  • Organized Track Systems – flight plan requests are made and defined routes are created based upon demand
  • Free Route Airspace – no routes, simply file point-to-point

The challenge for ATCOs is that we are not as good at spotting conflicts in a route free environment. Consequently, a conflict detection tool may be beneficial which monitors separations to assist the Controller in maintaining safety.

IFATCA Policy is:

Controllers should be presented with information, by any suitable means, concerning navigational capability of aircraft under their control.

In airspace where dynamic and flexible ATS routes are permitted, the ATS system should be capable of processing associated flight plans

Trajectory prediction and conflict detection tools should be available on situation displays used to control airspace where dynamic and flexible ATS routes are permitted.

Where the introduction of PBN procedures entail closely spaced parallel tracks, suitable procedures should be established for the case of loss of navigational performance, taking into account such factors as ground equipment capability and controller training.

Adequate training must be provided for controllers managing PBN operations; such items as RTF phraseology, co-ordination procedures and conflict identification need to be considered.

IFATCA should ensure that controllers’ expertise is used in the deliberations taking place to provide appropriate specifications for the use of PBN.

PBN route structures must be designed to ensure that ATC workload is not increased when compared to previous conventional route structures and, where possible, it is reduced in spite of increased traffic.

RNAV and RNP standards should be harmonized throughout the world and included in the PBN Manual.  Harmonisation will result in common standards, decreasing the diverse types of RNAV and RNP procedures that are currently encountered by air crews operating around the world.

The development, validation and implementation of PBN procedures should involve all affected parties, in particular, local operational controllers and representatives of airspace users.

Organizational processes and support should exist for operational staff to initiate airspace and procedure changes.

The introduction of PBN procedures shall be accompanied by training for controllers and pilots that is commensurate with the complexity of the procedure.

See: WP 88 – Christchurch 1993, WP 98 – Hong Kong 2004, WP 91 – Arusha 2008, Resolution B1, B2, B3 – WP 158 – Las Vegas 2016 and Resolution B4, B5 – WP 161 – Las Vegas 2016


Last Update: September 29, 2020  

November 3, 2019   256   Jean-Francois Lepage    AAS    

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