Building a robust navigation infrastructure for Performance Based Navigation (PBN)

9 February 2018

EUROCONTROL has built up considerable expertise over the years in Performance Based Navigation (PBN), which is a key enabler for airspace efficiency improvements. In helping driving PBN forward, the Agency works very closely with EUROCAE, the European body tasked with developing industry standards for aviation that are globally recognised.

Currently, a hot topic in PBN is how best to use positioning provided by Distance Measuring Equipment (DME) to support Required Navigation Performance (RNP) arrival and departure procedures. RNP enables aircraft to fly more precise paths, including repeatable turns, between two 3D-defined points in space. All navigation (including PBN) relates to position in space, and a key feature of RNP is that the use of GPS position is mandatory. If one or more aircraft lose GPS, DME can rise to the occasion. Thanks to continued evolution over decades, it is now a high-quality ground-based ranging source – but is not formally well recognised as such. If GPS has a problem, then positioning using multiple DME can serve as a ‘back-up’, and allow RNP arrival and departure operations to continue. Importantly, it would allow air navigation service providers (ANSPs) to continue to apply such RNP procedures, rather than reverting to conventional procedures which could adversely affect airspace capacity. DME plays a significant role in European aviation: European States have made significant investments both in terms of ground infrastructure and avionics, so due recognition is needed.

To this end, EUROCAE’s WG107 was created to document DME’s excellent modern performance so that it can be used for the purpose of RNP reversion. As DMEs are already used with precision landing systems, this means that many DME facilities in Europe contain high-performance integrity monitors. WG 107 aims to examine “RNP Reversion using DME/DME Positioning”. EUROCONTROL’s Gerhard Berz, from its Navigation & CNS Research Unit, was asked to chair the Group, with Maurizio Scaramuzza from Skyguide being elected as WG secretary. The group comprises a wide range of industry experts from the various related domains (DME avionics, flight management systems, DME civil and military ground system providers, etc.).

WG107 kicked off in November 2017 in Paris. Its expected outputs are the drafting of a new MASPS (Minimum Aviation System Performance Standard) to describe the overall system requirements and compliance methods for RNP reversion based on DME; and in parallel, the updating of ED-57, the DME ground transponder Minimum Operational Performance Standard (MOPS), which dates back to 1986. The MOPS update of ED-57 will also be led by EUROCONTROL‘s Valeriu Vitan, from its Navigation & CNS Research Unit.

This combined effort will improve the robustness of the network to large-scale GNSS outages (which are unlikely but nonetheless possible) by allowing stakeholders more formally to take advantage of current equipment capabilities, and to optimise their ability to support all PBN applications. While the updated standards will not require any on-board equipment changes, the guidance provided may nonetheless also make a contribution to further improving future ground and airborne navigation systems. WG107 hopes to complete the MASPS and MOPS by the end of 2019.

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