Required navigation performance approach

Required navigation performance (RNP) approaches improve safety and provide better access to runways that are not equipped with precision approach and landing aids.

The European Commission Implementing Regulation (EU 2018/1048) stipulates that RNP approaches with vertical guidance have to be implemented at all instrument runway ends.

Approach procedures to lateral navigation (LNAV), lateral/vertical navigation (LNAV/VNAV) and lateral precision with vertical guidance approach (LPV) minima are to be implemented by:

• December 2020 on runways currently served only by non-precision approaches; and
• January 2024 on runways currently served by precision approaches.

EUROCONTROL supports the implementation of these procedures, bringing stakeholders together through the RNP implementation Support Group (RAiSG) to share best practices and lessons learned. Documentation associated with this group is available on the EUROCONTROL’s working group RAISG Onesky Teams (accessible only to registered users).

A unique number, the SBAS channel, is required for RNP approaches to LPV or LP minima. EUROCONTROL used to be the focal point in Europe for distributing and managing the SBAS channel numbers. This function was taken over by ICAO in 2019 when a unique world-wide allocation mechanism was put in place.

We developed:

• the PBN map tool to illustrate the status and plans for implementing RNP approaches in the European Civil Aviation Conference area;
• an FAS DB tool that that computes the relevant cyclic redundancy check (CRC) remainder and generates an electronic file as well as a text description to support LPV procedure publication. It generates the final approach segment (FAS) data block which is required for all SBAS-based approaches.

In the context of the ICAO Performance Based Navigation (PBN) concept, required navigation performance (RNP) is a family of navigation specifications which allow aircraft to operate along a precise flight path. It gives the aircraft the ability to determine its position with both accuracy and integrity. RNP allows an aircraft to fly a specific path between two 3D-defined points in space.

Navigation specifications for RNP approaches are published in the ICAO PBN Manual where several types of approach are defined.

• RNP approach operations down to LNAV and LNAV/VNAV minima: lateral guidance is provided by a global navigation satellite system – GNSS - and vertical guidance by barometric/VNAV;
• RNP approach operations down to LP and LPV minima: lateral and vertical guidance provided by a satellite-based augmentation system (SBAS)

Guidelines for the implementation of RNP approaches are published in ICAO reference document 025.