- 1 Introduction
- 2 Navigation capability
- 3 RNP Operations
- 4 Conclusion
- 5 See also
- 6 Reference
- 7 Author
Planes were made as a means of transport. To successfully fly from a location A to a location B, pilots were first and foremost navigators. Originally relying on visual landmarks such as cities, rivers, terrain or roads, they then used to navigate using newer technologies based on radio systems such as NDB and VOR.
We will now explain the key concepts that should not be mixed up and that are commonly not precisely understood.
Performance based navigation (PBN)
PBN will allow using with more efficiency the RNAV and RNP systems leading to optimized airspace in terms of fuel efficient and noise-reduced routes and procedures. In addition, as it is based on these systems, it allows aircraft changing from sensor-based navigation, to performance-based navigation.
Area Navigation (RNAV)
When a procedure is said to be RNAV, it means that if the aircraft position is computed with enough precision, the flightpath will be flyable without necessarily relying on ground sensors such as radio aids. In fact, a simple satellite signal (by means of GPS) will allow flying through non-physical waypoints (i.e. only plotted with coordinates, and not by two VOR radials for example). Finally, most complete procedures will make flying these waypoints at, below or above an altitude, a complete 3D flightpath.
Required Navigation Performance (RNP)
It is the key difference with RNAV. It allows reducing procedures margins at the benefit of optimized flightpaths. However, the required performance is strongly increased, up to the tenth of a nautical mile. This requirement will be adapted to the phase of the flight.
Phase of flight
We distinguish three different PBN en-route applications:
- RNAV 5 (Basic RNAV ~ B-RNAV)
- RNAV 1 (Precision RNAV ~ P-RNAV)
- Advanced RNP ~ A-RNP
We distinguish four different PBN terminal applications:
- RNAV 1 (P-RNAV)
- Basic RNP 1
- Advanced RNP
- RNP Authorisation Required ~ RNP-AR
We distinguish four different approach applications:
- RNP APCH – Non Precision Approach (NPA) with 2D Path Guidance
- RNP APCH – Approach with Vertical Guidance (APV) ~ 3D Path Guidance
In addition, RNP operations will allow monitoring of the performance and alerting in case of loss of accuracy. Monitoring of the performance by the crew is mandatory (ANP versus RNP) Given this system, RNP operations allow flying 99% of the flight time within a radius of 2*x miles around the centerline of the desired flightpath.
Basic RNP (RNP 1)
It concerns SID/STAR and Initial Approach operations. In mountainous regions, it allows more optimized flight paths than RNAV operations.
- RF required (we can see it with the various ARC segments), requires RNP 0.30 till VAPLI !
Advanced RNP (A-RNP)
Benefits will include:
- Optimized Lateral Navigation: closer routes, constant spacing requirements even on turning segments, reduced holding area, and contingency offset routes to avoid radar vectoring.
- Optimized Vertical Navigation: cleaner separation of arrival and departure flows, effective use of Continuous Descent/Climb Operations (CDO/CCO).
- Optimized Longitudinal Navigation: Management of entry/exit time between Terminal Area and Enroute Area
RNP Approach (RNP APCH)
These approaches are created for the following reasons:
- Non-existent instrument procedures
- Replacement for old generation instrument procedures
- Enhancement of existing procedures in terms of environmental concerns (noise, terrain, …)
Authorization Required APCH (AR APCH)
This restriction allows demanding another level of accuracy, as low as 0.1NM:
- Along the final segment and initial segment of a missed approach : RNP0.1 and RF segments
- Other segments : RNP0.3
We will study the chart of Kathmandu RNP AR APCH RWY02
On this chart, we can extract the following information:
- Authorization Required
- Minimum Temperature -10°C
- Missed Approach RNP0.30
- This procedure contains several RF segments
RNP operations are another shift in the way aircraft are operated. Today’s navigation is more and more focused toward optimization of flightpaths while ensuring safety.
This shall lead to an environment-friendly aviation, taking into account sensitive areas in regard to terrain and noise as decisive factors.
While flightpaths are more and more precise, from 2D projections to 4D projections, requirements are more and more demanding in terms of equipment and reliability.
- VID 200696 - Creation
- VID 150259 - Wiki integration
DATE OF SUBMISSION
- 00:30, 14 May 2021
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