Faculty of air transport engineering the department of «air navigation systems»

1.1.5 Building RNP schemes.
RNP schemes were included in the PANS-OPS document (Doc 8168), which began to be applied in 1998. These RNP schemes were a precursor to the current PBN concept, which defines the characteristics for en-route flight, rather than just the required radio navigation system. However, due to the lack of detailed description of navigation characteristics and operational requirements, it seemed that RNAV and RNP were not much different from each other. In addition, as a result of the inclusion of conventional flight elements, such as "fly-over" schemes, flight path variability and additional buffer airspace, significant advantages in the construction of schemes could not be obtained. As a result, there were no benefits to the users/society, and implementation was either non-existent or very little implemented.
Area navigation using PBN is a performance-based operation that clearly specifies the navigation characteristics of the aircraft, and the problems outlined above with respect to the original RNAV and RNP criteria can be resolved. Performance-based operation descriptions provide solutions to the problems associated with different aircraft characteristics that have caused changing flight paths, and provide greater repeatability, reliability and predictability of the flight path, as well as smaller obstacle assessment areas. Examples of RNP APPROACH (RNP APCH) and RNP AUTHORIZATION REQUIRED APPROACH (RNP AR APCH) are shown in Fig. I-A-3-6.

Figure 5. Examples of RNP APCH (left) and RNP AR APCH (right) schemas)

The main change in the work of the developers will be that they will not develop a scheme for a specific sensor, but in accordance with the navigation specification (for example, RNAV 1). The selection of the appropriate navigation specification is based on the requirements for the airspace, the available navigation infrastructure, and the equipment and operational capabilities of the aircraft that are expected to use the route. For example, if an RNAV-1 or RNAV-2 is required in the airspace, the available navigation infrastructure must be a basic GNSS or DME/DME, and aircraft will be required to use either of these for flight operations. Volume II of this aircraft and operator's manual provides a clearer and more complete description of the navigation specification than volume I of PANS-OPS (Doc 8168). As a result of the construction of such a scheme and the qualification suitability of aircraft and the operator, the reliability, repeatability and predictability of the flight path of aircraft increases. It should be borne in mind that, regardless of the infrastructure provided, the developer can still apply the same general construction rules when placing control points and trajectories, however, based on the appropriate criteria for the height of the obstacle flight or separation, additional adjustments may be required.
The integration of aircraft and operational criteria in this manual will update the design criteria for schematics. As a first step, such criteria are created for the RNP AR APCH navigation specification. In this case, the construction criteria fully take into account the capabilities of the aircraft and are fully integrated with the requirements for the approval of the aircraft and the qualification assessment. The closely integrated relationship between aircraft and operational criteria and design criteria for RNP AR APCH requires a closer examination of the aircraft qualification assessment and operator approval, as special authorization is required. As a result of this additional requirement, airlines will incur costs, and these types of schemes will become cost-effective only in cases where other scheme design criteria and solutions do not fit.