In aviation, performance-based navigation (PBN) is a specification issued by the International Civil Aviation Organization (ICAO). In PBN, aircraft required navigation performance (RNP) and area navigation (RNAV) systems performance requirements are to be defined in terms of accuracy, integrity, availability, continuity, and functionality required for the proposed operations in the context of a particular airspace, when supported by the appropriate navigation infrastructure.
In aviation, performance-based navigation (PBN) is a specification issued by the International Civil Aviation Organization (ICAO). In PBN, aircraft required navigation performance (RNP) and area navigation (RNAV) systems performance requirements are to be defined in terms of accuracy, integrity, availability, continuity, and functionality required for the proposed operations in the context of a particular airspace, when supported by the appropriate navigation infrastructure.
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In aviation, performance-based navigation (PBN) is a specification issued by the International Civil Aviation Organization (ICAO). In PBN, aircraft required navigation performance (RNP) and area navigation (RNAV) systems performance requirements are to be defined in terms of accuracy, integrity, availability, continuity, and functionality required for the proposed operations in the context of a particular airspace, when supported by the appropriate navigation infrastructure.
Background
Area navigation techniques and specifications started to evolve regionally without overall ICAO guidance. This consequently meant that terms and definitions such as "RNAV" and "RNP" had slightly different meanings in different regions of the world, and even other terms could be used locally. An example of this is the term "P-RNAV" (Precision RNAV) that Europe still uses (2019), which elsewhere is called "RNAV 1".
The terms RNAV and RNP was earlier used with little functional difference. RNP required a certain level of performance but made no attempt to define how it was to be guaranteed.
Performance-based navigation (PBN) is ICAO's initiative to standardise terminology, specifications and meanings. One example is to standardise the terminology used around APVs (Approaches with vertical guidance). All APVs have until recently been designated as RNAV-approaches, while these in fact are RNP-approaches with respect to the PBN implementation. All APVs require on-board performance monitoring and alerting, so the system cannot only be capable of navigation down to the required degree of accuracy, but also needs to continuously monitor the performance and be capable of alerting the pilot if its performance falls below that which is required.
Historically, aircraft navigation specifications have been specified directly in terms of sensors (navigation beacons and/or waypoints). A navigation specification that includes an additional requirement for on-board navigation performance monitoring and alerting is referred to as a required navigation performance (RNP) specification. One not having such requirements is referred to as an area navigation (RNAV) specification.
Performance requirements are identified in navigation specifications, which also identify the choice of navigation sensors and equipment that may be used to meet the performance requirements. The navigation specifications provide specific implementation guidance in order to facilitate global harmonisation.
Under PBN, generic navigation requirements are first defined based on the operational requirements. Civil aviation authorities then evaluate options in respect of available technology and navigation services. A chosen solution would be the most cost-effective for the civil aviation authority, as opposed to a solution being established as part of the operational requirements. Technology can evolve over time without requiring the operation itself to be revisited as long as the requisite performance is provided by the RNAV or RNP system.
PBN offers a number of advantages over the sensor-specific method of developing airspace and obstacle clearance criteria:
reduces the need to maintain sensor-specific routes and procedures, and their costs. For example, moving a single VOR can impact dozens of procedures, as a VOR can be used on routes, VOR approaches, missed approaches, etc. Adding new sensor-specific procedures would compound this cost, and the rapid growth in available navigation systems would soon make sensor-specific routes and procedures unaffordable;
avoids the need for developing sensor-specific operations with each new evolution of navigation systems, which would be cost-prohibitive. The expansion of satellite navigation services is expected to contribute to the continued diversity of RNP and RNAV systems in different aircraft. The original basic global navigation satellite system (GNSS) equipment is evolving due to the development of augmentations such as satellite-based augmentation systems (SBAS), ground-based augmentation systems (GBAS) and ground-based regional augmentation systems (GBAS), while the introduction of Galileo and the modernisation of the United States' Global Positioning System (GPS) and the Russian Global Navigation Satellite System (GLONASS) will further improve GNSS performance. The use of GNSS/inertial integration is also expanding;
allows for more efficient use of airspace (route placement, fuel efficiency and noise mitigation);
clarifies how RNAV systems are used; and
facilitates the operational approval process for civil aviation authorities by providing a limited set of navigation specifications intended for global use.
Within an airspace, PBN requirements will be affected by the communication, surveillance and air traffic control (ATC) environments, the navaid infrastructure and functional and operational capability needed to meet the ATM application. PBN performance requirements also depend on what reversion, non-RNAV means of navigation are available and what degree of redundancy is required to ensure adequate continuity of operations.
To achieve the efficiency and capacity gains partially enabled by RNAV and RNP, the FAA will pursue use of data communications and enhanced surveillance functionality.
These approaches had some confusing names and designations on charts, and the changeover is currently being conducted across all member states. The two types of RNAV-approaches have traditionally been named RNAV (GNSS) and RNAV (RNP) respectively, where the former is the traditional straight-in approach from the final approach fix, and the latter is a more complex approach that curves in the horizontal plane after the final approach fix which requires authorization for it to be commenced (AR = Authorization Required). The correct naming and designation for these approaches under the PBN implementation are RNP and RNP AR respectively. The images to the right show the naming of the current charts being used, and what they will look li
