PBN is an umbrella term for Area Navigation (RNAV) / Required Navigation Performance (RNP) specifications and was created to simplify the language used when listing requirements for different airspace.Letters of Authorization (LOAs) may be issued based on the “PBN requirements” of various airspaces.
The PBN concept is primarily intended to structure navigation specifications according to Required Navigation Performance (RNP), and is further subdivided according to phase of flight (e.g., terminal, continental, oceanic, and approach). The number described by an RNP specification is an accuracy threshold for the navigation equipment –that is, the maximum distance (NM) that the sensors could deviate for 99% of the time the aircraft is operating in that portion of flight. Accordingly, the lower the RNP value is, the more accurate the equipment is, and therefore the higher the standard that is being applied.
Most Civil Aviation Authorities, including the FAA,have a separate PBN authorization for each phase of flight. It is recommended that operators obtain an LOA for each phase to clarify their capabilities when operating internationally, as the authorization requirements for each phase of flight vary throughout the world. For example, although no LOA is required for Part 91 operators to conduct terminal PBN operations in the United States, some countries, such as Hong Kong and Australia, do. LOA C063 can be used to demonstrate that the operator is capable of terminal RNP-1 operations in those countries.