Area Navigation (RNAV) is a method of air navigation that permits aircraft operation on any designated flight path, such as a direct route between airports or parallel routes independent from the fixed routes between navigational aids (NAVAIDs). Various navigational data sources such as radials from VHF Omni Range (VOR), distance from Distance Measurement Equipment (DME), and position data from Global Positioning System (GPS) are used to calculate the position and flight path of an aircraft. The accuracy of RNAV is indicated by the number “x” of RNAV-x, RNAV-5 for example. The number “x” shows the tolerated magnitude of error in NM for a 95 percent probability.
Required Navigation Performance (RNP) as a concept applies to navigation performance within the airspace and therefore affects both the airspace and the aircraft. RNP is intended to characterize airspace through a statement of the navigation performance accuracy (RNP type) to be achieved within the airspace. The RNP type is based on a navigation performance accuracy value that is expected to be achieved at least 95 percent of the time by the population of aircraft operating within the airspace. The development of the RNP concept recognizes that current aircraft navigation systems are capable of achieving a predictable level of navigation performance accuracy and that more efficient use of available airspace can be realized based on this navigation capability.
Performance-Based Navigation (PBN) is another operational concept that links the navigation standards to the navigation accuracy and integrity of an aircraft. RNAV and RNP are both included in PBN. The navigational performance of an aircraft is approved by State civil aviation authority within one or more specific categories.