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Required navigation performance (RNP) is a type of performance-based navigation (PBN) that allows an aircraft to fly a specific path between two 3D-defined points in space. RNAV and RNP systems are fundamentally similar. The key difference between them is the requirement for on-board performance monitoring and alerting. A navigation specification that includes a requirement for on-board navigation performance monitoring and alerting is referred to as an RNP specification. One not having such a requirement is referred to as an RNAV specification. RNP also refers to the level of performance required for a specific procedure or a specific block of airspace. An RNP of 10 means that a navigation system must be able to calculate its position to within a circle with a radius of 10 nautical miles. An RNP of 0.3 means the aircraft navigation system must be able to calculate its position to within a circle with a radius of 3 tenths of a nautical mile.〔(PBN Learning Center | GE Aviation Systems | GE Aviation )〕 A related term is ANP which stands for "actual navigation performance". ANP refers to the current performance of a navigation system while "RNP" refers to the accuracy required for a given block of airspace or a specific instrument procedure. Some oceanic airspace has an RNP of 4 or 10. The level of RNP an aircraft is capable of determines the separation required between aircraft. RNP approaches with RNP values currently down to 0.1 allow aircraft to follow precise three-dimensional curved flight paths through congested airspace, around noise sensitive areas, or through difficult terrain.〔 In 1996, Alaska Airlines became the first airline in the world to utilize an RNP approach with its approach down the Gastineau Channel into Juneau, Alaska. Alaska Airlines Captain Steve Fulton and Captain Hal Anderson developed more than 30 RNP approaches for the airline's Alaska operations. In 2005, Alaska Airlines became the first airline to utilize RNP approaches into Reagan National Airport to avoid congestion.〔(Alaska Airlines Becomes First Carrier Authorized To Conduct RNP Precision Approach Flight Validations )〕 In April 2009, Alaska Airlines became the first airline to gain approval from the FAA to validate their own RNP approaches.〔 On 6 April 2010, Southwest Airlines converted to RNP. Since 2009, regulators in Perú, Chile, and Ecuador have deployed more than 25 RNP-AR approach procedures, designed in conjunction with LAN Airlines. Benefits included reduction in greenhouse gases emissions and improved accessibility to airports located on mountainous terrain. The use of RNP-AR approaches in Cusco, near Machu Picchu, has reduced cancellations due to foul weather by 60 percent on flights operated by LAN. In October 2011 Boeing, Lion Air, and the Indonesian Directorate General of Civil Aviation, performed validation flights to test tailor-made Required Navigation Performance Authorization Required (RNP AR) procedures at two terrain-challenged airports, Ambon and Manado, Indonesia as pioneering the use of RNP precision navigation technology in South Asia.〔(【引用サイトリンク】title=Boeing & Lion Kick Off RNP Flight Operations )〕 ==Description== The current specific requirements of an RNP system include: * Capability to follow a desired ground track with reliability, repeatability and predictability, including curved paths; and * Where vertical profiles are included for vertical guidance, use of vertical angles or specific altitude constraints to define a desired vertical path. RNP APCH supports all leg types and path terminators used in standard RNAV, including TF and RF. RNP AR procedures support only two leg types: * TF leg: Track to fix, a geodesic path between two fixes. * RF leg: Radius to fix. This is a curved path supported by positive course guidance. An RF leg is defined by a radius, arc length and a fix. Not all RNP capable FMS systems support RF legs. The performance monitoring and alerting capabilities may be provided in different forms depending on the system installation, architecture and configurations, including: * display and indication of both the required and the estimated navigation system performance; * monitoring of the system performance and alerting the crew when RNP requirements are not met; and * cross track deviation displays scaled to RNP, in conjunction with separate monitoring and alerting for navigation integrity. An RNP system utilises its navigation sensors, system architecture and modes of operation to satisfy the RNP navigation specification requirements. It must perform the integrity and reasonableness checks of the sensors and data, and may provide a means to deselect specific types of navigation aids to prevent reversion to an inadequate sensor. RNP requirements may limit the modes of operation of the aircraft, e.g. for low RNP, where flight technical error (FTE) is a significant factor, manual flight by the crew may not be allowed. Dual system/sensor installations may also be required depending on the intended operation or need. An RNAV system capable of achieving the performance requirements of an RNP specification is referred to as an RNP system. Because specific performance requirements are defined for each navigation specification, an aircraft approved for a RNP specification is not automatically approved for all RNAV specifications. Similarly, an aircraft approved for an RNP or RNAV specification having stringent accuracy requirements is not automatically approved for a navigation specification having a less stringent accuracy requirement. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「required navigation performance」の詳細全文を読む スポンサード リンク
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