RNP 10 ➔ 4 RNP 0.3 ➔ 0.1 RNP 5 ➔ 1 RNP 12 ➔ 4 RNP 4

RNP 4 RNP 10 ➔ 4 FLIGHT OPERATIONS JEFF AIMAR RNP 10 ➔ 4 ASSOCIATE TECHNICAL FELLOW AIR TRAFFIC MANAGEMENT SERVICES BOEING COMMERCIAL AIRPLANES GROUP

AERO 26 REQUIRED NAVIGATION PERFORMANCE FOR IMPROVED FLIGHT OPERATIONS AND EFFICIENT USE OF AIRSPACE equired navigation per- beacons. See “Traditional and Area INDUSTRY EXPANSION OF Technical Commission for Aeronautics formance (RNP) extends Navigation” on p. 34.) 2 ICAO RNP (RTCA) and the European Organisation for 2 x RNP R the capabilities of modern ICAO defined RNP as “a statement of While the ICAO definition of RNP Civil Aviation Equipment (EUROCAE)— airplane navigation systems by the navigation performance accuracy adequately specified 95 percent accuracy expanded the definition of RNP to include providing real-time estimates of necessary for operation within a performance, it did not quantify other a new lateral containment limit and defined airspace.” This navigation navigation uncertainty, assurance common navigation parameters normally minimum navigation system capabilities. performance accuracy is quantified of performance through its con- used by industry during equipment design These additional requirements are with two values: a distance in nautical tainment concepts, and features and certification. It also lacked a way to documented in the “Minimum Aviation miles (known as the RNP type) and RNP that ensure the repeatability and System Performance Standards (MASPS): a probability level. For example, an statistically specify potential rare excur- predictability of airplane naviga- Required Navigation Performance for airplane is qualified to operate on an sions from the desired path. Two aviation tion. This precise characterization Area Navigation,” issued by the RTCA. RNP 10 airway if it has demonstrated standards organizations—the U.S. Radio of airplane performance is key to that the capability and performance designing more efficient airspace of the airplane navigation system will ICAO RNP 10 EXAMPLE routes and procedures. result in the airplane’s being within 1 FIGURE Before introducing RNP operations 10 nmi of the indicated position RNP RNP into their fleets, operators should on the navigation system at least 95 percent of the flying time (fig. 1). understand the following: RNP The most powerful feature of the ICAO 1. RNP as initially conceived RNP concept is the specification of a Actual airplane location within 10 nmi RNP by the International Civil minimum performance requirement with- 10 nmi Aviation Organization (ICAO). of navigation system out equipment mandates. This is a major position at least 2. Industry expansion of improvement over the previous method Desired 95% of flight time ICAO RNP. of deriving airspace design based on path traditional discrete navigation systems (airway) 3. RNP capabilities on Boeing or on a broad population of airplane 2 x RNP airplanes. navigation systems with widely varying 10 nmi 4. Assessment of RNP capabilities. performance. However, other factors besides navigation performance (such as 5. Operational approvals. 10 nmi 10 nmi intervention capability, traffic density, RNP The aviation industry projects that increasing demands and route structure) must be considered on airspace will result in more air travel delays and in determining the route separation related costs, unless the traditional system of airplane RNP AS INITIALLY CONCEIVED reduction possible with ICAO RNP (fig. 2). 1 BY THE INTERNATIONAL CIVIL navigation, monitoring, and control is changed. In AVIATION ORGANIZATION 2 ICAO RNP AIRSPACE BUFFER REDUCTION RNP leads to reduced buffers for route spacing and response, a new tool, called required navigation per- In 1983, the ICAO formed the FIGURE increased traffic capacity in the same airspace. formance (RNP), is being developed that will be a key Future Air Navigation System (FANS) Navigation performance Committee to develop a broad strategy POPP 10 nmi element in reducing en route airplane separation and, that included new methods for airplane as a result, increase airspace capacity. This tool communication, navigation, and sur- Pre-RNP RNP defines the navigation accuracy an airplane must have veillance, and air traffic management PLMN (CNS/ATM) (see “Operator Benefits of to operate within a defined airspace. Ensured naviga- FANS” in Aero no. 2, April 1998). The navigation element of CNS/ATM centers 60 to 100 nmi tion performance and standardized functionality of Mitigates navigation errors, on the concept of RNP. RNP provides Mitigates navigation errors, RNP allow new procedures to be designed for airports 5 x RNP, 6 x RNP route structure, traffic for the specification of airspace based navigation performance, route (50 to 60 nmi) density, surveillance, ATC, where infrastructure or terrain makes it difficult or on demonstrated levels of navigation structure, traffic density, sur- communication performance and certain functional veillance, ATC, communication impossible to use some runways. RNP also allows for capabilities, rather than a required set improvements to procedures that are demanding on of navigation sensors or equipment. flight crews. Boeing has been a leader in developing Area navigation (RNAV) functionality is a key element of the RNP concept. PWVG national and international technical standards for (Area navigation systems define RNP capability, which now is available on all Boeing waypoints by latitude and longitude Legend: coordinates and allow for navigation PLWX airplanes in production and in service. on any desired flight path rather than Desired path RNP 95% threshold one defined by ground-based radio

AERO AERO 28 29 Lateral containment limit. The new repeatable paths over the ground lower landing minimums, and reduced containment limit specifies an addi- 3 RNP RNAV CONTAINMENT for a given airway or procedure. Also workload, all of which contribute to 5 RNP SYSTEM SCHEMATIC tional requirement on navigation FIGURE specified in the MASPS was a real-time improved safety margins. FIGURE system uncertainty beyond the ICAO display of the estimated navigation Containment limit: 99.999% concept of 95 percent accuracy system accuracy (called “estimated RNP CAPABILITIES ON performance. The lateral (cross-track) position uncertainty” [EPU] or “actual 3 BOEING AIRPLANES dimension of this containment limit navigation performance” [ANP] on RNP RNAV functionality is available is twice the size of the RNP value and Boeing commercial airplanes). With on all Boeing commercial airplanes in RNP: 95% 2 x RNP centered on the airplane’s defined path an explicit display of EPU/ANP, the production and can be retrofitted on (fig. 3). The navigation system must flight crew can monitor trends while Boeing models delivered without ensure that the airplane remain within the navigation system automatically RNP capability. this containment region 99.999 percent checks current performance against The MASPS established all signifi- of the flight time. This outer linear Defined path required performance (i.e., the RNP cant aspects of navigation system containment region will be used to Desired path necessary for the operation). The assess the safe separation of airplanes system alerts the flight crew when performance, assurance, capability, and and obstacle clearance when develop- performance is inadequate for the functionality that must be considered ing routes, areas, and procedures. current operation. for RNP-based operations. Because many current systems will not meet RNP This industry-expanded specification Minimum navigation system every MASPS requirement, any system of RNP is called RNP RNAV to differen- capabilities. In addition to specifying deviations from the MASPS can be tiate it from the incomplete specifi- requirements for continuity and avail- mitigated through limitations or cation of RNP defined by ICAO. RNP operational procedures. This will allow ability of required positioning accuracy, Containment limit the MASPS specified capabilities to RNAV will be an aid in both separa- as many airplanes as possible to be ensure consistency of flight paths tion and collision risk assessments qualified during the transition to RNP ■ operations. The Boeing RNP RNAV and operations across the fleet. For RNP RNAV is referenced to the for proposed routes and procedures. example, the types of flight plan legs airplane defined path This will reduce route separation and designs have addressed all the key func- improve obstacle clearance limits tional and performance requirements that could make up RNP route seg- ■ ICAO RNP is referenced to the beyond those provided by ICAO RNP of the RNP MASPS. Further MASPS- ments were limited and standardized airspace desired path to ensure that all similarly equipped (fig. 4). Benefits include increased compliant changes to Boeing designs airplanes fly consistent and airspace capacity and efficiency, most likely will be warranted by operations and the evolution of RNP. Questions concerning MASPS compliance RNP 4 RNAV EXAMPLE for specific models should be directed 4 to Boeing Field Service representatives. FIGURE RNP RNAV is a tool to facilitate further optimization appropriate area on the crew alerting certification and limitations approved (reduction) in airspace buffers. Boeing RNP functionality includes message display. Other airplanes by the FAA and other regulatory flight crew interface through a flight (such as the 737 and MD-80) display authorities. The AFMs for Boeing management control display unit 4 nmi 8 nmi the message on the CDU, the naviga- airplanes certified for RNP RNAV (CDU) and the airplane crew alerting tion display, the primary flight display, capability contain some or all of the RNP RNP 4 RNAV 4 nmi system. Navigation, flight planning, or a combination of these. following information: and alerting algorithms are contained PLMN ■ The minimum demonstrated RNP in the airplane flight management ASSESSING RNP CAPABILITIES as a function of the lateral flight PLMN function (fig. 5). 4 control mode. This is the smallest Performance Mitigates navigation 4 x RNP The CDU is used for flight plan and Materials and references are available RNP value for which the airplane assurance 5 x RNP, 6 x RNP errors, route structure, (16 nmi) procedure selection and to display the to help operators assess the capabili- equipment has been certified to region (20 to 24 nmi) traffic density, surveillance, RNP for the active route segment and ties of Boeing RNP-equipped airplanes operate at a given lateral control ATC, communication the current navigation performance (or and to obtain regulatory approval to mode (e.g., the flight management ANP). RNP values can be stored in the conduct RNP operations. The materials system [FMS] lateral navigation PWVG database for route segments, manually and references include the Airplane with autopilot engaged). Values entered by the flight crew, or selected Flight Manual (AFM) for each airplane, are provided for an active and automatically, depending on the flight RNP capability documents, a Boeing inactive global positioning system PWVG phase (fig. 6). document for an industry RNP RNAV Note: Optimal case shown. Some (GPS). This accommodates buffer may be needed to mitigate Annunciation to the flight crew workshop, a U.S. Federal Aviation airplanes that do not use GPS to nonoptimal occurs when the ANP exceeds RNP. On Administration (FAA) RNP Web site, navigate and periods when satel- communications Legend: airplanes with crew alerting systems and software for personal computers. lite signals may not be available surveillance or high density. Defined path RNP 95% threshold (such as the 717, 747-400, 757, 767, to support operations that require Containment limit 777, and MD-90), a text message simi- Airplane Flight Manual. The AFM is GPS to achieve the desired level of lar to UNABLE RNP is displayed in the an information source on equipment RNP. The AFM notes that an RNP

AERO AERO 30 31 Flight Procedures Standards representatives. This ensures that 6 CDU POSITION REFERENCE PAGE Branch Web site. The FAA’s vision decisions on route or procedure 1 RNP CAPABILITY DOCUMENTS for implementing RNP in the U.S. configuration, adjacent route separa- FIGURE TABLE national airspace is explained on this tion, and obstruction clearance take Model Document number site (http://www.mmac.jccbi.gov/afs/ into account important factors such as afs420/OutReach/index.htm). the availability and quality of surveil- 737-300/-400/-500/-600/-700/-800 D6-39067-2 lance, communications, the navigation European Organisation for the Safety infrastructure, traffic density, and air 747-400 D926U050 of Air Navigation (EUROCONTROL) traffic control procedures. In the future, 757/767 D926T0120 Web site. Of special interest are when routes and procedures are devel- the Terminal Area RNAV Applications oped to RNP criteria, the regulatory 777 D243W018-7 subgroup and the “EUROCONTROL authority responsible for an airline’s Standard Document for Area Navigation operation will verify that RNP-capable Documents are available at the following Boeing Web site: Equipment— Operational Requirements airplanes meet the RNP requirements http://www.boeing.com/commercial/caft/reference/documents/newdocs.htm and Functional Requirements.” for the operation. This document is available through the document library on the Web site REGIONAL APPROVALS FOR DETAILS ON RNP RETROFITS, CONTACT BOEING AIRPLANE SERVICES. (http://www.ecacnav.com/default.htm). 2 OF RNP OPERATIONS TABLE Phone: 425-865-7950 Software for personal computers. RNP value Type Region Fax: 425-865-7896 flight operation may be subject page displays and scratch-pad text Several software applications are E-mail: [email protected] RNP 4 ICAO Japan to signal availability for both GPS messages, flight crew alerts, and available from vendors of GPS receivers Address: P.O. Box 3707 MC 7R-72 Seattle, WA 98124-2207 USA and ground-based navigation aids navigation displays related to that can help operators determine RNP 5 ICAO Europe (see the following section on RNP RNP and GPS navigation. whether adequate GPS signal coverage FOR ASSISTANCE WITH RNP PROCEDURES, CONTACT BOEING capability documents). is available for an RNP flight operation. RNP 10 ICAO Pacific AIR TRAFFIC MANAGEMENT SERVICES. ■ The availability of different levels Contact the vendors for copies. ■ The minimum equipment required of RNP to satisfy primary and RNP 12.6 ICAO North Atlantic Phone: 206-662-8500 for RNP navigation. supplemental means of navigation. Fax: 206-662-8688 5 OPERATIONAL APPROVALS RNP 0.15 ➔ 0.30 RNP/RNAV Alaska ■ ■ RNP values that provide airplane Example applications of RNP (special approval) E-mail: [email protected] navigation performance equivalent for en route and terminal route RNP operations. RNP operations Address: P.O. Box 3707 MC 29-09 Seattle, WA 98124-2207 USA to traditional airplane navigation separation and approach area gradually are being introduced around Attention: David L. Allen while conducting operations on obstacle clearance. the world on a regional or case-by-case current approaches that do not basis. Operations requiring RNP capa- ■ Discussion of the equivalency require RNP. bilities are noted on the applicable of RNP operations and values to airways and regional airspace docu- ■ Explicit statements of compliance existing charted instrument mentation or procedure charts. These with regional RNP-related criteria. approach procedures approved for operations have varying RNP functional non-RNP RNAV-equipped Boeing and performance requirements. Some airplanes. RNP capability documents. These are more consistent with ICAO RNP, SUMMARY documents explain Boeing RNP imple- ■ Derivation of the demonstrated mini- which allows RNAV-equipped, non-RNP mentation as it relates to equipment mum RNP values listed in the AFM. airplanes to be qualified to a level RNP allows airspace to be specified according to demonstrated airplane navigation certification and RNP operational of RNP equivalency based on originally performance and certain airplane functional capabilities, rather than a required set approvals. They include the following Boeing document for an industry installed equipment, demonstrated (see table 1): RNP RNAV workshop. A Boeing performance, or both. Other operations of navigation sensors or equipment. RNAV functionality is a key element of the RNP require full RNP RNAV functionality. ■ A detailed technical description Web site offers access to the following concept. Knowing in advance that airplanes can perform RNAV functions and achieve Table 2 lists some initial regional of ANP, including ANP values that document on RNP and RNAV opertions: approvals of RNP operations. can be expected, and when GPS “FMS RNAV Workshop—General a predetermined level of navigation performance allows for more optimal design of and GPS coverage predictions may Information on the Functional and RNP RNAV operations. In most cases, airspace and procedures and eliminates the need to mandate specific equipment and be required for an RNP operation. Technical Aspects of Required Navigation Performance (RNP) Area RNP RNAV operations are initiated by systems for airspace operations. RNP functionality exists on all Boeing production ■ Automatic default RNP values and Navigation (RNAV) and Applications” a few operators who have determined phase-of-flight logic. (http://www.boeing.com/commercial/ that their existing airplane RNP RNAV airplanes and is available for retrofit on earlier models. Operators who choose to caft/reference/documents/RNP.pdf). capabilities can provide operating ■ implement RNP can benefit from improved safety of flight in their operations and The concepts of required avail- efficiencies. Achieving RNP RNAV ability of navigation equipment FAA RNP Web site. This site pre- operational approval requires operators access to new, more efficient flight operations procedures. and navigation signals. sents a variety of information on to closely coordinate with all interested ■ Flight crew interface, including existing programs to implement RNP parties, including airspace providers, descriptions of RNP-related CDU (http://www.faa.gov/ats/ato/rnp.htm). regulatory agencies, and flight crew

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