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
ASSOCIATE TECHNICAL FELLOW
RNP 10 ➔ 4
AIR TRAFFIC MANAGEMENT SERVICES
BOEING COMMERCIAL AIRPLANES GROUP

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REQUIRED NAVIGATION PERFORMANCE FOR IMPROVED FLIGHT OPERATIONS

AND EFFICIENT USE OF AIRSPACE
 equired navigation per- beacons. See “Traditional and Area

R
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 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
navigation uncertainty, assurance defined airspace.” This navigation minimum navigation system capabilities.
common navigation parameters normally
of performance through its con- performance accuracy is quantified These additional requirements are
used by industry during equipment design
tainment concepts, and features with two values: a distance in nautical documented in the “Minimum Aviation
and certification. It also lacked a way to
RNP that ensure the repeatability and miles (known as the RNP type) and
statistically specify potential rare excur- System Performance Standards (MASPS):
a probability level. For example, an
predictability of airplane naviga- sions from the desired path. Two aviation Required Navigation Performance for
airplane is qualified to operate on an
tion. This precise characterization RNP 10 airway if it has demonstrated standards organizations —the U.S. Radio Area Navigation,” issued by the RTCA.
of airplane performance is key to that the capability and performance
designing more efficient airspace of the airplane navigation system will
routes and procedures. result in the airplane’s being within
1 ICAO RNP 10 EXAMPLE
FIGURE
Before introducing RNP operations 10 nmi of the indicated position
on the navigation system at least RNP RNP
into their fleets, operators should
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
RNP by the International Civil minimum performance requirement with- 10 nmi
location within 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. intervention capability, traffic density,
10 nmi 10 nmi
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
response, a new tool, called required navigation per-
2 ICAO RNP AIRSPACE BUFFER REDUCTION RNP leads to reduced buffers for route spacing and
increased traffic capacity in the same airspace.
In 1983, the ICAO formed the FIGURE

formance (RNP), is being developed that will be a key Future Air Navigation System (FANS) Navigation performance
Committee to develop a broad strategy POPP
element in reducing en route airplane separation and, that included new methods for airplane
10 nmi
as a result, increase airspace capacity. This tool communication, navigation, and sur-
Pre-RNP RNP
veillance, and air traffic management
defines the navigation accuracy an airplane must have (CNS/ATM) (see “Operator Benefits of
PLMN
to operate within a defined airspace. Ensured naviga- FANS” in Aero no. 2, April 1998). The
tion performance and standardized functionality of navigation element of CNS/ATM centers 60 to 100 nmi
Mitigates navigation errors, Mitigates navigation errors,
on the concept of RNP. RNP provides route structure, traffic
RNP allow new procedures to be designed for airports 5 x RNP, 6 x RNP
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.
Area navigation (RNAV) functionality
flight crews. Boeing has been a leader in developing
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
coordinates and allow for navigation PLWX
Legend:
airplanes in production and in service. on any desired flight path rather than Desired path
RNP 95% threshold
one defined by ground-based radio

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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
of the flight time. This outer linear required performance (i.e., the RNP The MASPS established all signifi-
Defined path
containment region will be used to necessary for the operation). The cant aspects of navigation system
Desired path
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 every MASPS requirement, any system
Minimum navigation system
of RNP is called RNP RNAV to differen- deviations from the MASPS can be
capabilities. In addition to specifying
tiate it from the incomplete specifi- mitigated through limitations or
requirements for continuity and avail-
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
and operations across the fleet. For ■ RNP RNAV is referenced to the for proposed routes and procedures. operations. The Boeing RNP RNAV
example, the types of flight plan legs airplane defined path This will reduce route separation and designs have addressed all the key func-
that could make up RNP route seg- improve obstacle clearance limits tional and performance requirements
■ ICAO RNP is referenced to the of the RNP MASPS. Further MASPS-
ments were limited and standardized beyond those provided by ICAO RNP
airspace desired path compliant changes to Boeing designs
to ensure that all similarly equipped (fig. 4). Benefits include increased
airplanes fly consistent and airspace capacity and efficiency, most likely will be warranted by
operations and the evolution of RNP.
Questions concerning MASPS compliance
for specific models should be directed
4 RNP 4 RNAV EXAMPLE
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
4 nmi management control display unit the message on the CDU, the naviga- airplanes certified for RNP RNAV
8 nmi
(CDU) and the airplane crew alerting tion display, the primary flight display, capability contain some or all of the
4 nmi system. Navigation, flight planning, or a combination of these. following information:
RNP RNP 4 RNAV
PLMN and alerting algorithms are contained
■ The minimum demonstrated RNP
in the airplane flight management
PLMN function (fig. 5). 4 ASSESSING RNP CAPABILITIES as a function of the lateral flight
control mode. This is the smallest
Mitigates navigation Performance The CDU is used for flight plan and Materials and references are available RNP value for which the airplane
4 x RNP
5 x RNP, 6 x RNP errors, route structure, assurance procedure selection and to display the to help operators assess the capabili- equipment has been certified to
(16 nmi)
(20 to 24 nmi) traffic density, surveillance, region 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 communications occurs when the ANP exceeds RNP. On Administration (FAA) RNP Web site, navigate and periods when satel-
Legend:
surveillance or high density. airplanes with crew alerting systems and software for personal computers. lite signals may not be available
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

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 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
FIGURE
for implementing RNP in the U.S. configuration, adjacent route separa- 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
(http://www.ecacnav.com/default.htm). 2 OF RNP OPERATIONS
FOR DETAILS ON RNP RETROFITS, CONTACT BOEING AIRPLANE SERVICES.

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: airplaneservices@boeing.com
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
is available for an RNP flight operation. RNP 10 ICAO Pacific AIR TRAFFIC MANAGEMENT SERVICES.
capability documents).
■ The availability of different levels
Contact the vendors for copies. Phone: 206-662-8500
■ The minimum equipment required of RNP to satisfy primary and RNP 12.6 ICAO North Atlantic
Fax: 206-662-8688
for RNP navigation. supplemental means of navigation.
5 OPERATIONAL APPROVALS RNP 0.15 ➔ 0.30 RNP/RNAV Alaska E-mail: david.l.allen@boeing.com
■ RNP values that provide airplane ■ Example applications of RNP (special approval) Address: P.O. Box 3707 MC 29-09 Seattle, WA 98124-2207 USA
navigation performance equivalent for en route and terminal route RNP operations. RNP operations Attention: David L. Allen
to traditional airplane navigation separation and approach area gradually are being introduced around
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 bilities are noted on the applicable
require RNP.
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
RNP capability documents. These airplanes.
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
Web site offers access to the following require full RNP RNAV functionality.
■ A detailed technical description
Table 2 lists some initial regional
concept. Knowing in advance that airplanes can perform RNAV functions and achieve
of ANP, including ANP values that document on RNP and RNAV opertions:
can be expected, and when GPS “FMS RNAV Workshop—General approvals of RNP operations. a predetermined level of navigation performance allows for more optimal design of
Information on the Functional and
and GPS coverage predictions may
Technical Aspects of Required RNP RNAV operations. In most cases, airspace and procedures and eliminates the need to mandate specific equipment and
be required for an RNP operation.
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
■ The concepts of required avail- efficiencies. Achieving RNP RNAV
implement RNP can benefit from improved safety of flight in their operations and
ability of navigation equipment
and navigation signals.
FAA RNP Web site. This site pre- operational approval requires operators access to new, more efficient flight operations procedures.
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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