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AIM

10/12/17

1−2−1

Performance−Based Navigation (PBN) and Area Navigation (RNAV)

Section 2. Performance−Based Navigation (PBN) and

Area Navigation (RNAV)

1−2−1. General

a. Introduction to PBN. As air travel has

evolved, methods of navigation have improved to

give operators more flexibility. Under the umbrella of

area navigation, there are legacy and performance−

based navigation (PBN) methods, see FIG 1−2−1.

The legacy methods include operations incorporating

systems approved under AC 90-45, Approval of Area

Navigation Systems for Use in the U.S. National

Airspace System, which allows two-dimensional

area navigation (2D RNAV) within the U.S. National

Airspace System (NAS). AC 90-45 describes 2D

RNAV in terms of both VOR/DME dependent

systems and self-contained systems such as Inertial

Navigation Systems (INS). Many operators have

upgraded their systems to obtain the benefits of PBN.

Within PBN there are two main categories of

navigation methods: area navigation (RNAV) and

required navigation performance (RNP). For an

aircraft to meet the requirements of RNAV, a

specified RNAV accuracy must be met 95 percent of

the flight time. RNP is an RNAV system that includes

onboard performance monitoring and alerting

capability (for example, Receiver Autonomous

Integrity Monitoring (RAIM)). PBN also introduces

the concept of navigation specifications (Nav Specs)

which are a set of aircraft and aircrew requirements

needed to support a navigation application within a

defined airspace concept. For both RNP and RNAV

designations, the numerical designation refers to the

lateral navigation accuracy in nautical miles which is

expected to be achieved at least 95 percent of the

flight time by the population of aircraft operating

within the airspace, route, or procedure. This

information is introduced in International Civil

Aviation Organization’s (ICAO) Doc 9613, Perform-

ance-based Navigation (PBN) Manual (Fourth

Edition, 2013) and the FAA AC 90-105A, Approval

Guidance for RNP Operations and Barometric

Vertical Navigation in the U.S. National Airspace

System and in Remote and Oceanic Airspace

(expected publication date in late 2014) further

develops this story.

FIG 1−2−1

b. Area Navigation (RNAV)

1. General.  RNAV is a method of navigation

that permits aircraft operation on any desired flight

path within the coverage of ground− or space−based

navigation aids or within the limits of the capability

of self−contained aids, or a combination of these. In

the future, there will be an increased dependence on

the use of RNAV in lieu of routes defined by

ground−based navigation aids. RNAV routes and

terminal procedures, including departure procedures

(DPs) and standard terminal arrivals (STARs), are

designed with RNAV systems in mind. There are

several potential advantages of RNAV routes and

procedures:

(a) Time and fuel savings;
(b) Reduced dependence on radar vectoring,

altitude, and speed assignments allowing a reduction

in required ATC radio transmissions; and

(c) More efficient use of airspace.

In addition to information found in this manual,

guidance for domestic RNAV DPs, STARs, and

routes may also be found in AC 90−100, U.S.

Terminal and En Route Area Navigation (RNAV)

Operations.

2. RNAV Operations. RNAV procedures, such

as DPs and STARs, demand strict pilot awareness and

maintenance of the procedure centerline. Pilots