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PerformanceBased Navigation (PBN) and Area Navigation (RNAV)
Section 2. PerformanceBased Navigation (PBN) and
Area Navigation (RNAV)
121. General
a. Introduction to PBN. As air travel has
evolved, methods of navigation have improved to
give operators more flexibility. PBN exists under the
umbrella of area navigation (RNAV). The term
RNAV in this context, as in procedure titles, just
means “area navigation,” regardless of the equipment
capability of the aircraft. (See FIG 121.) Many
operators have upgraded their systems to obtain the
benefits of PBN. Within PBN there are two main
categories of navigation methods or specifications:
area navigation (RNAV) and required navigation
performance (RNP). In this context, the term RNAV
x means a specific navigation specification with a
specified lateral accuracy value. For an aircraft to
meet the requirements of PBN, a specified RNAV or
RNP accuracy must be met 95 percent of the flight
time. RNP is a PBN system that includes onboard
performance monitoring and alerting capability (for
example, Receiver Autonomous Integrity Monitor-
ing (RAIM)). PBN also introduces the concept of
navigation specifications (NavSpecs) 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
NavSpecs, 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 detailed in International Civil Aviation
Organization’s (ICAO) Doc 9613, Performance
based Navigation (PBN) Manual and the latest FAA
AC 90105, Approval Guidance for RNP Operations
and Barometric Vertical Navigation in the U.S.
National Airspace System and in Remote and
Oceanic Airspace.
FIG 121
Navigation Specifications
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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 spacebased
navigation aids or within the limits of the capability
of selfcontained 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
groundbased 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 90100, 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
should possess a working knowledge of their aircraft
navigation system to ensure RNAV procedures are
flown in an appropriate manner. In addition, pilots
should have an understanding of the various
waypoint and leg types used in RNAV procedures;
these are discussed in more detail below.
(a) Waypoints. A waypoint is a predeter-
mined geographical position that is defined in terms
of latitude/longitude coordinates. Waypoints may be
a simple named point in space or associated with
existing navaids, intersections, or fixes. A waypoint
is most often used to indicate a change in direction,
speed, or altitude along the desired path. RNAV
procedures make use of both flyover and flyby
waypoints.
(1) Flyby waypoints. Flyby waypoints
are used when an aircraft should begin a turn to the
next course prior to reaching the waypoint separating
the two route segments. This is known as turn
anticipation.
(2) Flyover waypoints. Flyover way-
points are used when the aircraft must fly over the
point prior to starting a turn.
NOTE
FIG 122 illustrates several differences between a flyby
and a flyover waypoint.
FIG 122
Flyby and Flyover Waypoints
(b) RNAV Leg Types. A leg type describes
the desired path proceeding, following, or between
waypoints on an RNAV procedure. Leg types are
identified by a twoletter code that describes the path
(e.g., heading, course, track, etc.) and the termination
point (e.g., the path terminates at an altitude, distance,
fix, etc.). Leg types used for procedure design are
included in the aircraft navigation database, but not
normally provided on the procedure chart. The
narrative depiction of the RNAV chart describes how
a procedure is flown. The “path and terminator
concept” defines that every leg of a procedure has a
termination point and some kind of path into that
termination point. Some of the available leg types are
described below.
(1) Track to Fix. A Track to Fix (TF) leg
is intercepted and acquired as the flight track to the
following waypoint. Track to a Fix legs are
sometimes called pointtopoint legs for this reason.
Narrative: “direct ALPHA, then on course to
BRAVO WP.” See FIG 123.
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PerformanceBased Navigation (PBN) and Area Navigation (RNAV)
(2) Direct to Fix. A Direct to Fix (DF) leg
is a path described by an aircraft’s track from an initial
area direct to the next waypoint. Narrative: “turn
right direct BRAVO WP.” See FIG 124.
FIG 123
Track to Fix Leg Type
FIG 124
Direct to Fix Leg Type
(3) Course to Fix. A Course to Fix (CF)
leg is a path that terminates at a fix with a specified
course at that fix. Narrative: “on course 150 to
ALPHA WP.” See FIG 125.
FIG 125
Course to Fix Leg Type
(4) Radius to Fix. A Radius to Fix (RF)
leg is defined as a constant radius circular path around
a defined turn center that terminates at a fix. See
FIG 126.
FIG 126
Radius to Fix Leg Type
(5) Heading. A Heading leg may be
defined as, but not limited to, a Heading to Altitude
(VA), Heading to DME range (VD), and Heading to
Manual Termination, i.e., Vector (VM). Narra-
tive: climb heading 350 to 1500”, “heading 265, at
9 DME west of PXR VORTAC, right turn heading
360”, “fly heading 090, expect radar vectors to
DRYHT INT.”
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(c) Navigation Issues. Pilots should be
aware of their navigation system inputs, alerts, and
annunciations in order to make betterinformed
decisions. In addition, the availability and suitability
of particular sensors/systems should be considered.
(1) GPS/WAAS. Operators using TSO
C129(), TSOC196(), TSOC145() or TSOC146()
systems should ensure departure and arrival airports
are entered to ensure proper RAIM availability and
CDI sensitivity.
(2) DME/DME. Operators should be
aware that DME/DME position updating is depen-
dent on navigation system logic and DME facility
proximity, availability, geometry, and signal mask-
ing.
(3) VOR/DME. Unique VOR character-
istics may result in less accurate values from
VOR/DME position updating than from GPS or
DME/DME position updating.
(4) Inertial Navigation. Inertial reference
units and inertial navigation systems are often
coupled with other types of navigation inputs,
e.g., DME/DME or GPS, to improve overall
navigation system performance.
NOTE
Specific inertial position updating requirements may
apply.
(d) Flight Management System
(FMS). An FMS is an integrated suite of sensors,
receivers, and computers, coupled with a navigation
database. These systems generally provide perfor-
mance and RNAV guidance to displays and automatic
flight control systems.
Inputs can be accepted from multiple sources such as
GPS, DME, VOR, LOC and IRU. These inputs may
be applied to a navigation solution one at a time or in
combination. Some FMSs provide for the detection
and isolation of faulty navigation information.
When appropriate navigation signals are available,
FMSs will normally rely on GPS and/or DME/DME
(that is, the use of distance information from two or
more DME stations) for position updates. Other
inputs may also be incorporated based on FMS
system architecture and navigation source geometry.
NOTE
DME/DME inputs coupled with one or more IRU(s) are
often abbreviated as DME/DME/IRU or D/D/I.
(e) RNAV Navigation Specifications (Nav
Specs)
Nav Specs 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. (See FIG 121.)
(1) RNAV 1. Typically RNAV 1 is used for
DPs and STARs and appears on the charts. Aircraft
must maintain a total system error of not more than
1 NM for 95 percent of the total flight time.
(2) RNAV 2. Typically RNAV 2 is used for
en route operations unless otherwise specified.
T-routes and Q-routes are examples of this Nav Spec.
Aircraft must maintain a total system error of not
more than 2 NM for 95 percent of the total flight time.
(3) RNAV 10. Typically RNAV 10 is used
in oceanic operations. See paragraph 471 for
specifics and explanation of the relationship between
RNP 10 and RNAV 10 terminology.
122. Required Navigation Performance
(RNP)
a. General. While both RNAV navigation speci-
fications (NavSpecs) and RNP NavSpecs contain
specific performance requirements, RNP is RNAV
with the added requirement for onboard performance
monitoring and alerting (OBPMA). RNP is also a
statement of navigation performance necessary for
operation within a defined airspace. A critical
component of RNP is the ability of the aircraft
navigation system to monitor its achieved navigation
performance, and to identify for the pilot whether the
operational requirement is, or is not, being met during
an operation. OBPMA capability therefore allows a
lessened reliance on air traffic control intervention
and/or procedural separation to achieve the overall
safety of the operation. RNP capability of the aircraft
is a major component in determining the separation
criteria to ensure that the overall containment of the
operation is met. The RNP capability of an aircraft
will vary depending upon the aircraft equipment and
the navigation infrastructure. For example, an aircraft
may be eligible for RNP 1, but may not be capable of
RNP 1 operations due to limited NAVAID coverage
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PerformanceBased Navigation (PBN) and Area Navigation (RNAV)
or avionics failure. The Aircraft Flight Manual
(AFM) or avionics documents for your aircraft
should specifically state the aircraft’s RNP eligibili-
ties. Contact the manufacturer of the avionics or the
aircraft if this information is missing or incomplete.
NavSpecs should be considered different from one
another, not “better” or “worse” based on the
described lateral navigation accuracy. It is this
concept that requires each NavSpec eligbility to be
listed separately in the avionics documents or AFM.
For example, RNP 1 is different from RNAV 1, and
an RNP 1 eligibility does NOT mean automatic RNP
2 or RNAV 1 eligibility. As a safeguard, the FAA
requires that aircraft navigation databases hold only
those procedures that the aircraft maintains eligibility
for. If you look for a specific instrument procedure in
your aircraft’s navigation database and cannot find it,
it’s likely that procedure contains PBN elements your
aircraft is ineligible for or cannot compute and fly.
Further, optional capabilities such as Radiustofix
(RF) turns or scalability should be described in the
AFM or avionics documents. Use the capabilities of
your avionics suite to verify the appropriate waypoint
and track data after loading the procedure from your
database.
b. PBN Operations.
1. Lateral Accuracy Values. Lateral Accuracy
values are applicable to a selected airspace, route, or
procedure. The lateral accuracy value is a value
typically expressed as a distance in nautical miles
from the intended centerline of a procedure, route, or
path. RNP applications also account for potential
errors at some multiple of lateral accuracy value (for
example, twice the RNP lateral accuracy values).
(a) RNP NavSpecs. U.S. standard NavSpecs
supporting typical RNP airspace uses are as specified
below. Other NavSpecs may include different lateral
accuracy values as identified by ICAO or other states.
(See FIG 121.)
(1) RNP Approach (RNP APCH). In the
U.S., RNP APCH procedures are titled RNAV (GPS)
and offer several lines of minima to accommodate
varying levels of aircraft equipage: either lateral
navigation (LNAV), LNAV/vertical navigation
(LNAV/VNAV), Localizer Performance with Verti-
cal Guidance (LPV), and Localizer Performance
(LP). GPS with or without SpaceBased Augmenta-
tion System (SBAS) (for example, WAAS) can
provide the lateral information to support LNAV
minima. LNAV/VNAV incorporates LNAV lateral
with vertical path guidance for systems and operators
capable of either barometric or SBAS vertical. Pilots
are required to use SBAS to fly to the LPV or LP
minima. RF turn capability is optional in RNP APCH
eligibility. This means that your aircraft may be
eligible for RNP APCH operations, but you may not
fly an RF turn unless RF turns are also specifically
listed as a feature of your avionics suite. GBAS
Landing System (GLS) procedures are also con-
structed using RNP APCH NavSpecs and provide
precision approach capability. RNP APCH has a
lateral accuracy value of 1 in the terminal and missed
approach segments and essentially scales to RNP 0.3
(or 40 meters with SBAS) in the final approach. (See
Paragraph 5418, RNP AR Instrument Approach
Procedures.)
(2) RNP Authorization Required Ap-
proach (RNP AR APCH). In the U.S., RNP AR
APCH procedures are titled RNAV (RNP). These
approaches have stringent equipage and pilot training
standards and require special FAA authorization to
fly. Scalability and RF turn capabilities are
mandatory in RNP AR APCH eligibility. RNP AR
APCH vertical navigation performance is based upon
barometric VNAV or SBAS. RNP AR is intended to
provide specific benefits at specific locations. It is not
intended for every operator or aircraft. RNP AR
capability requires specific aircraft performance,
design, operational processes, training, and specific
procedure design criteria to achieve the required
target level of safety. RNP AR APCH has lateral
accuracy values that can range below 1 in the terminal
and missed approach segments and essentially scale
to RNP 0.3 or lower in the final approach. Before
conducting these procedures, operators should refer
to the latest AC 90101, Approval Guidance for RNP
Procedures with AR. (See paragraph 5418.)
(3) RNP Authorization Required Depar-
ture (RNP AR DP). Similar to RNP AR approaches,
RNP AR departure procedures have stringent
equipage and pilot training standards and require
special FAA authorization to fly. Scalability and RF
turn capabilities is mandatory in RNP AR DP
eligibility. RNP AR DP is intended to provide
specific benefits at specific locations. It is not
intended for every operator or aircraft. RNP AR DP
capability requires specific aircraft performance,
design, operational processes, training, and specific
procedure design criteria to achieve the required
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target level of safety. RNP AR DP has lateral
accuracy values that can scale to no lower than RNP
0.3 in the initial departure flight path. Before
conducting these procedures, operators should refer
to the latest AC 90101, Approval Guidance for RNP
Procedures with AR. (See paragraph 5418.)
(4) Advanced RNP (ARNP). Advanced
RNP is a NavSpec with a minimum set of mandatory
functions enabled in the aircraft’s avionics suite. In
the U.S., these minimum functions include capability
to calculate and perform RF turns, scalable RNP, and
parallel offset flight path generation. Higher
continuity (such as dual systems) may be required for
certain oceanic and remote continental airspace.
Other “advanced” options for use in the en route
environment (such as fixed radius transitions and
Time of Arrival Control) are optional in the U.S.
Typically, an aircraft eligible for ARNP will also be
eligible for operations comprising: RNP APCH,
RNP/RNAV 1, RNP/RNAV 2, RNP 4, and
RNP/RNAV 10. ARNP allows for scalable RNP
lateral navigation values (either 1.0 or 0.3) in the
terminal environment. Use of these reduced lateral
accuracies will normally require use of the aircraft’s
autopilot and/or flight director. See the latest AC
90105 for more information on ARNP, including
NavSpec bundling options, eligibility determina-
tions, and operations approvals.
NOTE
ARNP eligible aircraft are NOT automatically eligible for
RNP AR APCH or RNP AR DP operations, as RNP AR
eligibility requires a separate determination process and
special FAA authorization.
(5) RNP 1. RNP 1 requires a lateral
accuracy value of 1 for arrival and departure in the
terminal area, and the initial and intermediate
approach phase when used on conventional proce-
dures with PBN segments (for example, an ILS with
a PBN feeder, IAF, or missed approach). RF turn
capability is optional in RNP 1 eligibility. This means
that your aircraft may be eligible for RNP 1
operations, but you may not fly an RF turn unless RF
turns are also specifically listed as a feature of your
avionics suite.
(6) RNP 2. RNP 2 will apply to both
domestic and oceanic/remote operations with a
lateral accuracy value of 2.
(7) RNP 4. RNP 4 will apply to oceanic and
remote operations only with a lateral accuracy value
of 4. RNP 4 eligibility will automatically confer
RNP 10 eligibility.
(8) RNP 10. The RNP 10 NavSpec applies
to certain oceanic and remote operations with a lateral
accuracy of 10. In such airspace, the RNAV 10
NavSpec will be applied, so any aircraft eligible for
RNP 10 will be deemed eligible for RNAV 10
operations. Further, any aircraft eligible for RNP 4
operations is automatically qualified for RNP 10/
RNAV 10 operations. (See also the latest AC 9170,
Oceanic and Remote Continental Airspace Opera-
tions, for more information on oceanic RNP/RNAV
operations.)
(9) RNP 0.3. The RNP 0.3 NavSpec
requires a lateral accuracy value of 0.3 for all
authorized phases of flight. RNP 0.3 is not authorized
for oceanic, remote, or the final approach segment.
Use of RNP 0.3 by slowflying fixedwing aircraft is
under consideration, but the RNP 0.3 NavSpec
initially will apply only to rotorcraft operations. RF
turn capability is optional in RNP 0.3 eligibility. This
means that your aircraft may be eligible for RNP 0.3
operations, but you may not fly an RF turn unless RF
turns are also specifically listed as a feature of your
avionics suite.
NOTE
On terminal procedures or en route charts, do not confuse
a charted RNP value of 0.30, or any standard final
approach course segment width of 0.30, with the NavSpec
title “RNP 0.3.” Charted RNP values of 0.30 or below
should contain two decimal places (for example, RNP 0.15,
or 0.10, or 0.30) whereas the NavSpec title will only state
“RNP 0.3.”
(b) Application of Standard Lateral Accu-
racy Values. U.S. standard lateral accuracy values
typically used for various routes and procedures
supporting RNAV operations may be based on use of
a specific navigational system or sensor such as GPS,
or on multisensor RNAV systems having suitable
performance.
(c) Depiction of PBN Requirements. In the
U.S., PBN requirements like Lateral Accuracy
Values or NavSpecs applicable to a procedure will be
depicted on affected charts and procedures. In the
U.S., a specific procedure’s PerformanceBased
Navigation (PBN) requirements will be prominently
displayed in separate, standardized notes boxes. For
procedures with PBN elements, the “PBN box” will
contain the procedure’s NavSpec(s); and, if required:
specific sensors or infrastructure needed for the
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navigation solution, any additional or advanced
functional requirements, the minimum RNP value,
and any amplifying remarks. Items listed in this PBN
box are REQUIRED to fly the procedure’s PBN
elements. For example, an ILS with an RNAV missed
approach would require a specific capability to fly the
missed approach portion of the procedure. That
required capability will be listed in the PBN box. The
separate Equipment Requirements box will list
groundbased equipment and/or airport specific
requirements. On procedures with both PBN
elements and groundbased equipment require-
ments, the PBN requirements box will be listed first.
(See FIG 541.)
c. Other RNP Applications Outside the U.S.
The FAA and ICAO member states have led
initiatives in implementing the RNP concept to
oceanic operations. For example, RNP10 routes
have been established in the northern Pacific
(NOPAC) which has increased capacity and
efficiency by reducing the distance between tracks
to 50 NM. (See paragraph 471.)
d. Aircraft and Airborne Equipment Eligibility
for RNP Operations. Aircraft eligible for RNP
operations will have an appropriate entry including
special conditions and limitations in its AFM,
avionics manual, or a supplement. Operators of
aircraft not having specific RNP eligibility state-
ments in the AFM or avionics documents may be
issued operational approval including special condi-
tions and limitations for specific RNP eligibilities.
NOTE
Some airborne systems use Estimated Position Uncertain-
ty (EPU) as a measure of the current estimated
navigational performance. EPU may also be referred to as
Actual Navigation Performance (ANP) or Estimated
Position Error (EPE).
TBL 121
U.S. Standard RNP Levels
RNP Level
Typical Application Primary Route
Width (NM)
Centerline to
Boundary
0.1 to 1.0 RNP AR Approach Segments 0.1 to 1.0
0.3 to 1.0 RNP Approach Segments 0.3 to 1.0
1 Terminal and En Route 1.0
2 En Route 2.0
4 Projected for oceanic/remote areas where 30 NM horizontal
separation is applied.
4.0
10 Oceanic/remote areas where 50 NM lateral separation is
applied.
10.0
123. Use of Suitable Area Navigation
(RNAV) Systems on Conventional
Procedures and Routes
a. Discussion. This paragraph sets forth policy,
while providing operational and airworthiness
guidance regarding the suitability and use of RNAV
systems when operating on, or transitioning to,
conventional, nonRNAV routes and procedures
within the U.S. National Airspace System (NAS):
1. Use of a suitable RNAV system as a
Substitute Means of Navigation when a VeryHigh
Frequency (VHF) Omnidirectional Range (VOR),
Distance Measuring Equipment (DME), Tactical Air
Navigation (TACAN), VOR/TACAN (VORTAC),
VOR/DME, Nondirectional Beacon (NDB), or
compass locator facility including locator outer
marker and locator middle marker is outofservice
(that is, the navigation aid (NAVAID) information is
not available); an aircraft is not equipped with an
Automatic Direction Finder (ADF) or DME; or the
installed ADF or DME on an aircraft is not
operational. For example, if equipped with a suitable
RNAV system, a pilot may hold over an outofser-
vice NDB.
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2. Use of a suitable RNAV system as an
Alternate Means of Navigation when a VOR, DME,
VORTAC, VOR/DME, TACAN, NDB, or compass
locator facility including locator outer marker and
locator middle marker is operational and the
respective aircraft is equipped with operational
navigation equipment that is compatible with
conventional navaids. For example, if equipped with
a suitable RNAV system, a pilot may fly a procedure
or route based on operational VOR using that RNAV
system without monitoring the VOR.
NOTE
1. Additional information and associated requirements
are available in Advisory Circular 90-108 titled “Use of
Suitable RNAV Systems on Conventional Routes and
Procedures.”
2. Good planning and knowledge of your RNAV system are
critical for safe and successful operations.
3. Pilots planning to use their RNAV system as a substitute
means of navigation guidance in lieu of an outofservice
NAVAID may need to advise ATC of this intent and
capability.
4. The navigation database should be current for the
duration of the flight. If the AIRAC cycle will change
during flight, operators and pilots should establish
procedures to ensure the accuracy of navigation data,
including suitability of navigation facilities used to define
the routes and procedures for flight. To facilitate validating
database currency, the FAA has developed procedures for
publishing the amendment date that instrument approach
procedures were last revised. The amendment date follows
the amendment number, e.g., Amdt 4 14Jan10. Currency of
graphic departure procedures and STARs may be
ascertained by the numerical designation in the procedure
title. If an amended chart is published for the procedure, or
the procedure amendment date shown on the chart is on or
after the expiration date of the database, the operator must
not use the database to conduct the operation.
b. Types of RNAV Systems that Qualify as a
Suitable RNAV System. When installed in accor-
dance with appropriate airworthiness installation
requirements and operated in accordance with
applicable operational guidance (for example,
aircraft flight manual and Advisory Circular
material), the following systems qualify as a suitable
RNAV system:
1. An RNAV system with TSOC129/
C145/C146 equipment, installed in accordance
with AC 20138, Airworthiness Approval of Global
Positioning System (GPS) Navigation Equipment for
Use as a VFR and IFR Supplemental Navigation
System, and authorized for instrument flight rules
(IFR) en route and terminal operations (including
those systems previously qualified for “GPS in lieu of
ADF or DME” operations), or
2. An RNAV system with DME/DME/IRU
inputs that is compliant with the equipment
provisions of AC 90100A, U.S. Terminal and
En Route Area Navigation (RNAV) Operations, for
RNAV routes. A table of compliant equipment is
available at the following website:
https://www.faa.gov/about/office_org/headquart
ers_offices/avs/offices/afx/afs/afs400/afs410/medi
a/AC90100compliance.pdf
NOTE
Approved RNAV systems using DME/DME/IRU, without
GPS/WAAS position input, may only be used as a substitute
means of navigation when specifically authorized by a
Notice to Airmen (NOTAM) or other FAA guidance for a
specific procedure. The NOTAM or other FAA guidance
authorizing the use of DME/DME/IRU systems will also
identify any required DME facilities based on an FAA
assessment of the DME navigation infrastructure.
c. Uses of Suitable RNAV Systems. Subject to
the operating requirements, operators may use a
suitable RNAV system in the following ways.
1. Determine aircraft position relative to, or
distance from a VOR (see NOTE 6 below), TACAN,
NDB, compass locator, DME fix; or a named fix
defined by a VOR radial, TACAN course, NDB
bearing, or compass locator bearing intersecting a
VOR or localizer course.
2. Navigate to or from a VOR, TACAN, NDB,
or compass locator.
3. Hold over a VOR, TACAN, NDB, compass
locator, or DME fix.
4. Fly an arc based upon DME.
NOTE
1. The allowances described in this section apply even
when a facility is identified as required on a procedure (for
example, “Note ADF required”).
2. These operations do not include lateral navigation on
localizerbased courses (including localizer backcourse
guidance) without reference to raw localizer data.
3. Unless otherwise specified, a suitable RNAV system
cannot be used for navigation on procedures that are
identified as not authorized (“NA”) without exception by
a NOTAM. For example, an operator may not use a RNAV
system to navigate on a procedure affected by an expired or
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unsatisfactory flight inspection, or a procedure that is
based upon a recently decommissioned NAVAID.
4. Pilots may not substitute for the NAVAID (for example,
a VOR or NDB) providing lateral guidance for the final
approach segment. This restriction does not refer to
instrument approach procedures with “or GPS” in the title
when using GPS or WAAS. These allowances do not apply
to procedures that are identified as not authorized (NA)
without exception by a NOTAM, as other conditions may
still exist and result in a procedure not being available. For
example, these allowances do not apply to a procedure
associated with an expired or unsatisfactory flight
inspection, or is based upon a recently decommissioned
NAVAID.
5. Use of a suitable RNAV system as a means to navigate
on the final approach segment of an instrument approach
procedure based on a VOR, TACAN or NDB signal, is
allowable. The underlying NAVAID must be operational
and the NAVAID monitored for final segment course
alignment.
6. For the purpose of paragraph c, “VOR” includes VOR,
VOR/DME, and VORTAC facilities and “compass
locator” includes locator outer marker and locator middle
marker.
d. Alternate Airport Considerations. For the
purposes of flight planning, any required alternate
airport must have an available instrument approach
procedure that does not require the use of GPS. This
restriction includes conducting a conventional
approach at the alternate airport using a substitute
means of navigation that is based upon the use of
GPS. For example, these restrictions would apply
when planning to use GPS equipment as a substitute
means of navigation for an outofservice VOR that
supports an ILS missed approach procedure at an
alternate airport. In this case, some other approach
not reliant upon the use of GPS must be available.
This restriction does not apply to RNAV systems
using TSOC145/C146 WAAS equipment. For
further WAAS guidance, see paragraph 1118.
1. For flight planning purposes, TSO-C129()
and TSO-C196() equipped users (GPS users) whose
navigation systems have fault detection and
exclusion (FDE) capability, who perform a preflight
RAIM prediction at the airport where the RNAV
(GPS) approach will be flown, and have proper
knowledge and any required training and/or approval
to conduct a GPS-based IAP, may file based on a
GPS-based IAP at either the destination or the
alternate airport, but not at both locations. At the
alternate airport, pilots may plan for applicable
alternate airport weather minimums using:
(a) Lateral navigation (LNAV) or circling
minimum descent altitude (MDA);
(b) LNAV/vertical navigation (LNAV/
VNAV) DA, if equipped with and using approved
barometric vertical navigation (baro-VNAV) equip-
ment;
(c) RNP 0.3 DA on an RNAV (RNP) IAP, if
they are specifically authorized users using approved
baro-VNAV equipment and the pilot has verified
required navigation performance (RNP) availability
through an approved prediction program.
2. If the above conditions cannot be met, any
required alternate airport must have an approved
instrument approach procedure other than GPS that is
anticipated to be operational and available at the
estimated time of arrival, and which the aircraft is
equipped to fly.
3. This restriction does not apply to
TSO-C145() and TSO-C146() equipped users
(WAAS users). For further WAAS guidance, see
paragraph 1118.
124. Pilots and Air Traffic Controllers
Recognizing Interference or Spoofing
a. Pilots need to maintain position awareness
while navigating. This awareness may be facilitated
by keeping relevant groundbased, legacy naviga-
tional aids tuned and available. By utilizing this
practice, situational awareness is promoted and
guards against significant pilot delay in recognizing
the onset of GPS interference. Pilots may find
crosschecks of other airborne systems (for example,
DME/DME/IRU or VOR) useful to mitigate this
otherwise undetected hazard.
REFERENCE
AIM Paragraph 1117, Global Positioning System (GPS)
AIM Paragraph 1118, Wide Area Augmentation System (WAAS)
b. During preflight planning, pilots should be
particularly alert for NOTAMs which could affect
navigation (GPS or WAAS) along their route of
flight, such as Department of Defense electronic
signal tests with GPS.
REFERENCE
AIM Paragraph 1117, Global Positioning System (GPS)
AIM Paragraph 1118, Wide Area Augmentation System (WAAS)
c. If the pilot experiences interruptions while
navigating with GPS, the pilot and ATC may both
AIM 8/15/19
1210
PerformanceBased Navigation (PBN) and Area Navigation (RNAV)
incur a higher workload. In the aircraft, the pilot may
need to change to a position determining method that
does not require GPSderived signals (for example,
DME/DME/IRU or VOR). If transitioning to VOR
navigation, the pilot should refer to the current Chart
Supplement U.S. to identify airports with available
conventional approaches associated with the VOR
Minimum Operational Network (MON) program. If
the pilot’s aircraft is under ATC radar or multilatera-
tion surveillance, ATC may be able to provide radar
vectors out of the interference affected area or to an
alternate destination upon pilot request. An ADSB
Out aircraft’s broadcast information may be incorrect
and should not be relied upon for surveillance when
interference or spoofing is suspected unless its
accuracy can be verified by independent means.
During the approach phase, a pilot might elect to
continue in visual conditions or may need to execute
the published missed approach. If the published
missed approach procedure is GPSbased, the pilot
will need alternate instructions. If the pilot were to
choose to continue in visual conditions, the pilot
could aid the controller by cancelling his/her IFR
flight plan and proceeding visually to the airport to
land. ATC would cancel the pilot’s IFR clearance and
issue a VFR squawk; freeing up the controller to
handle other aircraft.
d. The FAA requests that pilots notify ATC if they
experience interruptions to their GPS navigation or
surveillance. GPS interference or outages associated
with a known testing NOTAM should not be reported
to ATC unless the interference/outage affects the
pilot’s ability to navigate his/her aircraft.
REFERENCE
AIM Paragraph 1113, User Reports Requested on NAVAID or Global
Navigation Satellite System (GNSS) Performance or Interference.