6. A new method has been added for selecting
the final approach segment of an instrument
approach. Along with the current method used by
most receivers using menus where the pilot selects the
airport, the runway, the specific approach procedure
and finally the IAF, there is also a channel number
selection method. The pilot enters a unique 5-digit
number provided on the approach chart, and the
receiver recalls the matching final approach segment
from the aircraft database. A list of information
including the available IAFs is displayed and the pilot
selects the appropriate IAF. The pilot should confirm
that the correct final approach segment was loaded by
cross checking the Approach ID, which is also
provided on the approach chart.
7. The Along-Track Distance (ATD) during the
final approach segment of an LNAV procedure (with
a minimum descent altitude) will be to the MAWP. On
LNAV/VNAV and LPV approaches to a decision
altitude, there is no missed approach waypoint so the
along-track distance is displayed to a point normally
located at the runway threshold. In most cases the
MAWP for the LNAV approach is located on the
runway threshold at the centerline, so these distances
will be the same. This distance will always vary
slightly from any ILS DME that may be present, since
the ILS DME is located further down the runway.
Initiation of the missed approach on the LNAV/
VNAV and LPV approaches is still based on reaching
the decision altitude without any of the items listed in
14 CFR Section 91.175 being visible, and must not be
delayed until the ATD reaches zero. The WAAS
receiver, unlike a GPS receiver, will automatically
sequence past the MAWP if the missed approach
procedure has been designed for RNAV. The pilot
may also select missed approach prior to the MAWP,
however, navigation will continue to the MAWP prior
to waypoint sequencing taking place.
1-1-21. GNSS Landing System (GLS)
a. General
1. The GLS provides precision navigation
guidance for exact alignment and descent of aircraft
on approach to a runway. It provides differential
augmentation to the Global Navigation Satellite
System (GNSS).
2. The U.S. plans to provide augmentation
services to the GPS for the first phase of GNSS. This
section will be revised and updated to reflect
international standards and GLS services as they are
provided.
1-1-22. Precision Approach Systems other
than ILS, GLS, and MLS
a. General
Approval and use of precision approach systems
other than ILS, GLS and MLS require the issuance of
special instrument approach procedures.
3/15/07 7110.65R CHG 2 AIM 7/31/08
AIM 2/14/08
1-1-41
Navigation Aids
b. Special Instrument Approach Procedure
1. Special instrument approach procedures
must be issued to the aircraft operator if pilot training,
aircraft equipment, and/or aircraft performance is
different than published procedures. Special instrument approach procedures are not distributed for
general public use. These procedures are issued to an
aircraft operator when the conditions for operations
approval are satisfied.
2. General aviation operators requesting approval for special procedures should contact the local
Flight Standards District Office to obtain a letter of
authorization. Air carrier operators requesting
approval for use of special procedures should contact
their Certificate Holding District Office for authorization through their Operations Specification.
c. Transponder Landing System (TLS)
1. The TLS is designed to provide approach
guidance utilizing existing airborne ILS localizer,
glide slope, and transponder equipment.
2. Ground equipment consists of a transponder
interrogator, sensor arrays to detect lateral and
vertical position, and ILS frequency transmitters. The
TLS detects the aircraft’s position by interrogating its
transponder. It then broadcasts ILS frequency signals
to guide the aircraft along the desired approach path.
3. TLS instrument approach procedures are
designated Special Instrument Approach Procedures.
Special aircrew training is required. TLS ground
equipment provides approach guidance for only one
aircraft at a time. Even though the TLS signal is
received using the ILS receiver, no fixed course or
glidepath is generated. The concept of operation is
very similar to an air traffic controller providing radar
vectors, and just as with radar vectors, the guidance
is valid only for the intended aircraft. The TLS
ground equipment tracks one aircraft, based on its
transponder code, and provides correction signals to
course and glidepath based on the position of the
tracked aircraft. Flying the TLS corrections computed for another aircraft will not provide guidance
relative to the approach; therefore, aircrews must not
use the TLS signal for navigation unless they have
received approach clearance and completed the
required coordination with the TLS ground equipment operator. Navigation fixes based on
conventional NAVAIDs or GPS are provided in the
special instrument approach procedure to allow
aircrews to verify the TLS guidance.
d. Special Category I Differential GPS
(SCAT-I DGPS)
1. The SCAT-I DGPS is designed to provide
approach guidance by broadcasting differential
correction to GPS.
2. SCAT-I DGPS procedures require aircraft
equipment and pilot training.
3. Ground equipment consists of GPS receivers
and a VHF digital radio transmitter. The SCAT-I
DGPS detects the position of GPS satellites relative
to GPS receiver equipment and broadcasts differential corrections over the VHF digital radio.
4. Category I Ground Based Augmentation
System (GBAS) will displace SCAT-I DGPS as the
public use service.
REFERENCE-
AIM, Para 5-4-7f, Instrument Approach Procedures.
7/31/08 AIM
AIM 2/14/08
1-2-1
Area Navigation (RNAV) and Required Navigation Performance (RNP)
Section 2. Area Navigation (RNAV) and Required
Navigation Performance (RNP)
1-2-1. Area Navigation (RNAV)
a. General. RNAV is a method of navigation that
permits aircraft operation on any desired flight path
within the coverage of station-referenced 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:
1. Time and fuel savings,
2. Reduced dependence on radar vectoring,
altitude, and speed assignments allowing a reduction
in required ATC radio transmissions, and
3. 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 Advisory Circu-
lar_90-100, U.S. Terminal and En Route Area
Navigation (RNAV) Operations.
b. 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.
1. Waypoints. A waypoint is a predetermined
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 fly-over and fly-by
waypoints.
(a) Fly-by waypoints. Fly-by 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.
(b) Fly-over waypoints. Fly-over way-
points are used when the aircraft must fly over the
point prior to starting a turn.
NOTE-
FIG 1-2-1 illustrates several differences between a fly-by
and a fly-over waypoint.
FIG 1-2-1
Fly-by and Fly-over Waypoints
2. 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 two-letter 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.
AIM 2/14/08
1-2-2 Area Navigation (RNAV) and Required Navigation Performance (RNP)
(a) 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 point-to-point legs for this reason.
Narrative: “via 087_ track to CHEZZ WP.” See
FIG 1-2-2.
(b) 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: “left
turn direct BARGN WP.” See FIG 1-2-3.
FIG 1-2-2
Track to Fix Leg Type
FIG 1-2-3
Direct to Fix Leg Type
AIM 2/14/08
1-2-3
Area Navigation (RNAV) and Required Navigation Performance (RNP)
(c) 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: “via 078_ course to PRIMY
WP.” See FIG 1-2-4.
FIG 1-2-4
Course to Fix Leg Type
(d) 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 1-2-5.
FIG 1-2-5
Radius to Fix Leg Type
(e) 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). Narrative: “climb
runway heading to 1500”, “heading 265_, at 9 DME
west of PXR VORTAC, right turn heading 360_”, “fly
heading 090_, expect radar vectors to DRYHT INT.”
3. Navigation Issues. Pilots should be aware
of their navigation system inputs, alerts, and
annunciations in order to make better-informed
decisions. In addition, the availability and suitability
of particular sensors/systems should be considered.
(a) GPS. Operators using TSO-C129 sys-
tems should ensure departure and arrival airports are
entered to ensure proper RAIM availability and CDI
sensitivity.
(b) DME/DME. Operators should be aware
that DME/DME position updating is dependent on
FMS logic and DME facility proximity, availability,
geometry, and signal masking.
(c) VOR/DME. Unique VOR characteris-
tics may result in less accurate values from
VOR/DME position updating than from GPS or
DME/DME position updating.
(d) 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.
4. Flight Management System (FMS). An
FMS is an integrated suite of sensors, receivers, and
computers, coupled with a navigation database.
These systems generally provide performance 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.
AIM 2/14/08
1-2-4 Area Navigation (RNAV) and Required Navigation Performance (RNP)
1-2-2. Required Navigation Performance
(RNP)
a. General. RNP is RNAV with on-board
navigation monitoring and alerting, 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. This on-board performance monitor-
ing and alerting capability therefore allows a lessened
reliance on air traffic control intervention (via radar
monitoring, automatic dependent surveillance
(ADS), multilateration, communications), and/or
route 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
equipped and certified for RNP 1.0, but may not be
capable of RNP 1.0 operations due to limited navaid
coverage.
b. RNP Operations.
1. RNP Levels. An RNP “level” or “type” is
applicable to a selected airspace, route, or procedure.
ICAO has defined RNP values for the four typical
navigation phases of flight: oceanic, en route,
terminal, and approach. As defined in the Pilot/
Controller Glossary, the RNP Level or Type 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 RNP level (e.g., twice the
RNP level).
(a) Standard RNP Levels. U.S. standard
values supporting typical RNP airspace are as
specified in TBL 1-2-1 below. Other RNP levels as
identified by ICAO, other states and the FAA may
also be used.
(b) Application of Standard RNP Levels.
U.S. standard levels of RNP 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
multi-sensor RNAV systems having suitable perfor-
mance.
(c) Depiction of Standard RNP Levels. The
applicable RNP level will be depicted on affected
charts and procedures.
TBL 1-2-1
U.S. Standard RNP Levels
RNP Level Typical Application Primary Route Width (NM) -
Centerline to Boundary
0.1 to 1.0 RNP SAAAR 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
NOTE1. The “performance” of navigation in RNP refers not only to the level of accuracy of a particular sensor or aircraft
navigation system, but also to the degree of precision with which the aircraft will be flown.
2. Specific required flight procedures may vary for different RNP levels.
AIM 2/14/08
1-2-5
Area Navigation (RNAV) and Required Navigation Performance (RNP)
TBL 1-2-2
RNP Levels Supported for International Operations
RNP Level Typical Application
4 Projected for oceanic/remote areas where 30 NM horizontal separation is applied
10 Oceanic/remote areas where 50 NM lateral separation is applied
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, RNP-10 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 TBL 1-2-2.)
d. Aircraft and Airborne Equipment Eligibility
for RNP Operations. Aircraft meeting RNP criteria
will have an appropriate entry including special
conditions and limitations in its Aircraft Flight
Manual (AFM), or supplement. Operators of aircraft
not having specific AFM-RNP certification may be
issued operational approval including special conditions and limitations for specific RNP levels.
NOTE-
Some airborne systems use Estimated Position Uncertainty (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).
1-2-3. Use of Suitable Area Navigation
(RNAV) Systems on Conventional
Procedures and Routes
a. Discussion. This paragraph sets forth policy
concerning the operational use of RNAV systems for
the following applications within the U.S. National
Airspace System (NAS):
1. When a very-high frequency omni-
directional range (VOR), DME, tactical air
navigation (TACAN), VORTAC, VOR/DME, nondirectional beacon (NDB), or compass locator
facility including locator outer marker and locator
middle marker is out-of-service (that is, the
navigation aid (navaid) information is not available);
an aircraft is not equipped with an 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 out-of-
service NDB. This category of use is referred to as
“substitute means of navigation.”
2. 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 RNAV equipment but not monitor the VOR.
This category of use is referred to as “alternate means
of navigation.”
NOTE-
1. Additional information and associated requirements
are available via a 90-series Advisory Circular 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 out-of-service
navaid may need to advise ATC of this intent and
capability.
b. Types of RNAV Systems that Qualify as a
Suitable RNAV System. When installed in accordance with appropriate airworthiness installation
requirements and operated in accordance with
applicable operational guidance (e.g., aircraft flight
manual and Advisory Circular material), the
following systems qualify as a suitable RNAV
system:
1. An RNAV system with TSO-C129/
-C145/-C146 (including all revisions (AR)) equipment, installed in accordance with AC 20-138
(including AR) or AC 20-130A, 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
7/31/08 AIM
AIM 2/14/1-2-6 Area Navigation (RNAV) and Required Navigation Performance (RNP)
2. An RNAV system with DME/DME/IRU
inputs that is compliant with the equipment
provisions of AC 90-100A, U.S. Terminal and
En Route Area Navigation (RNAV) Operations, for
RNAV routes.
NOTE-
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, NAVAID, or fix. 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. Allowable Operations. Operators may use a
suitable RNAV system in the following ways.
1. Determine aircraft position over or distance
from a VOR (see NOTE 4 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.
