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AIM

10/12/17

1−1−22

Navigation Aids

(5) GPS instrument approach/departure

operations outside the U.S. must be authorized  by

the appropriate sovereign authority.

4. Departures and Instrument Departure

Procedures (DPs)

The GPS receiver must be set to terminal (

±1 NM)

CDI sensitivity and the navigation routes contained in

the database in order to fly published IFR charted

departures and DPs. Terminal RAIM should be

automatically provided by the receiver. (Terminal

RAIM for departure may not be available unless the

waypoints are part of the active flight plan rather than

proceeding direct to the first destination.) Certain

segments of a DP may require some manual

intervention by the pilot, especially when radar

vectored to a course or required to intercept a specific

course to a waypoint. The database may not contain

all of the transitions or departures from all runways

and some GPS receivers do not contain DPs in the

database.  It is necessary that helicopter procedures be

flown at 70 knots or less since helicopter departure

procedures and missed approaches use a 20:1

obstacle clearance surface (OCS), which is double

the fixed−wing OCS, and turning areas are based on

this speed as well.

5. GPS Instrument Approach Procedures

(a) GPS overlay approaches are designated

non−precision instrument approach procedures that

pilots are authorized to fly using GPS avionics.

Localizer (LOC), localizer type directional aid

(LDA), and simplified directional facility (SDF)

procedures are not authorized. Overlay procedures

are identified by the “name of the procedure” and “or

GPS” (e.g., VOR/DME or GPS RWY 15) in the title.

Authorized procedures must be retrievable from a

current onboard navigation database. The naviga-

tion database may also enhance position orientation

by displaying a map containing information on

conventional NAVAID approaches. This approach

information should not be confused with a GPS

overlay approach (see the receiver operating

manual, AFM, or AFM Supplement for details on

how to identify these approaches in the navigation

database).

NOTE−

Overlay approaches do not adhere to the design criteria

described in Paragraph 5−4−5m, Area Navigation (RNAV)

Instrument Approach Charts, for stand−alone GPS

approaches. Overlay approach criteria is based on the

design criteria used for ground−based NAVAID ap-

proaches.

(b) Stand−alone approach procedures spe-

cifically designed for GPS systems have replaced

many of the original overlay approaches. All

approaches that contain “GPS” in the title (e.g.,

“VOR or GPS RWY 24,” “GPS RWY 24,” or

“RNAV (GPS) RWY 24”) can be flown using GPS.

GPS−equipped aircraft do not need underlying

ground−based NAVAIDs or associated aircraft

avionics to fly the approach. Monitoring the

underlying approach with ground−based NAVAIDs is

suggested when able. Existing overlay approaches

may be requested using the GPS title; for example,

the VOR or GPS RWY 24 may be requested as “GPS

RWY 24.” Some GPS procedures have a Terminal

Arrival Area (TAA) with an underlining RNAV

approach.

(c) 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 for the

approach integrity 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:

(1) Lateral navigation (LNAV) or circling

minimum descent altitude (MDA);

(2) LNAV/vertical navigation (LNAV/

VNAV) DA, if equipped with and using approved

barometric vertical navigation (baro-VNAV) equip-

ment;

(3) 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.

(d) If the above conditions cannot be met, any

required alternate airport must have an approved

instrument approach procedure other than GPS−

based that is anticipated to be operational and

available at the estimated time of arrival, and which

the aircraft is equipped to fly.