AIM 

3/21/24 

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

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wing OCS, and turning areas are based on this speed as well. 

5.  GPS Instrument Approach Procedures 

(a) 

GPS overlay approaches are designated non

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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 navigation 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

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Overlay approaches do not adhere to the design criteria described in paragraph 5

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4

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5m, Area Navigation (RNAV) 

Instrument Approach Charts, for stand

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alone GPS approaches. Overlay approach criteria is based on the design criteria 

used for ground

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based NAVAID approaches. 

(b) 

Stand

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alone approach procedures specifically 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

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equipped aircraft do not need underlying 

ground

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based NAVAIDs or associated aircraft avionics to fly the approach. Monitoring the underlying approach 

with ground

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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()

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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

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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) equipment; 

(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

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based that is anticipated to be operational and available at the 

estimated time of arrival, and which the aircraft is equipped to fly. 

(e)  Procedures for Accomplishing GPS Approaches 

(1) 

An RNAV (GPS) procedure may be associated with a Terminal Arrival Area (TAA). The basic 

design of the RNAV procedure is the “T” design or a modification of the “T” (See Paragraph 5-4-5d, Terminal 

Arrival Area (TAA), for complete information). 

(2) 

Pilots cleared by ATC for an RNAV (GPS) approach should fly the full approach from an Initial 

Approach Waypoint (IAWP) or feeder fix. Randomly joining an approach at an intermediate fix does not assure 

terrain clearance. 

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Navigation Aids