AIM

4/3/14

1−1−30

Navigation Aids

course even though it is on an acceptable intercept

heading. Referencing the digital track displacement

information (cross track error), if it is available in the

approach mode, may help the pilot remain position

oriented in this situation. Being established on the

final approach course prior to the beginning of the

sensitivity change at 2 NM will help prevent

problems in interpreting the CDI display during ramp

down. Therefore, requesting or accepting vectors

which will cause the aircraft to intercept the final

approach course within 2 NM of the FAWP is not

recommended.

6.

When receiving vectors to final, most

receiver operating manuals suggest placing the

receiver in the nonsequencing mode on the FAWP

and manually setting the course. This provides an

extended final approach course in cases where the

aircraft is vectored onto the final approach course

outside of any existing segment which is aligned with

the runway. Assigned altitudes must be maintained

until established on a published segment of the

approach. Required altitudes at waypoints outside the

FAWP or stepdown fixes must be considered.

Calculating the distance to the FAWP may be

required in order to descend at the proper location.

7.

Overriding an automatically selected sensit-

ivity during an approach will cancel the approach

mode annunciation. If the approach mode is not

armed by 2 NM prior to the FAWP, the approach

mode will not become active at 2 NM prior to the

FAWP, and the equipment will flag. In these

conditions, the RAIM and CDI sensitivity will not

ramp down, and the pilot should not descend to MDA,

but fly to the MAWP and execute a missed approach.

The approach active annunciator and/or the receiver

should be checked to ensure the approach mode is

active prior to the FAWP.

8.

Do not attempt to fly an approach unless the

procedure in the on−board database is current and

identified as “GPS” on the approach chart. The

navigation database may contain information about

nonoverlay approach procedures that is intended to

be used to enhance position orientation, generally by

providing a map, while flying these approaches using

conventional NAVAIDs. 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

procedures in the navigation database). Flying point

to point on the approach does not assure compliance

with the published approach procedure. The proper

RAIM sensitivity will not be available and the CDI

sensitivity will not automatically change to

±0.3 NM. Manually setting CDI sensitivity does not

automatically change the RAIM sensitivity on some

receivers. Some existing nonprecision approach

procedures cannot be coded for use with GPS and will

not be available as overlays.

9.

Pilots should pay particular attention to the

exact operation of their GPS receivers for performing

holding patterns and in the case of overlay

approaches, operations such as procedure turns.

These procedures may require manual intervention

by the pilot to stop the sequencing of waypoints by the

receiver and to resume automatic GPS navigation

sequencing once the maneuver is complete. The same

waypoint may appear in the route of flight more than

once consecutively (e.g., IAWP, FAWP, MAHWP on

a procedure turn). Care must be exercised to ensure

that the receiver is sequenced to the appropriate

waypoint for the segment of the procedure being

flown, especially if one or more fly−overs are skipped

(e.g., FAWP rather than IAWP if the procedure turn

is not flown). The pilot may have to sequence past one

or more fly−overs of the same waypoint in order to

start GPS automatic sequencing at the proper place in

the sequence of waypoints.

10.

Incorrect inputs into the GPS receiver are

especially critical during approaches. In some cases,

an incorrect entry can cause the receiver to leave the

approach mode.

11. A fix on an overlay approach identified by a

DME fix will not be in the waypoint sequence on the

GPS receiver unless there is a published name

assigned to it. When a name is assigned, the along

track to the waypoint may be zero rather than the

DME stated on the approach chart. The pilot should

be alert for this on any overlay procedure where the

original approach used DME.

12.

If a visual descent point (VDP) is published,

it will not be included in the sequence of waypoints.

Pilots are expected to use normal piloting techniques

for beginning the visual descent, such as ATD.

13.

Unnamed stepdown fixes in the final

approach segment will not be coded in the waypoint

sequence of the aircraft’s navigation database and

must be identified using ATD. Stepdown fixes in the

final approach segment of RNAV (GPS) approaches