background image

6/17/21 

AIM 

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 non

sequencing 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 

sensitivity 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 onboard database is current and 
identified as “GPS” on the approach chart. The 
navigation database may contain information about 
non

overlay approach procedures that enhances 

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 Supple-
ment 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 non

precision 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 (for example, 
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 (for example, 

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 identi-

fied 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 distance (ATD) 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 may or may 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 are being named, in 
addition to being identified by ATD. However, GPS 
avionics may or may not accommodate waypoints 
between the FAF and MAP. Pilots must know the 
capabilities of their GPS equipment and continue to 
identify stepdown fixes using ATD when necessary. 

Navigation Aids 

1

1

27