Garmin GNS 430 Pilot's Manual & Reference page 193

What does the O key do and when do I use it?
The O key is used to select manual (OBS mode) or automatic sequencing of waypoints. Activating
OBS mode (as indicated by an
'active to' waypoint as your navigation reference and prevents the GPS from sequencing to the next
waypoint. When OBS mode is cancelled, automat ic waypoint sequencing is selected, and the GNS 430
will automatically select the next waypoint in the fl ight plan once the aircraft has crossed the present
active-to waypoint.
NORMAL (no "OBS" annunciator)
Automatic sequencing of waypoints
Change in HSI does not affect CDI deflection
Always navigates 'TO' the active waypoint
Must be in this mode for final approach course
Whenever OBS mode is active, the GNS 430 allows you to select the desired course to/from a waypoint using the HSI (much like a VOR) and display
a to/from fl ag for the active-to waypoint. If an external course input is not available, you may select the OBS course on-screen, via a "Select OBS Course
pop-up window. With OBS mode cancelled, the CDI will always display a 'TO' indication for the next waypoint once you've crossed the active waypoint
(provided the active waypoint is not the last waypoint). Refer to page 72 for an example using the O key.
One application for the O key is holding patterns. The O key is used to suspend waypoint sequencing and select the desired course along the
annunciation directly above the O key) holds your current
OBS
Manual sequencing- 'holds' on selected waypoint
Manually select course to next waypoint from HSI
Will indicate 'TO' or 'FROM' waypoint
Cannot be set for final approach course or published holding patterns
waypoint side of the hold. For many approach operations, setting and resetting of waypoint sequencing is
automatic. Holding patterns that are part of an approach will automatically disable waypoint sequencing,
then re-enable waypoint sequencing after one time around the holding pattern. A "SUSP" annunciation
will appear directly above the O key (see illustration left) to indicate that automatic waypoint sequenc-
ing is temporarily suspended and course selection is not available. If more than one trip around the
holding pattern is desired, press the O key to again suspend waypoint sequencing. An example of this
operation is an approach which begins with a holding pattern at the initial approach fi x (IAF). See page 73
for more information on the "SUSP" annunciation and approaches with holding patterns.
APPENDIX D
TROUBLE-
SHOOTING
185