Annunciators/Switches - Garmin GNC 420A Installation Manual

4.5

ANNUNCIATORS/SWITCHES

4.5.1 Annunciators/Switches Function
Initial certification of the 400 Series units was accomplished without use of any remote switches or
annunciators, since the same switching and annunciation is available on the front panel of the 400
Series unit. However, if the 400 Series unit is not installed in the pilot's normal field of view, some or all
of the remote switches and annunciators may be required by your certification agency. Appendix B
includes an FAA letter granting permission to install GNS 430 without external switches and annunciators.
4.5.1.1 MESSAGE ANNUNCIATE
When a new status message is available, the Message Annunciator flashes. When status messages remain
effective, the Message Annunciator illuminates.
4.5.1.2 WAYPOINT ANNUNCIATE
The waypoint annunciator output is driven in the following manner:
1. When the aircraft is within 10 seconds of reaching the turning point for a course change, the
waypoint annunciator flashes.
2. When the aircraft is in a turn, the waypoint annunciator illuminates and remains illuminated until
the turn is completed.
3. When a user arrival alarm is set and the aircraft is within the circle defined by the arrival alarm
radius at the arrival waypoint, the waypoint annunciator flashes for 10 seconds.
4. When a user arrival alarm is not set and the aircraft is within 10 seconds of reaching the arrival
waypoint, the waypoint annunciator flashes.
4.5.1.3 CDI SOURCE SELECT (GNS 430 Only)
This discrete input may be used to toggle between display of GPS and VOR/LOC/Glideslope information
on the MAIN external CDI/HSI. A momentary low on this pin performs the same function as pressing the
'CDI' key on the GNS 430 bezel.
4.5.1.4 VLOC ANNUNCIATE (GNS 430 Only)
This annunciator output is driven when the unit is configured with a single CDI/HSI and the VOR/ILS data
is being displayed on the CDI/HSI. This output parallels the VLOC annunciator on the display.
4.5.1.5 GPS ANNUNCIATE (GNS 430 Only)
This annunciator output is driven when the unit is configured with a single CDI/HSI and the GPS data is
being displayed on the CDI/HSI. This output parallels the GPS annunciation on the display.
4.5.1.6 OBS MODE SELECT
This discrete input may be used to toggle between GPS OBS and GPS AUTO modes of operation. A
momentary low on this pin performs the same function as pressing the 'OBS' key on the 400 Series unit.
4.5.1.7 AUTO ANNUNCIATE
This annunciator output is driven to indicate GPS AUTO mode of operation. This output is active when
neither the OBS nor SUSP annunciations are on the display.
4.5.1.8 OBS ANNUNCIATE
This annunciator output is driven to indicate GPS OBS mode of operation. This output is active when the
OBS or SUSP annunciation is on the display.
4.5.1.9 TERMINAL ANNUNCIATE
When performing approach navigation, the terminal annunciator is illuminated when operating within 30
nautical miles of the departure or arrival airport and the CDI scale is the equivalent or 1.0 nm or less.
4.5.1.10 APPROACH ANNUNCIATE
When performing approach navigation, the approach annunciator illuminates when approach is active.
4.5.1.11 INTEGRITY ANNUNCIATE
The integrity annunciator illuminates when the GPS receiver detects a position error, or is unable to
calculate the integrity of the position.
400 SERIES INSTALLATION MANUAL
P/N 190-00140-02
NOTE
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