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The first available page under the settings submenu is the CDI settings page,
which allows you to define the scale of the GNC 300’s course deviation indicator.
To change the CDI scale:
1. Press and hold
M
, and rotate
O
to select the CDI settings page.
2. Press
C
twice and rotate
K
to select ‘Auto’, ‘
+
-
5.0 nm’, ‘
+
-
1.0 nm’ or ‘
+
-
0.3 nm’.
3. Rotate
O
to highlight ‘ok?’ and press
E
to approve.
Note: the selected CDI scale will not take effect until approved.
The scale values represent full scale deflection of the CDI to either side. The
default setting is
+
-
5.0 nm. The ‘Auto’ setting will start the CDI scale at 5 nm, and
gradually ramp down the scale to the 1 nm range once you are within 30 nm of a
departure or arrival airport. You must have an active direct-to or route with an airport
as your final destination waypoint, or be within 30 nm of a departure airport. If you
have an active approach, the scale will gradually ramp down to the 0.3 nm range
once you are within 2 nm of the final approach fix.
Note that the GNC 300 uses Receiver Autonomous Integrity Monitoring
(RAIM) to cross-check its position. The RAIM protection limits listed below follow
the selected CDI scale, changing automatically with the ‘Auto’ setting:
CDI Scale RAIM Protection
+/-5.0 nm or Auto (en route) 2.0 nm
+/- 1.0 nm or Auto (terminal) 1.0 nm
+/- 0.3 nm or Auto (approach) 0.3 nm
The GNC 300 has three
magnetic variation options:
true, auto, or user-defined.
To set the magnetic variation:
1. Press and hold
M
and use
O
to display the ‘Mag Var/Arvl Alarm’ page.
2. Press
C
twice and use
K
to select auto, true or user.
3. If user is selected, use
O
to highlight the magnetic variation value, and use
K
and
O
to enter the value and E or W. Press
C
to finish.
96
APPENDIX C
Maintenance
Entering a user magnetic variation.
SECTION
7
UNIT SETTINGS
CDI Settings
Magnetic Variation
When the ‘Auto’ CDI setting is selected, the
GNC 300 will automatically change the CDI
scale when you are within 30 nm of a departure
or arrival airport. During approach operations,
the ‘Auto’ setting will be automatically selected to
provide a smooth CDI transition from the 5.0 nm
to the 0.3 nm scale.
300 7/14/98 8:51 AM Page 96