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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. Note
that the GNC 250 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 0.3 nm
The GNC 250 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.
72
APPENDIX C
Maintenance
When the ‘auto’ CDI setting is selected, the
GNC 250 will automatically change the CDI
scale when you are within 30 nm of a departure
or arrival airport.
Entering a user magnetic variation.
SECTION
6
UNIT SETTINGS
CDI Settings
Magnetic Variation
250 real 7/14/98 9:33 AM Page 72