The height above airport alert feature does
not serve the same function as a radar
altimeter. It does not provide any warning
about the aircrafts actual height above the
airports surrounding terrain.
The height above airport alert feature will
only be accurate if the barometric altimeter
setting is correct. If the height above
airport function is enabled, ensure the
barometric altimeter setting is correct on
the ALT page.
(1) When the height above airport is enabled,
the KLN 90B creates a 5-nm radius cylinder of
airspace centered on an airport. This airport is any
airport that is a direct to waypoint or is the to waypoint
in the active flight plan. The height of the cylinder
above the airport is the height selected on the SET 5
page. The KLN 90B adds the selected altitude to the
elevation stored in the database for the airport. The
KLN 90B provides an altitude alert light when the
aircraft first penetrates the cylinder.
(2) To enable or disable the height above the
airport alert, press the left CRSR button. Use the left
enable/disable field. Turn the left inner knob to select
ON or OFF. To select the height, use the left outer
knob to position the cursor over the altitude field. Turn
the left inner knob to select an offset between 800 and
2000 feet. Press the left CRSR button to turn off the
g. The Setup 6 Page. Turn anticipation may be
enabled or disabled on the SET 6 page. Refer to
Figure 3D-86. Turn on the left cursor function and use
the left inner knob to select between ENABLE or
DISABLE. If turn anticipation is disabled, navigation is
provided all the way to the waypoint and waypoint
alerting occurs approximately 36 seconds prior to
actually reaching the waypoint.
Figure 3D-86. SET 6 Page
h. The Setup 7 Page. The SET 7 page is used
to select whether the altimeter setting used in the KLN
90B is made in inches of Mercury or millibars. Refer to
Figure 3D-87. To change the altimeter setting
between inches of Mercury and millibars, select the
SET 7 page, press the left CRSR button, and rotate
the left inner knob to make the selection. When
finished, press the left CRSR button to turn off the
Figure 3D-87. SET 7 Page
i. The Setup 8 Page. The Special Use
Airspace (SUA) alert feature may be enabled or
disabled on the SET 8 page. Refer to Figure 3D-88.
After displaying the SET 8 page on the left side, press
the left CRSR button to turn on the left cursor function.
The left inner knob is used to display AIRSPACE
ALERT ENABLE or AIRSPACE ALERT DISABLE. If
the SUA feature has been enabled, the KLN 90B
allows the selection of a vertical buffer in order to
provide a vertical warning of SUA. To select a vertical
buffer, ensure the SUA feature has been enabled.
Press the left CRSR button to turn on the left cursor
and then use the left outer knob to move the cursor
over the first position of the vertical buffer. Use the left
inner knob to select each number and the left outer
knob to position the cursor. The buffer may be
selected in 100-foot increments. After the desired
selection has been made, press the left CRSR button
to turn off the cursor function.