L L Arm M O Des - Honeywell BENDIX/KING KAP 140 Maintenance Manual

2.10.2 ROLL ARM MODES
2.10.2.1 Navigation Arm Mode (NAV ARM)
The NAV arm mode determines when to automatically activate the NAV coupled mode. The NAV
mode is activated whenever the NAV button is pressed and NAV (arm or coupled) mode is not
already active. The NAV ARM mode can be deactivated by selecting APR ARM or REV ARM mode
or by pressing the NAV pushbutton again. When the NAV mode is selected, if the NAV deflection
exceeds the forced capture requirements of the NAV mode, then the NAV ARM mode is activated
and a compatible lateral mode (i.e., HDG) can be used to intercept the desired course or track.
If the aircraft deviation from the selected course centerline is sufficiently small, or if the rate of
closure with the new course is sufficiently high, NAV coupled mode is initiated immediately.
When in the NAV arm mode, "NAV ARM" will be annunciated in the roll arm field. If the NAV Valid
remains invalid for 30 seconds or the DG Valid remains invalid for five (5) seconds while in the ARM
mode, the NAV ARM mode automatically deactivates, leaving the current coupled mode active.
2.10.2.2 Approach Arm Mode (APR ARM)
The APR arm mode determines when to automatically activate the APR coupled mode. The APR
mode is activated when the APR button is pressed and the APR mode is not already active. The
APR mode can be deactivated by disengaging the AP or by pressing the APR, NAV, or REV
pushbutton. When the APR mode is selected, if the NAV deviation exceeds the forced capture
requirements of the APR mode, then the APR ARM mode is activated and a compatible lateral
mode (i.e., HDG) can be used to intercept the desired course or track. If the NAV deviation is
sufficiently small, or if the rate of closure is sufficiently high, APR Capture is activated immediately.
When in the APR ARM mode, "APR ARM" is displayed in the roll arm field. If the NAV sensor
becomes invalid for a period of 30 seconds or the DG Valid becomes invalid for 5.0 seconds while
in the ARM mode, the APR ARM mode automatically deactivates, leaving the current coupled
mode active.
2.10.2.3 Reverse Localizer Arm Mode (REV ARM)
Reverse Localizer arm mode is similar to APR arm mode, but determines the transition point for
REV coupled mode. It is annunciated by "REV ARM" in the roll arm field.
2.10.2.4 ARM modes with DG
The lateral mode logic and annunciation described in the rest of this document applies to an HSI
installation. DG installations provide the following differences. When the installation uses a DG
instead of an HSI, the heading bug will be used in place of the course pointer for lateral arm modes.
Therefore, HDG mode is not compatible with arm modes, since it also uses the heading bug. To
compensate for this, DG installations have an additional coupled mode, known as autointercept
mode.
Revision 2, Dec/2002
CS:15574F02.IDU
BENDIX/KING
KAP 140
Page 2--16