Honeywell BENDIX/KING KAP 140 Maintenance Manual page 37

2.10.1.4 Navigation Coupled Mode (NAV)
The NAV coupled mode provides roll commands to capture and track the selected NAV course on
the HSI. The preferred intercept is between 30 and 60 degrees, however, the AFCS performs all
angle intercepts if course datum is provided. When passing over the VOR station, the FCC
commands values that provide stable heading and ignore the erratic VOR deviations in the "cone
of confusion". While over the station, course changes are made by selecting a new outbound
course on the HSI.
The NAV coupled mode is activated automatically following the selection of the NAV mode, as
described in the section below on NAV Arm mode. When NAV capture occurs, the NAV coupled
mode cancels any other lateral coupled mode. The NAV coupled mode can be deactivated by
selecting another lateral mode or by pressing the NAV pushbutton again.
When in the NAV coupled mode, "NAV" will be annunciated in the roll coupled field. If the NAV Valid
remains invalid for 5 seconds (15 seconds for VOR) or DG Valid remains invalid for 5 seconds, the
NAV annunciation flashes and the system reverts to the roll default mode. The flashing of the NAV
annunciation continues until canceled by pressing the NAV pushbutton or until another lateral
mode has been selected. Upon deactivation of the flashing, the current selected roll coupled mode
is annunciated. For --27XX, --55XX and --79XX versions, roll steering is also active in this mode.
2.10.1.5 Approach Coupled Mode (APR)
The APR coupled mode provides commands to capture and track the selected NAV sensor within
the required approach accuracies. The APR coupled mode is activated automatically following the
selection of the APR mode, as described in the section on APR Arm mode. When APR capture
occurs, the APR coupled mode cancels all other lateral modes. The APR coupled mode can be
deactivated by pressing the APR button again or by selecting another roll mode.
When in the APR coupled mode, "APR" is displayed in the roll coupled field. In the event the NAV
deviation information becomes invalid for 5 seconds (15 seconds with VOR) or DG Valid remains
invalid for 5 seconds, the APR annunciation flashes and the FCC reverts to the roll default mode.
The flashing of the APR indicator on the MSP continues until canceled deactivated by pressing
the APR button again or by selecting another roll mode. Upon deactivation of the flashing, the
current selected mode(s) is annunciated. For --27XX, --55XX and --79XX versions, roll steering is
also active in this mode.
2.10.1.6 Reverse Localizer Coupled Mode (REV)
Reverse Localizer mode is similar to the APR mode (described above) except the GS mode is
disabled and the deviation gains are reduced to provide backcourse tracking.
Revision 2, Dec/2002
CS:15574F02.IDU
BENDIX/KING
KAP 140
Page 2--15