Honeywell SPZ-8000 - Dual Couple (CPL) Approach Mode

SPZ--8000 Digital Integrated Flight Control System
A28--1146--055
REV 2
Modes of Operation
8-36
The approach mode is cancelled by:
D Pushing the APP, NAV, or HDG buttons on the flight guidance
controller
D Selecting go--around mode
D Selecting standby mode
D Coupling to the cross--side EHSI
D T uning a different NAV frequency or source.
DUAL COUPLE (CPL) APPROACH MODE
During the tracking phase of an ILS approach, the system uses localizer
and glideslope flightpath information from both the pilot’s and copilot’s
EHSI. This dual couple mode gives fail--operational performance for the
safety critical segment of the approach. The dual--coupled approach is
flown as described in Table 8--4.
Step
Procedure
1 Tune both NAV receivers to the ILS frequency for the
approach runway.
2 Set the same selected course on both EHSIs.
NOTES: 1. When both the localizer and glideslope signals are on track,
radio altitude is below 1200 feet, and both navigation
receivers are valid, the system transitions to the dual HSI
mode of operation. When this mode is active, both CPL
arrows on the flight guidance controller light.
2. In this mode, both flight guidance computers use information
from both navigation receivers. This means the approach
can continue even if the one navigation receiver fails. If one
receiver fails, the arrow associated with that receiver on the
flight guidance controller goes out and the aproach mode
remains active.
Dual Couple Approach Procedure
Table 8- -4
In a dual couple approach, both flight guidance computers use
averaged ILS data, perform the same computations, and send identical
flight director commands to their respective EADIs.
Although the flight guidance computer uses averaged ILS data for
guidance, each symbol generator performs excessive deviation
monitoring on non--averaged data. Therefore, the excessive deviation
monitor on one side is related to the on--side displayed ILS data.