Furuno FEA-2107-BB - Expected Steering Performance under Critical Failure; Lost Heading from Autopilot (ECDIS May also Have Lost Heading)

29. Steering With YOKOGAWA Autopilot PT-500A
29-14
29.8 Expected Steering Performance Under Critical
Failure
Below is a summary of system behaviour in various failures when the "NAVI" steering mode is used.
29.8.1 Lost heading from autopilot (ECDIS may also have lost
heading)
Associated alarms Expected system performance What end operator
should do
Immediately Autopilot Alarm
"EMERGENCY-05 Gyro
Compass" is generated on Auto
pilot control panel
Sensor alarm "4055: Gyro error
(Autopilot FAP-2000)" is
generated at ECDIS.
If ship is in linear part, Rudder order
is frozen for last value in order to
approximately continue ahead.
If ship is turning, rudder order is
frozen for last value in order to
approximately continue rate of turn.
Change immediately to
manual control of rudder.
Acknowledge alarms.
Study situation.
Within few
seconds
Alarm "2497 Route Stop-Sensor
fail.
Alarm "2471 AP mode conflict -
Use AUTO" on ECDIS"
Change immediately to
manual control of rudder.
Acknowledge alarms.
Study situation.
Repeat
every 2
minutes
Alarm "2498 Use manual rudder
control" is generated at ECDIS.
Reminder Change immediately to
manual control of rudder.