User's Manual

5－40
JMA-9172-SA Instruction Manual > 5.OPERATION OF TARGET TRACKING AND AIS > 5.5 ALARM DISPLAY
5.5.1 CPA / TCPA Alarm
In the system, targets are categorized into two types: tracked / activate AIS targets
and dangerous targets.
The grade of danger can easily be recognized on the display at a glance. So the
officer can easily decide which target he should pay attention to.
It is not possible to switch off the tracked target visual alarm, unless tracking is
ceased, or the alarm condition no longer applies.
The types of target and alarm are shown below.
CPA Limit and TCPA Limit: The Setting Values
Since these alarms may include some errors
depending on the target tracking conditions, the
navigation officer himself should make the final
decision for ship operations such as collision
avoidance.
Making the final navigation decision based only on the
alarm may cause accidents such as collisions.
CPA / TCPA Alarm
Status Symbol on
display
Alarm
characters
Alarm
sound
Conditions
Tracked target (Off) (Off)
・CPA>CPA LIMIT
・0>TCPA
・TCPA>TCPA LIMIT
The symbol is displayed
when one of the above
conditions is met.
Activated AIS
target
Dangerous
target
Red blinking
CPA/TCPA Beep
sound
(pee-poh)
Alarm
acknowle
dgeable
・CPA≦ CPA LIMIT
・0≦TCPA≦TCPA LIMIT
An alarm is issued when all
the conditions are met.
The AIS targets that issues
alarm refer to Section 5.3.9
Red blinking
12
AIS12
12
AIS12