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CAUTION
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
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 / TCPA Alarm
Status Symbol on display Alarm characters Alarm sound Conditions
Tracked target
Activated AIS
target
(Off) (Off)
• CPA > CPA LIMIT
• 0 > TCPA
• TCPA > TCPA LIMIT
The symbol is displayed when
one of the above conditions is
met.
Dangerous target
Red blinking
CPA / TCPA
Beep sound
(pee-poh)
Alarm
acknowledgeable
• 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 5.3.9.
CPA Limit and TCPA Limit: The Setting Values
12
AIS12
12
AIS12
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