Onwa Marine Electronics KR-12X8 - Manual (Page 76)

CPA/TCPA Alarm
Visual and audible alarm are generated when the predicted CPA and TCPA of any
target become less than their preset limits. The audible alarm continues for 10 se-
conds.
The Auto plotter ARPA continuously monitors the predicted range at the Closest
Point of Approach (CPA) and predicted time to CPA(TCPA) of each tracked target
to own ship.
When the predicted CPA of any target becomes smaller than a preset CPA alarm
range and its predicted TCPA less than a preset TCPA alarm limit, the ARPA
releases an audible alarm. In addition, the target plot symbol changes to a triangle
and flashes together with its vector.
Provided that this feature is used correctly, it will help prevent the risk of collision
by alerting you to threatening targets, It is important that GAIN, A/C SEA, A/C
RAIN and other radar controls are properly adjusted and the Auto Plotter is set up
so that it can track targets effectively.
CPA/TCPA alarm ranges must be set up properly taking into consideration the size,
tonnage, speed, turning performance and other characteristics of own ship.
WARNING
The CPA/TCPA alarm feature should never be relied
upon as a sole means for detecting the risk of collision.
The navigator is not relieved of the responsibility to keep
visual lookout for avoiding collisions, whether or not the
radar or other plotting aid is in use.
Follow the steps shown below to set the CPA/TCPA alarm ranges:
1. Open the "ARP MENU".
2. On the "CPA Set"line, select a CPA limit desired.(Off,0.5,1,2,3,5,6nm)
3. Press the [ACQ/ENTER] key.
4. On the "TCPA Set"line, select a TCPA limit desired.(30s,1,2,3,4,5,6,12M)
5. Press the [ACQ/ENTER] key.
6. Press the [MENU] key to close the menu.
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