3. ARP OPERATION
3-8
3.9
CPA and TCPA Alarm
When the predicted CPA of any ARP/AIS target becomes smaller than a preset CPA alarm range
or its predicted TCPA less than a preset TCPA alarm limit, an audio alarm sounds and the collision
visual alarm is generated.. In addition, the target plot symbol of the offending target changes to a
triangle and flashes together with its vector. You may silence the audio alarm and acknowledge
the alarm with the
CANCEL/HL OFF
key. The flashing of the triangle plot symbol continues until
you intentionally terminate tracking of the target. The ARP continuously monitors the predicted
range at the Closest Point of Approach (CPA) and predicted time to CPA (TCPA) of each track to
own ship.
This feature helps alert you to targets which may be on a collision course with own ship. However,
it is important that GAIN, SEA, RAIN and other radar controls are properly adjusted and the ARP
is set up so that it can track targets effectively..
1. Press the
MENU
key to open the menu.
2. Choose Target and then press the
ENTER
key.
3. Choose CPA and then press the
ENTER
key.
4. Choose appropriate time and then press the
ENTER
key.
5. Choose TCPA and then press the
ENTER
key.
6. Choose appropriate TCPA and then press the
ENTER
key.
7. Press the
MENU
key to close the menu.
CAUTION
The CPA/TCPA alarm should never be
relied upon as the sole means for detect-
ing 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.
Off
0.5nm
1nm
2nm
3nm
5nm
6nm
30sec
1min
2min
3min
4min
5min
6min
12min
