Tt Collision Alarm; Setting Cpa And Tcpa Ranges - Furuno FCR-2107 Series Operator's Manual

4. Tracked Target (TT) Operation
4.13

TT Collision Alarm

The TT continuously monitors the predicted range at the Closest
Point of Approach (CPA) and predicted time to CPA (TCPA) of
each TT. When the predicted CPA of any TT becomes smaller
than a preset CPA range and its predicted TCPA less than a
preset TCPA limit, the audio alarm sounds and TT COLLISION
appears (in red) in the Alert Box. In addition, the symbol of the
offending TT is red and flashes together with its vector.
This feature, when used correctly, helps 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.
CPA and TCPA settings must be set up properly taking into consideration the size, tonnage, speed, turning
performance and other characteristics of own ship.
4.13.1

Setting CPA and TCPA ranges

To set the CPA and TCPA ranges, do the following:
1. Use the trackball to select "CPA" of "CPA Off" at the lower right corner. Push the left button to show the CPA
and TCPA boxes.
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CPA and TCPA settings
2. Spin the scrollwheel to select the CPA setting desired (0.5-20 nm) then push the scrollwheel.
3. Use the trackball to select the TCPA setting.
2. Spin the scrollwheel to select TCPA value desired (1-60 m) then push the scrollwheel.
Acknowledging the TT collision alarm
The TT collision alarm sounds when the CPA or TCPA of an target is within the set CPA/TCPA. To acknowledge
and silence the alarm, push the ALARM ACK key on the keyboard, or select the ALARM ACK box with the
trackball then push the left button.
The warning label TT COLLISION and the flashing of the triangle plotting symbol and vector remain in the Alert
Box until the dangerous situation is gone or you intentionally terminate tracking of the target.
4-18
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CAUTION
TT Collision Alarm
The TT collision alarm feature should
never be relied upon as the sole means
for detecting risk of collision. The
navigator is not relieved of the respon-
sibility to keep visual lookouit for
avoiding collisions, whether or not the
radar or other navigation aid is in use.