What will cause the ARPA to emit a visual alarm, audible alarm, or both?

The ARPA (Automatic Radar Plotting Aid) system is designed to assist mariners in tracking the movement of vessels and can issue alarms under specific conditions to enhance situational awareness and collision avoidance.

The correct answer pertains to a tracked target entering your preset CPA (Closest Point of Approach) and TCPA (Time to Closest Point of Approach) limits. When a target's movement predicts that it will come within a defined safety margin that you have set in these parameters, the ARPA system recognizes this as a potential collision risk. As a result, it activates visual and/or audible alarms to alert the operator of the imminent danger. This is a crucial safety feature that enables timely evasive action to avoid collisions.

The other scenarios mentioned involve circumstances that may not necessarily trigger an alarm. For instance, an acquired target entering a guard zone might indicate a potential risk, but it is not solely reliant on CPA and TCPA data to signal an alarm through ARPA. Similarly, a tracked target lost for one radar scan may imply a temporary loss of data, which does not automatically meet the threshold for an alarm since the target might reappear in the next scan or the loss may not indicate an immediate risk. Lastly, while a target being initially detected within