What is a primary function of ARPA in navigation?

• A. It assists automatic tracking and collision avoidance
• B. It measures wind speed
• C. It predicts weather
• D. It adjusts engine power

Answer: (A)

ARPA’s main job is to automatically track radar targets and support collision avoidance. It processes radar returns to identify multiple moving targets, calculates their courses and speeds, and predicts where they will be in the future. By computing metrics like the Closest Point of Approach and Time to Closest Point of Approach, ARPA can alert you to potential collision risks and assist in planning safe maneuvering. This automation reduces workload for the navigator and enhances safety in busy waters.

Wind speed measurement, weather prediction, and adjusting engine power are handled by other systems and functions, not ARPA. Wind and weather data come from meteorological instruments and weather radar, while engine power control is managed by propulsion and autopilot systems.