What is the function of the "Trial Mode" used in most ARPA equipment?

The function of "Trial Mode" in most ARPA (Automatic Radar Plotting Aids) equipment is primarily to allow the user to assess the results of proposed maneuvers. This mode is essential for simulation and planning purposes, enabling operators to visualize how potential changes in course or speed would affect the navigation of both their own vessel and other nearby targets. By using Trial Mode, the operator can evaluate different maneuvering options in a user-friendly way, helping to ensure safe passage and effective collision avoidance.

Other options might refer to useful functions or data displays within ARPA systems, such as target predictions or recent positions, but they don't specifically represent the core capability of the Trial Mode. This mode focuses on examining hypothetical scenarios, making it a critical feature for navigational safety and decision-making.