CBDR stands for Constant Bearing Decreasing Range — a target whose range is decreasing and bearing is not changing is on a collision course.

• A. CBDR stands for Constant Bearing Decreasing Range; a target whose range is decreasing and bearing is not changing is on a collision course.
• B. CBDR stands for Constant Bearing Decreasing Range; indicates no collision risk.
• C. CBDR stands for Constant Bearing Decreasing Range; indicates a safe passage.
• D. CBDR stands for Constant Bearing Decreasing Range; indicates a risk of grounding.

Answer: (A)

Constant bearing with decreasing range means the line of sight to the other vessel stays fixed while the distance between you shrinks. That configuration shows you are on a converging path toward the same line of travel, so if you both continue on current courses and speeds, a collision would occur. That’s why this scenario signals a risk of collision and requires early action to break the bearing—alter your course or speed to ensure the bearing changes and the distance stops closing.

The other statements don’t fit because CBDR does not indicate no risk, a safe passage, or grounding. It specifically flags that, with a fixed bearing and closing distance, collision is possible if no action is taken.