Which statement best identifies signaling for a vessel not under command?

• A. One red light
• B. Two all-round red lights in a vertical line
• C. Two red lights in a diagonal line
• D. Red light paired with a white light

Answer: (B)

Not under command is shown by two all-round red lights in a vertical line. This signal tells other vessels that the vessel cannot maneuver as required by the Rules and may not respond to steering or stopping actions. The vertical pair of red lights is visible from all directions and signals the need for other ships to take early, substantial action to avoid a collision. Day signals mirror this with two black balls in a vertical line. This pattern is distinct from other statuses, such as restricted in its ability to manoeuvre (which uses three red all-round lights in a vertical line).