Red over red navigation lights indicate which condition?

• A. Not under command
• B. Pilot ahead
• C. Constrained by draft
• D. Towing at night

Answer: (A)

Two red lights stacked vertically signal a vessel not under command. This means the vessel cannot maneuver to comply with the collision regulations, often due to engine or steering failure. Because it can’t take proper action to avoid others, other vessels must keep well clear and take early, substantial action to avoid it. When you observe this signal, reduce speed and give it a wide berth if safe.

Other conditions have different signaling patterns, such as those used for towing, pilots on board, or other maneuvering limitations, so red-over-red is specifically the indication for not under command.