Question 3426 Deck General

The correct answer is A) at the same time. According to the U.S. Coast Guard regulations, when a mobile offshore drilling unit on the waters of the U.S. Outer Continental Shelf has more than one obstruction light, the lights must be operated to flash at the same time. This is to ensure that the lights are clearly visible and provide a consistent visual signal to other vessels and aircraft in the area, alerting them to the presence of the obstruction. The other options are incorrect because they do not match the regulatory requirement for the lights to flash simultaneously. Flashing the lights in sequence at intervals of 5, 10, or 15 seconds would not provide the necessary visual cue for the obstruction.