'Oscar' is a signal indicating what situation?

The signal 'Oscar' specifically indicates a situation involving a man overboard. In naval operations, it is crucial to have clear and concise communication regarding emergencies, especially when someone has fallen overboard. When the signal 'Oscar' is used, it alerts the crew to the presence of a person in the water and requires immediate action to locate and rescue that individual. This signal is part of a standardized set of flags used in maritime contexts to communicate different conditions or requirements without verbal communication, ensuring that all crew members understand the urgency of the situation.

The other options represent different signals or commands which do not pertain to a man overboard scenario. 'All personnel return to ship' and 'Boat recall' are commands that involve regrouping but do not signify an emergency situation. 'Do not pass ahead of me' is a navigational command that indicates caution in maneuvering but also does not relate to the critical situation of someone in the water. Understanding these distinctions is vital for effective communication and response in naval operations.