Which flag signifies Man Overboard?

The Oscar Flag, which is a square flag that is divided diagonally with a yellow top half and a black bottom half, is recognized internationally as the signal for "Man Overboard." When this flag is displayed, it serves to alert other vessels and nearby personnel that someone has fallen overboard and that immediate assistance is required. The use of the Oscar Flag is consistent across maritime communication standards, such as the International Code of Signals, which aids in ensuring a rapid response in such emergencies.

In contrast, the Bravo Flag is used to indicate that the vessel is loading or unloading explosives, the Alpha Flag signals that a vessel is conducting underwater operations, and the Papa Flag signifies a message related to "Proceeded to Port." Each of these flags has distinct meanings and purposes, but none are associated with the emergency situation of a person overboard, underscoring why the Oscar Flag is the correct choice.