The alarm signal for a Man Overboard is three long blasts on the general alarm and ship's whistle. If you hear this alarm, muster on the main deck and attempt to maintain visual contact of the victim while pointing in the victims direction when in sight.

To alert the entire crew of a "man overboard" (MOB) situation, the primary audible signal is three prolonged blasts on the ship's whistle and the sounding of the general alarm. This is often supplemented by a vocal announcement over the ship's public address system, such as "Man Overboard, Port Side!" to indicate the direction of the fall. Visually, the ship may hoist the International Flag "O" (Oscar), which is a diagonally split yellow and red flag signifying "Man Overboard." On the bridge, officers immediately press the MOB button on the GPS to mark the exact coordinates of the incident. In 2026, modern safety protocols under SOLAS also involve deploying a "lifebuoy with light and smoke," which provides a visual marker for both the rescuers and the person in the water. The crew then initiates specific maneuvers, such as the Williamson Turn, to bring the vessel back to the marked position as quickly as possible. Rapid communication is vital, as survival time decreases quickly in rough or cold waters.