Which call should be used to indicate the highest urgency in distress?

The call that indicates the highest urgency in distress is "MAYDAY." This term is internationally recognized in maritime and aviation distress communication, signifying that a vessel or aircraft is in grave and imminent danger and requires immediate assistance. When a MAYDAY call is transmitted, it alerts all nearby vessels and authorities of a life-threatening situation, prompting them to prioritize the emergency response.

MAYDAY is typically repeated three times to ensure clarity and urgency. This standardized protocol is essential to effectively communicate the seriousness of the situation, ensuring that help can respond as quickly as possible. The urgency associated with a MAYDAY call often involves scenarios such as sinking, a fire on board, or serious medical emergencies that threaten the safety of individuals on board.

In contrast, SECURITE is used for broadcasting navigational or safety information and does not indicate distress. PAN PAN signals an urgent situation but not one that requires immediate assistance, as it concerns safety rather than life-threatening emergencies. SOS is an older distress signal that is also widely recognized, but MAYDAY is the more modern and preferable choice in real-time situations due to the clarity and specific guidelines surrounding its use.