What signal should you transmit if you need to call for urgent help?

Transmitting "MAYDAY, MAYDAY, MAYDAY" is the recognized international distress signal intended for situations where life is in immediate danger. This phrase specifically indicates that the vessel is in grave and imminent danger and requires urgent assistance. The repetition of "MAYDAY" three times serves to emphasize the severity of the situation, ensuring that the message is clearly understood and prompts immediate action from personnel monitoring marine communications.

In contrast, the other options, while indicating a need for help, do not hold the same level of urgency or universal recognition. For instance, "HELP, HELP, HELP" may communicate a need for assistance but does not convey the critical nature of the situation as effectively. Similarly, "ASSISTANCE, ASSISTANCE, ASSISTANCE" and "EMERGENCY, EMERGENCY, EMERGENCY" do not have the same established protocol in maritime communication. Therefore, using "MAYDAY" is paramount for ensuring that the response you receive is swift and appropriate to the level of danger faced.