Which emergency signal is used to indicate a great danger to life or vessel?

The signal that indicates a great danger to life or vessel is Mayday. This term is internationally recognized and is used specifically in emergency situations where there is an immediate threat. When someone sends a Mayday signal, it conveys that they are in dire need of help, and responders prioritize such calls due to the potential loss of life or severe damage to property.

Mayday signals are critical for maritime and aviation communications, ensuring that authorities and rescue services take immediate action. This distinction in terminology is essential in emergencies, as it allows for clear communication and rapid response from rescue services, emphasizing the urgency associated with a situation requiring a Mayday call.