Emergency calls on the radio should start with which phrase?

The phrase "Emergency, emergency, emergency" is the correct choice for initiating emergency calls on the radio because it is a standardized way to communicate a sense of urgency and to ensure that the call is taken seriously by all receiving parties. This repetition helps to cut through any background noise and grabs the attention of anyone listening in on the frequency, making it clear that the situation is critical and immediate attention is required.

Using "Emergency, emergency, emergency" aligns with common communication protocols in emergency situations, ensuring that the message is delivered effectively and promptly. This phrase is recognized by responders and operators as a signal that urgent, potentially life-threatening circumstances need assistance, thus promoting a rapid response.

In contrast, the other phrases, while they may convey urgency, do not carry the same standardized recognition in emergency radio communications. "Attention, emergency" could imply a less formal alert, while "Mayday" has specific maritime connotations and might not be universally understood in all contexts. "Help, help, help" is also not as widely accepted or clear in emergency protocol, thereby lacking the clarity established by the standardized emergency call.