Why must all VHF Distress, Urgency and Safety communications be performed in Simplex mode?

The correct answer emphasizes the necessity for VHF Distress, Urgency, and Safety communications to be conducted in Simplex mode to ensure clear and effective communication during emergencies. Simplex mode allows for one party to transmit while the others listen, which is crucial for distress communications. This mode ensures that vessels not directly involved in the ongoing communication can hear both sides of the exchange, which is vital for coordination and assistance in search and rescue operations.

When multiple vessels or stations might be involved, it’s important that all parties can obtain complete information, ensuring that all listening vessels receive the same distress call, follow-up instructions, or safety messages. This collective awareness helps in mobilizing assistance and coordinating responses more effectively. In contrast, other modes such as duplex (which allows simultaneous transmission and reception) could lead to confusion and missed critical information among vessels monitoring the distress channels. Thus, using Simplex mode enhances the safety and efficacy of marine communications during emergencies.