🔍 Key Concepts

• GMDSS distress alerting uses several different technologies (VHF/MF/HF DSC, satellite EPIRBs, and Inmarsat). • The question asks about frequencies and modes allocated for distress alerting, not general communications. • Each option lists a different system or band used within GMDSS.

💭 Think About

• Ask yourself: Does GMDSS rely on only one of these systems, or multiple, to ensure redundancy for distress alerting? • Consider whether EPIRBs on 406 MHz and Inmarsat distress services are also part of the official GMDSS distress alerting system. • Think about which answer choice best reflects the full set of primary distress alerting methods required under GMDSS.

✅ Before You Answer

• Verify which DSC (Digital Selective Calling) channels/frequencies are officially designated for distress alerting on VHF and MF/HF. • Confirm that 406 MHz EPIRBs are specifically allocated for distress alerting to the COSPAS-SARSAT system. • Check whether the 1626.5–1645.5 MHz band is associated with Inmarsat ship earth stations for distress and safety communications under GMDSS.