🔍 Key Concepts

• GMDSS Sea Area A3 coverage and what systems it relies on (Inmarsat, HF DSC, etc.) • The difference between distress calling channels/frequencies (DSC) and voice distress frequencies • Which frequencies/channels are no longer primary for distress alerting under GMDSS (e.g., traditional 2182 kHz)

💭 Think About

• First decide: in Sea Area A3, is the main requirement based on VHF + MF/HF DSC, or on old voice distress channels? • Look at each option and ask: which one focuses on DSC distress alerting frequencies versus legacy voice calling frequencies? • Identify which frequencies listed are DSC channels/frequencies and which are radiotelephone (voice); then think which the regulations require to be continuously watched in A3.

✅ Before You Answer

• Verify which option uses 2187.5 kHz (MF DSC) instead of 2182.0 kHz (MF voice) for distress watchkeeping. • Check that the HF frequencies required are HF DSC distress/urgency frequencies, not just HF voice channels. • Confirm whether a continuous watch on VHF Channel 16 (voice) is still a mandatory GMDSS Sea Area A3 requirement, or if VHF Channel 70 (DSC) is the primary GMDSS watch channel.