🔍 Key Concepts

• GMDSS sea areas (A1–A4) and which equipment/watchkeeping applies to each • The difference between MF (medium frequency) and HF (high frequency) DSC distress frequencies • The specific HF DSC distress and safety frequencies allocated for ship stations

💭 Think About

• First, list the internationally designated HF DSC distress frequencies, then count how many there are. • Think about whether the MF DSC distress frequency on 2 MHz is included when the question says HF DSC or if it should be excluded. • Consider what a SOLAS/‘compulsory’ vessel that operates beyond sea area A2 must guard continuously on DSC, in addition to VHF Ch 70 and MF DSC.

✅ Before You Answer

• Verify the list of HF DSC distress frequencies (in kHz) from the ITU/Radio Regulations or GMDSS tables. • Confirm whether the MF DSC distress frequency (2187.5 kHz) is part of the count when the question explicitly asks about HF DSC channels. • Check SOLAS/GMDSS watchkeeping rules for compulsory vessels underway to ensure you’re counting only the required HF DSC distress watch channels.