🔍 Key Concepts

• VHF channel 16 as the international distress, safety, and calling frequency for ships • Difference between radiotelephone (voice on VHF/MF/HF) and radiotelegraph (Morse code on 500 kHz) systems • Which frequencies are associated with maritime services versus aviation (like 121.5 MHz)

💭 Think About

• Which channel or frequency is specifically designated in the Navigation Rules and radio regulations for continuous distress and safety watch by ships with compulsory radiotelephone equipment? • Is 500 kHz used for voice radiotelephone or for Morse code radiotelegraph, and is it still a standard requirement? • Which listed frequency is primarily an aviation emergency frequency rather than a maritime shipboard watch requirement?

✅ Before You Answer

• Confirm which option is described in regulations as the primary maritime distress, safety, and calling channel for voice communications. • Verify whether 500 kHz applies to radiotelephone or to obsolete Morse radiotelegraph services. • Check whether 121.5 MHz is required shipboard, or if it is mainly an aircraft/EPIRB aviation emergency frequency.