🔍 Key Concepts

• Distress procedures in the Global Maritime Distress and Safety System (GMDSS) and older radiotelegraph systems • Difference between distress call and distress message • Use and meaning of auto-alarm signals, SOS, and MAYDAY

💭 Think About

• Think about which method and frequency range the question is referring to: is it radiotelegraph on 500 kHz, modern VHF voice, or something else? • Ask yourself what, historically, was used to automatically trigger receivers on ships before the actual distress content was sent. • Consider whether the question is about the spoken/encoded distress signal itself or about a special alert that comes before it.

✅ Before You Answer

• Identify whether the question is specifically about radiotelegraph on 500 kHz or general voice procedures. • Recall which signal was used to trigger auto-alarm receivers on ships in the old 500 kHz system. • Verify which of the options describes a preparatory or alert signal that comes before the distress call, rather than being the distress call itself.