Why the Sequence Matters
In a navigational emergency, communications are not an afterthought — they buy you time, summon assistance, and create a record. A candidate at command standard must understand why each action is taken, not simply recite a checklist.
Step 1 — Assess and Decide Before You Transmit
Before keying any radio, the master must determine the nature of the distress: is the vessel in grave and imminent danger requiring immediate assistance (MAYDAY), or is safety threatened but not yet critical (PAN PAN)? Transmitting the wrong signal wastes rescue resources and undermines credibility with rescue coordinators. This judgment is the master's alone.
Step 2 — Initiate Digital Selective Calling (DSC) First
On MF/HF or VHF, the first action is a DSC distress alert on the dedicated DSC controller — VHF Ch 70, MF 2187.5 kHz, HF on the appropriate distress frequency. DSC is the GMDSS primary alerting mechanism: it transmits the vessel's MMSI, nature of distress, position (auto-injected if GPS is interfaced, or manually entered), and time — all without voice, penetrating atmospherics and reaching multiple vessels and coast stations simultaneously. Confirm the GPS interface is feeding live data; if not, position must be entered manually before transmitting.
Step 3 — Follow DSC Alert with Voice MAYDAY
Immediately after the DSC alert, transmit the MAYDAY voice call on the corresponding voice channel — VHF Ch 16, MF 2182 kHz. The format is fixed: MAYDAY spoken three times, vessel name three times, MMSI/call sign, position, nature of distress, persons on board, any other relevant information, OVER. The structured format ensures an RCC or another vessel can act without requesting clarification.
Step 4 — EPIRB Activation
If the vessel is in extremis or communications are failing, manually activate the EPIRB. The 406 MHz signal is received by the Cospas-Sarsat satellite network and routed to the appropriate MRCC within minutes. The EPIRB should already be registered with the MCA with current vessel details — if registration is out of date, responders may act on false information. Automatic float-free activation is a back-up, not a first resort.
Step 5 — SART or AIS-SART
Once evacuation is imminent or a rescue unit is approaching, activate the Search and Rescue Transponder. A SART responds to 9 GHz radar sweeps and paints a line of 12 blips on a rescuer's radar display. An AIS-SART broadcasts a position via AIS. Both guide the final approach — activate early enough to be useful, not after the vessel has sunk.
Step 6 — Maintain a Continuous Watch and Log All Actions
GMDSS carriage requirements for a yacht under 500 GT are determined by sea area (A1–A4). Regardless of fit, once distress is declared, maintain a listening watch on Ch 16 and the DSC distress frequency. Record every transmission — time, frequency, content, acknowledgement received — in the Official Log Book. If communications are acknowledged by an MRCC, follow their instructions; the RCC coordinates the response and the master must not break off contact unilaterally.