3.1 Voice Mayday Call & Distress Message Structure

3.1 Voice Mayday Call & Distress Message Structure

In maritime radio communications, the Distress Priority represents the highest operational priority level. Understanding when and how to transmit a voice distress call is a fundamental requirement for the RYA Short Range Certificate (SRC) examination. Under the International Telecommunication Union (ITU) Radio Regulations and the International Convention for the Safety of Life at Sea (SOLAS), distress traffic takes absolute precedence over all other radio transmissions.

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Definition of Distress Priority

The distress signal is the spoken word MAYDAY, derived from the French phonetic pronunciation of m'aider ("help me").

Strict Definition: Distress communications may ONLY be initiated when a vessel, aircraft, or person is threatened by grave and imminent danger and requires immediate assistance.

Valid Distress Scenarios vs. Non-Distress Situations

Misuse of the Mayday priority for non-life-threatening situations is a serious offense under UK maritime law and international radio regulations.

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Radio Channel and Transmitter Power Settings

When preparing to transmit a voice Mayday call:

1. VHF Channel 16 (156.800 MHz): Voice distress calls must always be initiated on Channel 16, which is the international distress, safety, and calling channel.
2. Transmitter Power: Ensure the radio's power output is set to High Power (25 Watts). Never use the 1 Watt low-power setting during distress transmissions, as maximum range is essential to reach Coast Radio Stations (CRS) and nearby shipping.

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The Two-Part Voice Distress Transmission

A complete voice distress transmission consists of two separate elements delivered sequentially: the Distress Call followed immediately by the Distress Message.

+------------------------------------------------------------------+
|                      VOICE MAYDAY STRUCTURE                      |
+------------------------------------------------------------------+
| 1. DISTRESS CALL  : MAYDAY (x3) + THIS IS + Vessel Name (x3)    |
|                     + Call Sign + MMSI                           |
| 2. DISTRESS MESSAGE: MAYDAY + Vessel Name + Position             |
|                     + Nature of Distress + Assistance Required  |
|                     + POB + Extra Info + OVER                    |
+------------------------------------------------------------------+

Part 1: The Distress Call

The purpose of the Distress Call is to alert all listening stations on Channel 16 that an urgent distress message is about to follow, and to establish the identity of the vessel in distress.

• MAYDAY MAYDAY MAYDAY
• THIS IS
• BLUE FIN BLUE FIN BLUE FIN (Vessel name spoken 3 times)
• CALL SIGN VICTOR CHARLIE NINE XRAY
• MMSI TWO THREE FIVE NINE EIGHT SEVEN SIX FIVE FOUR

Part 2: The Distress Message

Without pausing for an answer, the operator immediately proceeds with the Distress Message, which contains all vital operational details required by Search and Rescue (SAR) authorities.

• MAYDAY BLUE FIN
• MY POSITION IS FIVE ZERO DEGREES FOUR TWO MINUTES NORTH, ZERO ZERO ONE DEGREE TWO FIVE MINUTES WEST
• SINKING FAST AFTER COLLISION WITH SUBMERGED OBJECT
• REQUIRE IMMEDIATE ASSISTANCE
• FOUR PERSONS ON BOARD
• INFLATING LIFERAFT AND PREPARING TO ABANDON SHIP, EPIRB ACTIVATED
• OVER

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The MIPDANIO Mnemonic for Distress Messages

To ensure no critical information is omitted under extreme stress, RYA candidates are taught the MIPDANIO mnemonic structure:

• M — Mayday: Spoken word MAYDAY followed by the vessel's name.
• I — Identification: Call Sign and 9-digit MMSI number.
• P — Position: Latitude and Longitude (or Bearing and Distance from a fixed mark).
• D — Distress Nature: Specific cause of emergency (e.g., Sinking, Fire, Grounding, Flooding).
• A — Assistance Required: Specific rescue needed (e.g., Immediate evacuation, pumping assistance).
• N — Number of Persons: Persons On Board (POB), including crew and passengers.
• I — Information: Additional safety details (e.g., liferaft deployed, EPIRB active, hull color red).
• O — Over: Proword indicating the transmission is complete and a response is expected.

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Position Reporting Standards

Accurate position reporting is critical for search and rescue operations. Two methods are recognized during RYA SRC exams:

Method A: Latitude and Longitude (Preferred)

Coordinates should be read clearly using standard nautical terms:

• Example: 50°42.5' N, 001°25.2' W
• Voice Script: FIVE ZERO DEGREES FOUR TWO MINUTES POINT FIVE NORTH, ZERO ZERO ONE DEGREE TWO FIVE MINUTES POINT TWO WEST

Method B: Bearing and Distance

Used when exact coordinates are unavailable. The bearing must be specified as Magnetic or True from a prominent, fixed geographical reference point:

• Example: 220° Magnetic, 4 Nautical Miles from Needles Lighthouse
• Voice Script: BEARING TWO TWO ZERO DEGREES MAGNETIC, DISTANCE FOUR NAUTICAL MILES FROM NEEDLES LIGHTHOUSE

Exam Tip: Always state OVER at the end of your distress message. Using OUT is a critical error because OUT means "end of transmission, no answer expected", whereas OVER invites an immediate response.