2 Each Contracting Government will take all steps necessary to ensure that when intelligence of any of the dangers specified in paragraph 1 is received, it will be promptly brought to the knowledge of those concerned and communicated to other interested Governments.
3 The transmission of messages respecting the dangers specified is free of cost to the ships concerned.
4 All radio messages issued under paragraph 1 shall be preceded by the safety signal, using the procedure as prescribed by the Radio Regulations as defined in regulation IV/2.
Information required in danger messages
The following information is required in danger messages:
1 Ice, derelicts and other direct dangers to navigation
.1 The kind of ice, derelict or danger observed.
.2 The position of the ice, derelict or danger when last observed.
.3 The time and date (Universal Co-ordinated Time) when danger last observed.
2 Tropical cyclones (storms)
.1 A statement that a tropical cyclone has been encountered. This obligation should be interpreted in a broad spirit, and information transmitted whenever the master has good reason to believe that a tropical cyclone is developing or exists in the neighbourhood.
.2 Time, date (Universal Co-ordinated Time) and position of ship when the observation was taken.
.3 As much of the following information as is practicable should be included in the message:
- barometric pressure,* preferably corrected (stating millibars, millimetres, or inches, and whether corrected or uncorrected);
- barometric tendency (the change in barometric pressure during the past three hours);
- true wind direction;
- wind force (Beaufort scale);
- state of the sea (smooth, moderate, rough, high);
*The standard international unit for barometric pressure is the hectopascal (hPa) which is numerically equivalent to the millibar (mbar).
