The transmission of information regarding ice, derelicts, tropical storms or any other direct danger to navigation is obligatory. The form in which the information is sent is not obligatory. It may be transmitted either in plain language (preferably English) or by means of the International Code of Signals (Wireless Telegraphy Section). It should be issued CQ to all ships, and should also be sent to the first point of the coast to which communication can be made with a request that it be transmitted to the appropriate authority.
All messages issued under Article 34 of the present Convention will be preceded by the safety signal TTT followed by an indication of the nature of the danger, thus: TTT Ice; TTT Derelict, TTT Storm; TTT Navigation.
The following information is desired, the time in all cases being Greenwich Mean Time:—
Ice, Derelicts and other Direct Dangers to Navigation.
the kind of ice, derelict or danger observed;
the position of the ice, derelict or danger when last observed.
the time and date when the observation was made.
Tropical Storms.—(Hurricanes in the West Indies, Typhoons in the China Seas, Cyclones in Indian waters, and storms of a similar nature in other regions.)
A Statement that a Tropical Storm 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 storm exists in his neighbourhood.
Meteorological Information.—In view of the great assistance given by accurate meteorological data in fixing the position and movement of storm centres, each shipmaster should add to his warning message as much of the following meteorological information as he finds practicable:—
barometric pressure (millibars, inches or millimetres);
change in barometric pressure (the change during the previous two to four hours);
wind direction (true not magnetic);
wind force (beaufort or decimal scale);
state of the sea (smooth, moderate, rough, high);
swell (slight, medium, heavy) and the direction from which it comes.
When barometric pressure is given the word “millibars,” “inches” or “millimetres,” as the case may be, should be added to the reading, andit should always be stated whether the reading is corrected or uncorrected.
When changes of the barometer are reported the course and speed of the ship should also be given.
All directions should be true, not magnetic.
Time and Date and Position of the Ship.—These should be for the time and position when the meteorological observations reported were made and not when the message was prepared or despatched. The time used in all cases should be Greenwich Mean Time.
Subsequent Observations.—When a master has reported a tropical storm it is desirable, but not obligatory, that other observations be made and transmitted at intervals of three hours, so long as the ship remains under the influence of the storm.
Ice.
TTT Ice. Large berg sighted in 4605 N., 4410 W., at 0800 GMT. May 15.
Derelict.
TTT Derelict. Observed derelict almost submerged in 4006 N., 1243 W., at 1630 GMT. April 21.
Danger to Navigation.
TTT Navigation. Alpha lightship not on station. 1800 GMT. January 3.
Tropical Storm.
TTT Storm. Experiencing tropical storm. Barometer corrected 994 millibars, falling rapidly. Wind NW., force 9, heavy squalls. Swell E. Course ENE., 5 knots. 2204 N., 11354 E. 0030 GMT. August 18.
TTT Storm. Appearances indicate approach of hurricane. Barometer corrected 29.64 inches falling. Wind NE., force 8. Swell medium from NE. Frequent rain squalls. Course 35°, 9 knots. 2200 N., 7236 W. 1300 GMT. September 14.
TTT Storm. Conditions indicate intense cyclone has formed. Wind S. by W. force 5. Barometer uncorrected 753 millimetres, fell 5 millimetres last three hours. Course N. 60 W., 8 knots. 1620 N., 9302 E. 0200 GMT. May 4.
TTT Storm. Typhoon to south-east. Wind increasing from N. and barometer falling rapidly. Position 1812 N., 12605 E. 0300 GMT. June 12.