International Code of Signals

The International Code of Signals (ICS) is the standardized system of single and multi-letter signal codes, flags, and Morse groups for safety and distress communication between vessels and shore stations when language barriers exist. SOLAS V/21 requires every ship carrying a radio installation under the Convention to carry the current ICS as amended by IMO. The Code covers distress, medical advice, navigation, and maneuvering messages. It maps directly onto flag hoists, flashing light, sound, and radiotelephony. Radio-fitted ships also carry IAMSAR Manual Volume III under the same regulation. The ICS is published by IMO and checked at survey as a mandatory carriage item.