International Code of Signals

a collection of signals for international ship-to-ship and ship-to-shore communications. Communication using the international code involves the transmission of combinations of letters by means of signaling equipment.

The first attempt to compile an international code of signals was made by the Board of Trade of Great Britain in 1885. The code was based on 18 flags and contained 70,000 signals. A draft of a new international code prepared by Great Britain was considered at an international conference in Washington in 1889 (it was published in 1897). This code contained 26 flags and provided for transmission of messages using signals with one, two, three, or four flags. At the International Conference on Radiotelegraphy in 1932 a new international code of signals was adopted. It consisted of two volumes. The first was for communication by visual signals (flags, semaphores, and lights), and the second was for encoded radiotelegraph communication. The code provided for communications among ships and airplanes and with the shore (ground).

In 1959 the International Code of Signals was transferred to the jurisdiction of the Inter-Governmental Maritime Consultative Organization (IMCO), which in 1961 established a special subcommittee to prepare a new code of signals. Members of the subcommittee represented 13 countries, including the Soviet Union. The special subcommittee prepared a draft international signal code in nine languages—English, Greek, Spanish, Italian, German, Norwegian, Russian, French, and Japanese—that was put into effect in 1969. It contains about 2,000 signals and is designed primarily to maintain communications in order to secure safety of navigation and protect human life at sea. Signals may be transmitted by all methods of communication, including radiotelephone and radiotelegraph. Each signal has a complete meaning, which makes possible significant simplification of the code and reduction of its size.