INTERNATIONAL CODE OF

SIGNALS
(ICS)
 EXPLANATION AND GENERAL
REMARKS
• 1. The purpose of the International Code of Signals is to provide
ways and means of communication in situations related essentially
to safety of navigation and persons, especially when language
difficulties arise. In the preparation of the Code, account was taken
of the fact that wide application of radiotele- phony and
radiotelegraphy can provide simple and effective means of
communication in plain language whenever language difficulties do
not exist.
• 2. The signals used consist of:
(a) Single-letter signals allocated to significations which are
very urgent, important, or of very common use;
(b) Two-letter signals for General Signal Code, Chapter 2, Pages
25 through 102;
(c) Three-letter signals beginning with “M” for Medical Signal
Code, Chapter 3, pages 107 through 132.
• 3. The Code follows the basic principle that each signal should have a
complete meaning. This principle is followed throughout the Code; in
certain cases complements are used, where necessary to supplement the
available groups.
• 4. Complements express:
(a) Variations in the meaning of the basic signal.
Examples: “CP” = “I am (or vessel indicated is) proceeding to your
assistance.”
“CP 1” = “SAR aircraft is coming to your assistance.”
(b) Questions concerning the same basic subject or basic signal.
Examples: “DY” = “Vessel (name or identity signal) has sunk in lat . . . long. . . ”;
“DY 4” = “What is the depth of water where vessel sank?”
(c) Answers to a question or request made by the basic signal.
Examples: “HX” = “Have you received any damage in collision?”
“HX 1” = “I have received serious damage above the waterline.”
(d) Supplementary, specific or detailed information.
Examples: “IN” = “I require a diver.” “IN 1” = “I require a diver to clear
propeller.”
• 5. Complements appearing in the text more than once
have been grouped in three tables. These tables should
be used only as and when specified in the text of the
signals.
• 6. Text in brackets indicates:
(a) an alternative, e.g.:“. . . (or survival craft). . . ”;
(b) information which may be transmitted if it is
required or if it is available, e.g.: “. . . (position to
be indicated if necessary)”;
(c) an explanation of the text.
• 7. The material is classified according to subject and
meaning. Extensive cross referencing of the signals in
the right-hand column is used to facilitate coding.
 DEFINITIONS
For the purpose of this Code the following terms shall have the
meanings defined below:
• Visual signaling is any method of communication, the transmission
of which is capable of being seen.
• Sound signaling is any method of passing Morse signals by means
of siren, whistle, foghorn, bell, or other sound apparatus.
• Originator is the authority who orders a signal to be sent.
• Identity signal or call sign is the group of letters and figures
assigned to each station by its administration.
• Station means a ship, aircraft, survival craft, or any place at which
communications can be effected by any means.
• Station of origin is that station where the originator submits a
signal for transmission, irrespective of the method of
communication employed.
• Transmitting station is the station by which a signal is actually
being made.
• Addressee is the authority to whom a signal is addressed.
• Station of Destination is that station in which the signal is
finally received by the addressee.
• Receiving station is the station by which a signal is actually
being read.
• Procedure denotes the rules drawn up for the conduct of
signaling.
• Procedure signal is a signal designed to facilitate the conduct
of signaling. (See Chapter 1, Section 10, Pages 16, 19, and 20.)
• Time of origin is the time at which a signal is ordered to be
made.
• Group denotes more than one continuous letter and/or
numeral which together compose a signal.
• A numeral group consists of one or more numerals.
• A hoist consists of one or more groups displayed from a single
halyard. A hoist or signal is said to be at the dip when it is
hoisted about half of the full extent of the halyards. A hoist or
signal is said to be close up when it is hoisted to the full extent
of the halyards.
• Tackline is a length of halyard about 2 m (6 ft.) long, used to
separate each group of flags.
 SINGLE LETTER SIGNALS
• A I have a diver down; keep well clear at slow
speed.
• *B I am taking in, or discharging, or carrying
dangerous goods.
• *C Yes (affirmative or “The significance of the
previous group should be read in the
affirmative”).
• *D Keep clear of me; I am maneuvering with
difficulty.
• *E I am altering my course to starboard.
• F I am disabled; communicate with me.
• *G I require a pilot. When made by fishing vessels
operating in close proximity on the fishing grounds it
means: “I am hauling nets”.
• *H I have a pilot on board.
• *I I am altering my course to port.
• J I am on fire and have dangerous cargo on
board: keep well clear of me, or I am leaking
dangerous cargo.
• K I wish to communicate with you.
• L You should stop your vessel instantly.
• M My vessel is stopped and making no way
through the water.
• N No (negative or “The significance of the
previous group should be read in the
negative”). This signal may be given only
visually or by sound. For voice or radio
transmission the signal should be “NO”.
• O Man overboard.
• P In harbor.—All persons should report on
board as the vessel is about to proceed to
sea.
At sea.—It may be used by fishing vessels to
mean: “My nets have come fast upon
an obstruction”. It
may also be used as a sound to mean: “I
require a pilot”.
• Q My vessel is “healthy” and I request free
pratique.
• *S I am operating astern propulsion.
• *T Keep clear of me; I am engaged in pair trawling.
• U You are running into danger.
• V I require assistance.
• W I require medical assistance.
• X Stop carrying out your intentions and watch for my
signals.
• Y I am dragging my anchor.
• *Z I require a tug. When made by fishing vessels
operating in close proximity on the fishing grounds it
means: “I am shooting nets”.

Notes:
1.Signals of letters marked by an asterisk (*) when made by sound may
only be made in compliance with the requirements of the
International Regulations for Preventing Collisions at Sea, 1972.
2.Signals “K” and “S” have special meanings as landing signals for small
boats with crews or persons in distress. (International Convention for
the Safety of Life at Sea, 1974, Chapter V, Regulation 16.)
 SINGLE LETTER SIGNALS WITH
COMPLEMENTS
• A with three numerals AZIMUTH
or
BEARING.
• C with three numerals COURSE.
• D with two, four, or six numerals DATE.
• G with four or five numerals LONGITUDE
(the last two numerals
denote minutes and the
rest degrees).
• K with one numeral I wish to
COMMUNICATE
with you by . . .
(Complements Table 1, Chapter 2,
Section 10, Page 102).
• L with four numerals LATITUDE (the
first two denote
degrees and the rest
minutes).
• R with one or more numerals DISTANCE in
nautical miles.
• S with one or more numerals SPEED in knots.
• T with four numerals LOCAL TIME
(the first two denote
hours and the rest
minutes).
• V with one or more numerals SPEED in
kilometers per hour.
• Z with four numerals UTC (the first two
denote hours and
the rest minutes).
• Z with one numeral To CALL or
ADDRESS shore
visual stations
(Numeral to be
approved by local
port authority).