PUB. 102

International Code of Signals

As adopted by the Fourth Assembly of the Inter-Governmental Maritim

Consultative Organization in 1965

For Visual, Sound, and Radio Communications

United States Edition, 1969

(Revised 2003)

Prepared and published by the

NATIONAL IMAGERY AND MAPPING AGENCY

Bethesda, Maryland

© COPYRIGHT 2003 BY THE UNITED STATES GOVERNMENT

NO COPYRIGHT CLAIMED UNDER TITLE 17 U.S.C.

For sale by the Superintendant of Documents, U.S. Government Printing Office

Internet: bookstore.gpo.gov Phone: toll free (866) 512-1800; DC area (202) 512-1800

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PREFACE

Pub 102, the 1969 edition of the International Code of Signals, became effective on 1 April 1969, and at 

superseded H.O. Pubs. 103 and 104, International Code of Signals, Volumes I and II. All signals are contained in 

volume suitable for all methods of communication.

The First International Code was drafted in 1855 by a Committee set up by the British Board of Trade. It containe

signals using eighteen flags and was published by the British Board of Trade in 1857 in two parts; the first co

universal and international signals and the second British signals only. The book was adopted by most seafaring 

This early edition was revised by a Committee set up in 1887 by the British Board of Trade. The Committee’s p

were discussed by the principal maritime powers and at the International Conference in Washington in 1889. As 

many changes were made. The Code was completed in 1897 and was distributed to all maritime powers. That e

the International Code of Signals, however, did not stand the test of World War I.

The International Radiotelegraph Conference at Washington in 1927 considered proposals for a new revision of 

and decided that it should be prepared in seven languages, namely in English, French, Italian, German, Japanese

and in one Scandinavian language which was chosen by the Scandinavian Governments to be the Norwegian langu

new edition was completed in 1930 and was adopted by the International Radiotelegraph Conference held in M

1932. The new Code was compiled in two volumes, one for use by visual signaling and the other by radiotelegraph

and phrases applicable to aircraft were introduced in Volume II together with a complete Medical Section and a 

accelerating the granting of pratique. The Medical Section and the pratique signals were prepared with the assist

by the advice of the Office International d’Hygiene Publique. The Code, particularly Volume II, was primarily inte

use by ships and aircraft and, via coastal radio stations, between ships or aircraft and authorities ashore. A certain 

of signals were inserted for communications with shipowners, agents, repair yards, etc. The same Conference 

1932) established a Standing Committee to review the Code, if and when necessary, to give guidance on questio

and procedure, and to consider proposals for modifications. Secretarial duties were undertaken by the Governme

United Kingdom. The Standing Committee met only once in 1933 and introduced certain additions and amendm

The Administrative Radio Conference of the International Telecommunication Union suggested in 1947 

International Code of Signals should fall within the competence of the Inter-Governmental Maritime Con

Organization (IMCO). In January 1959, the First Assembly of IMCO decided that the Organization should assum

functions then being performed by the Standing Committee of the International Code of Signals. The Second Ass

1961 endorsed plans for a comprehensive review of the International Code of Signals intended to meet the pre

requirements of mariners. A Subcommittee of the Maritime Safety Committee of the Organization was established 

the Code, to prepare it in nine languages, namely the original seven (English, French, Italian, German, Japanese, 

and Norwegian) together with Russian and Greek, and to consider proposals for a new radiotelephone Code and it

to the International Code of Signals. The Subcommittee consisted of representatives of the following countries: A

Germany, France, Greece, Italy, Japan, Norway, Russian Federation, United Kingdom, and the United States of 

The following international governmental and nongovernmental organizations contributed to, and assisted 

preparation of the revised Code: the International Atomic Energy Agency, the International Civil Aviation Orga

the International Labor Organization, the International Telecommunication Union, the World Meteorological Orga

the World Health Organization, the International Chamber of Shipping, the International Confederation of Fr

Unions, and the International Radio Maritime Committee.

The Subcommittee completed the revision of the Code in 1964, taking into account Recommendation 42 of 

Conference on Safety of Life at Sea and Recommendation 22 of the Administrative Radio Conference, Geneva 1

Code was adopted by the Fourth Assembly of IMCO in 1965.

The revised Code is intended to cater primarily for situations related essentially to safety of navigation and 

especially when language difficulties arise. It is suitable for transmission by all means of communication, i

radiotelephony and radiotelegraphy, thus obviating the necessity for a separate radiotelephone Code and dispen

Volume II for Radiotelegraphy. The revised Code embodies the principle that each signal has a complete meanin

leaves out the vocabulary method which was part of the old Code. The Geographical Section, not being co

essential, was omitted. By these means it was possible to reduce considerably the volume of the Code and 

simplicity.

Changes and corrections for this product will appear in the NIMA weekly Notice to Mariners and must be applie

it current. Users should refer information and comments to: MARITIME SAFETY INFORMATION DIVISION, 

NATIONAL IMAGERY AND MAPPING AGENCY, 4600 SANGAMORE ROAD, BETHESDA MD 20816-5