^{This page is part of © FOTW Flags Of The World website}

International Code of Signals

Maritime Signal Flags

See also:

Signal Flags
Maritime Signal Flag History
International Code of Signals (Overview)
International Code of Signals (Numeric)
International Code of Signals (Miscellaneous)
Extensions to the International Code of Signals
FOTW Vexillological Reference
FOTW Topical Index

Individually, each flag has a specific meaning. Below are the meanings from the 1951 Admiralty Manual of Seamanship and the newer meanings from the 1969 RYA Flags and Signals complied by David Prothero

ICS Letter A (Alpha)

image by António Martins-Tuválkin, 17 May 2025
Alpha; I am undergoing a speed trial, became: I have a diver down; keep well clear at slow speed.

ICS Letter B (Bravo)

image by António Martins-Tuválkin, 17 May 2025
Bravo; I am taking in or discharging explosives: became, I am taking in, or discharging, or carrying dangerous goods.

ICS Letter C (Charlie)

image by Antonio Martins
Charlie; Yes (Affirmative): became, Yes (Affirmative or 'The significance of the previous group should be read in the affirmative').

ICS Letter D (Delta)

image by Antonio Martins

ICS Letter E (Echo)

image by Antonio Martins
Echo; I am directing my course to starboard: became, I am altering my course to starboard.

ICS Letter F (Foxtrot}

image by António Martins-Tuválkin, 17 May 2025

ICS Letter G (Golf)

image by Antonio Martins
Golf; New additional meaning; (When made by fishing vessels operating in close proximity on the fishing grounds it means 'I am hauling nets')

ICS Letter H (Hotel)

image by Antonio Martins

ICS Letter I (India)

image by António Martins-Tuválkin, 17 May 2025
India; I am directing my course to port: became, I am altering my course to port

ICS Letter J (Juliet)

image by Antonio Martins
Juliet; I am going to send a message by semaphore: became, I am on fire and have dangerous cargo on board; keep well clear of me.

ICS Letter K (Kilo)

image by Antonio Martins
Kilo; You should stop your vessel instantly became, I wish to communicate with you.

ICS Letter L (Lima)

image by Antonio Martins
Lima; You should stop - I have something important to communicate: became, You should stop your vessel instantly.

ICS Letter M (Mike)

image by António Martins-Tuválkin, 17 May 2025
Mike; I have a doctor on board: became My vessel is stopped and making no way through the water.

ICS Letter N (November)

image by Antonio Martins
November; No (Negative): became, No (Negative or 'The significance of the previous group should be read in the negative').

ICS Letter O (Oscar)

image by António Martins-Tuválkin, 21 June 2025

ICS Letter P (Papa)

image by Antonio Martins
Papa; In harbour the same. At sea, Your lights are out or burning badly: became, when used by fishing vessels to mean, 'My nets have come fast upon an obstruction'.

ICS Letter Q (Quebec)

image by Antonio Martins
The solid yellow flag was used to indicate quarantine before it was made the flag for Q. Also, it's worth noting that display of the yellow Q flag today means that the ship does not have disease aboard; it signifies "I request free pratique," which means I ask that the authorities in the port give me a clean bill of health.
Joe McMillan, 15 February 2005

See also:

Quarantine flag

ICS Letter R (Romeo)

image by Phil Nelson
Romeo; The way is off my ship - you may feel your way past me. (No current meaning available)

ICS Letter S (Sierra}

image by Antonio Martins
Sierra; My engines are going full speed astern: became, My engines are going astern.

ICS Letter T (Tango)

image by Antonio Martins
Tango; Do not pass ahead of me: became, Keep clear of me; I am engaged in pair trawling.

ICS Letter U (Uniform)

image by Antonio Martins
Uniform; You are standing into danger: became, You are running into danger.

ICS Letter V (Victor)

image by António Martins-Tuválkin, 17 May 2025

ICS Letter W (Whiskey)

image by Antonio Martins

ICS Letter X (X-Ray)

image by Phil Nelson

ICS Letter Y (Yankee)

image by António Martins-Tuválkin, 17 May 2025
Yankee; I am carrying mails: became, I am dragging my anchor.

ICS Letter Z (Zulu)

image by António Martins-Tuválkin, 17 May 2025
Zulu; To be used to address or call shore stations: became, I require a tug. or, when made by fishing vessels operating in close proximity on the fishing grounds it means, 'I am shooting nets'.