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Signal Flags

Last modified: 2015-06-13 by peter hans van den muijzenberg
Keywords: signal flags | international | signal code | quarantine | blue peter |
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List of Signal Codes and Proposals

Current uses of Signal Flags

There is an old naval expression to the effect that Eyeball Mark One remains the only reliable instrument of communication and navigation, while all these wonderful electronic gadgets have the nasty habit of leaving one in the lurch just when most needed. My old yeoman of signals instructor when doing my Long Signal Communications Course, used to say that they were all very nice and handy, but the moment the first shot is fired during the next war, electronic silence is immediately imposed by all parties and where would we be without flags then? (He also was of course prejudiced and that was before satellite communications). Although sometimes difficult to see, a colourful piece of bunting fluttering in the wind is much more reliable and attractive. Also, many of the IMO as well as local rules still require certain flags signals to be hoisted while approaching ports, despite the prearrangement of matters per radio - flag Quebec for instance requesting free pratique (health clearance), the pilot flag - flag Hotel, etc.
Andre Burgers, 26 May 2004

They are used quite regularly. Flags provide a continuous signal in a way that a radio transmission cannot. A ship that is disabled in some way, for example, can fly a signal flag continuously, but cannot tie up a radio operator saying over and over again "MV Neversail is disabled; MV Neversail is disabled; MV Neversail is disabled....." A ship flying the BRAVO flag can be seen visually to be handling explosives. Etc.

Upon entering and leaving port, the flying of call sign flags provides harbor authorities the ability to call the ship by call sign: not just "hey you!" but "Harbor police to ALFA YANKEE ONE TWO THREE..."

Navies use flag signals all the time, for example to communicate tactical instructions under radio silence.
Joe McMillan, 26 May 2004

NATO and the Commonwealth navies all use the International Code of Signal flags. I do not know the practice in the former Warsaw Pact navies or the other non-alliance navies, but I suspect that most navies these days use only the ICS flags. What they do have is their own signal code books like the Allied Naval Signal Book (ANSB) used by NATO, which means that although they use the same flags as the ICS do, the meanings attached to the flags, singly or in groups, are quite different. You are right that Navies used to have two flag lockers up until and shortly after WWII, but when NATO was formed in 1949, the Alliance and the Commonwealth introduced the ICS flags for all members with two code books, the ICS for use internally as well as externally, and the ANSB for use only internally.

Closely related for signal communications purposes, a new phonetic code (Alfa, Bravo etc till Zulu, instead of Able, Baker, etc till Zebra) for use on voice radio, was introduced at more or less the same time.
Andries Burgers, 25 October 2006

Blue Peter

[Blue Peter]

I have been searching for info on the origins of signaling flags - those used predominantly by the shipping/naval community, I assume the origin is British Royal Navy in the Napoleonic timeframe, but that is at best a guess.

There appears to be controversy over the source of the name 'Blue Peter' - some say its from 'Blue repeater' (but that is a different flag), and others say its from the French 'partir' - used when leaving harbour.
Rob Bedford, 1999 January 15 and 1999 January 18

Introduced into Royal Navy in the 1750's, as a blue flag with six white balls. Soon after 1756 the white balls were replaced by a white square. "By Rodney's time (c1780) this flag at the mainmast head had become the signal to recall everyone to his ship." Perrin, "British Flags". 1803. "She has had Blue Peter's flag flying at the fore as a signal for sailing." First entry in Oxford English Dictionary. 1862. "The Blue Peter at the foremast head was flying as a summons to the hands on shore to come aboard." Only other entry in OED.

"Blue Repeater"? Looks plausible, but the sense doesn't fit the use. In a signal by flag hoist, there is no such thing as a "repeater" is there? If you want to repeat a flag you use a substitute, and it is described by a number, not a colour.

French "partir"? Haven't heard that one before. I expect some one in France can tell us if they have a name for this flag; "P" in the International Code.

The explanation may lie as much as in the word "blue", as in the word "peter". It is not a blue flag. It is a blue and white flag. Why call it a "blue peter", when there are no "red peters", or "white peters"? I think that it is a corruption of the early official description of the flag, which was the heraldic term "blue pierced white".

The first public commercial code (there were earlier private semi-commercial codes, as used for instance by the East India Company) was the "Code of Signals for the Merchant Service". This was produced in 1817 by Captain Fredrick Marryat, R.N. as the result of problems experienced by ships of the Royal Navy trying to communicate with merchant ships in convoy. It was a numeric code for British ships only, based upon the "Signal Book for Ships of War", which had been introduced for all ships in the Royal Navy in 1799. It was modified with words more appropriate for commercial use.

Ships of other countries began using it, and in 1854, when the 12th edition was published, it was re-titled, "The Universal Code of Signals".

In 1855 the British "Board of Trade" decided that maritime signals needed to be regulated, and authorised the publication in 1857, of the "Commercial Code of Signals". This was an alphabetical code and a considerable improvement on Marryat's code.

It was re-named the "International Code" in about 1870, and revised in 1901 and 1934. There was another revision to the Code in 1969 but I think mainly to sections dealing with electronic communication.
David Prothero, 1999 January 20

It may have been derived from a plain blue flag that was commonly used in the early 1700's, by the Dutch, Danish and Swedish navies, as a signal that a ship was preparing to sail. It is unlikely to have been used by the Royal Navy, as a plain blue flag was a command flag flown by an admiral of the blue squadron. In the 19th century when the "blue flag with a white square in the centre" had been widely adopted as a signal of departure, it was commonly known as "Blue Peter" in north European languages, but not in French or Spanish.

Marryat (who was also a novelist and wrote "Mr Midshipman Easy") based his 1817 Merchant Service Code on Naval Codes that had been introduced in about the middle of the 18th century, and gradually improved over the following years. Before that time signals had been made with ordinary ensigns, jacks, pennants and standards, rather than flags designed specifically for the purpose. The position in the ship where the flag was hung, was as significant as the flag itself. The early codes were often two flag hoists, based on a table of messages set in a grid, the upper flag indicating the column of the grid and the lower flag the row. These were replaced by proper numeric codes with each one of ten flags, indicating one of the numbers 0 to9. Additional flags were used to indicate beginning and end of messages, substitutes, hundreds and thousands.

The flags could only indicate a number which related to a pre-determined message, and the next improvement was the vocabulary code. In this system numbers could indicate a single word or phrase, so that sentences could be built up from scratch. Finally the number of flags was increased so that most letters of the alphabet could be signaled separately in order to build-up uncommon words. The numeric code continued in use alongside the vocabulary code, as it was a more efficient way of signaling commonly used messages.

Marryat's code was numeric and used the Union Jack as one of the signal flags. This had the result that British merchant ships were able to fly the Union Jack as part of a signal hoist, but not as an ensign or jack. The Admiralty objected to this and in the fourth edition of Marryat's code published in 1826, a white bordered Union Jack replaced the Union Jack. Some interesting terms used in correspondence between Marryat and the Admiralty; "New Signal Jack" was the Union Jack with a white border; "His Majesty's Jack" was the Union Jack; and "the National Red Ensign", was the plain Red Ensign, which at the time was still a naval flag as well as the merchant flag.

 One peculiarity of the 1857 code introduced by the Board of Trade, was that although it had flags representing letters, there were only 18 of them, B to W and no vowels; so that objectionable three and four letter words could not be signaled by rude sailors.

The 1901 code introduced the full set of letters and the 1934 code added numbers.
David Prothero, 1999 February 03

I found a reference to the Blue Peter in the book Naval Ceremonies, Customs, and Traditions 4th Ed. by William P. Mack and Royal W. Connell. It reads:

BLUE PETER. A flag, "blue pierced with white," was used in the British Navy from 1777 as a general recall flag. In a quarter of a century the term "blue peter" was used by all to designate this flag. Civilians knew its significance, for merchant ships and convoys in the French wars would not sail until the escorting man-of-war hoisted the blue peter for passengers to come aboard.

There is on record a historic piece of doggerel, autographed "Emma," written when Nelson sailed in 1801:

Silent grief and sad forebodings
(Lest I ne'er should see him more)
Fill my heart when gallant Nelson
Hoists blue peter at the fore.

The "Blue Peter" was at the time of the War of 1812 flown at the fore preparatory to sailing.
Mike White, 22 October 1999

See also: Vexillology

White Peter, Red Peter

With reference to a race for the Royal Nova Scotia Yacht Squadron, it was noted "If it's necessary during a Race to shorten the
course, the signal flag denoting the race hoisted under the White Peter ... shall show that the Race is to finish with the round about to be completed ..."


Now we may add that there is in fact a White Peter. From other references on the web this would seem to be the name for the complement of the Blue Peter: white with a centred blue rectangle: S. I expect the name was derived from that of the Blue Peter.
Peter Hans van den Muijzenberg, 11 April 2015

Describing signal flags of the Royal Navy in ‘Flags of the World’, 1915, William Gordon wrote;
“...; the red peter with a blue edging, now W of the International Code, for A ...”
“...; the white peter, now the S of the International Code, for V ...”
“...; the red peter for 9; ...” xf~rhs2.html
David Prothero, 11 April 2015

Substitute Flags

The use of substitutes is to enable the same signal flag, either alphabetical flag or numeral pennant, to be repeated one or more times in the same group, in case only one set of flags is carried on board. The first substitute always repeats the uppermost signal flag of that class of flags which immediately precedes the substitute. The second substitute always repeats the second and the third substitute repeats the third signal flag, counting from the top of that class of flags which immediately precedes them. No substitute can ever be used more than once in the same group.
Phil Nelson, 25 January 2010


Archives & Collections Society of Picton, Ontario, Canada

Various signal flag plates are shown and can be enlarged by clicking:

  1. Codice Internazionale Dei Segnali, Tipografia Del Lloyd Austro-Ungarico, Trieste, 1882 Plate "xv del Codice internazionale dei segnali" no vowels or numerics; "X" "Y" "Z" absent
  2. Standard Seamanship for the Merchant Service, Riesenberg, Felix, C.E.D., Van Nostrand Company, 1922 "International Code Flags" p559. Changes include "F" and "L"
  3. Manual of Seamanship, Government of Canada, Ottawa, 1937 "Alphabetical and Numeral Flags Used in Naval Signaling", Plate 9
  4. Manual of Seamanship, Government of Canada, Ottawa, 1937 "Special Flags Used in Naval Signaling", Plate 10
  5. Manual of Seamanship, Government of Canada, Ottawa, 1937 "Numbered & Special Pendants Used in Naval Signaling", Plate 11
  6. Manual of Seamanship, Government of Canada, Ottawa, 1937 "Flags and Pendants Used in the International Code", facing p58. Changes include "C" "D" "E" "F" and "G"
  7. Manual of Seamanship, Government of Canada, Ottawa, 1937 "Numeral Pendants" "Substitutes" "Code and Answering Pendant", facing page 58
  8. Manual of Seamanship Volume II, Government of Canada, Ottawa, 1951 "Other Flags and Pennants Used in Naval Signaling", plate 3. All Naval numeral flags have changed.
  9. Piloting Seamanship & Small Boat Handling, Charles F Chapman, Motor Boating Magazine, 1956 "Special Navy Flags and Pennants", p. 384. Changes include "church" flag, and addition of "fourth sub" flag

Green as a colour in signal flags is, to my untrained eye, unusual.
Jan Mertens, 17 October 2004

Some photos of signal flag charts can be found:

Elias Granqvist, 20 May 2008


The following question generated the responses that follow:

Do you know of the ICS sailing/shipping flag that means "under way", "leaving port", or more unprofessionally "outward bound"?
Geoffrey Godfrey, 29 April 2007

According to Smith (Flags through the Ages & Across the World) [smi75b] the "Blue Peter" (Papa) means "About to Sail". None of the flags is indicated as signifying "Under Way".
Albert S. Kirsch, 30 April 2007

In the list of single meanings of the ICS there are several flags with meanings pertaining to the maneuvering of vessels. Flag M flown singly indicates: My vessel is stopped and making no way through the water. Flag S means: I am operating astern propulsion. Flag T means: Keep clear of me. I am engaged in pair trawling. There is, however, no actual signal indicating that a vessel is underway and making way through the water in normal circumstances. The only signal which can be read as meaning that a vessel is about to leave port would be Flag G meaning: I require a pilot. There is a signal for icebreakers, also Flag G when in an ice channel, meaning: I am going ahead, follow me. This is, however, only applicable between icebreakers and assisting vessels.

This is a case where the absence of a signal to the contrary indicates the fact that a vessel is moving, or free to move, through the water. A ship alongside a quay is obviously not underway and need not signal the fact although the flying of a jack may be read as confirmation of this fact, but not all merchant vessels do so - only warships will usually fly a jack when secured to a quay, anchor or a buoy. A vessel at anchor or at a mooring buoy, must hoists a black ball on the forestay, or where best seen in the forepart of the vessel. I presume that it was assumed by the compilers of the code, that any seaman will, when conditions of visibility are conducive to the observation of signals, also be able to note that a vessel is making way through the water by observing her bearing movement and that such a signal is therefore unnecessary.

When visibility is so bad that vessels cannot see each other at a safe distance, they sound the appropriate fog signals for vessels underway and making way, or underway but not making way, or at anchor or moored, from the Rules of the Road (International Rules for the Prevention of Collisions at Sea), on their foghorns, or sirens or ships bells. It is to be noted that any ship not attached to the land in some manner is considered to be underway even though it might not actually be moving through the water. Thus the distinction in the Rules between underway and making way, and underway but not making way.
Andries Burgers, 30 April 2007

From my long-ago US Navy training, I recall that the Navy uses "Mike" and the "Speed" pennant to indicate that the vessel is moving at a given speed. For example, the hoist "M/Speed pennant/One/Five" means "My speed is 15 [knots]." The numbers here are represented by the rectangular naval number flags rather than the ICS pennants. I have photo here in my office of the battleship USS Iowa making such a signal during her recommissioning trials back in 1984.
Peter Ansoff, 30 April 2007

The speed pennant and numeral flags both belong to the NATO signal code and they do not exist in the ICS. It is also not necessary to use Flag Mike when using the speed pennant. A NATO or Commonwealth warship (and a few other Allied navies) would simply hoist Speed followed by numeral flags One and Five to indicate that the ship flying the signal is making 15 knots. I do not know whether there has been an amendment to the rules of signal usage or slightly different rules in the US Navy, but to use Flag Mike as well, could have been confusing, because Mike has a separate single meaning in the NATO code (which I do not recall for the moment) and combining that with Speed 15 might have meant something entirely different. In a voice transmission over tactical radio, the signal would also have been transmitted as: Callsign de Callsign Speed 15 Out.
Andries Burgers, 30 April 2007

Situation Normal

Is there a combination of signal flags that denotes "situation normal"?

As far as I am aware it is the absence of any signal flags which indicates "situation normal."
Christopher Southworth, 26 April 2008

My copy of ICS (2005 Edition) is the latest I believe and Chris is correct because there is no signal or signal group which tells the good news. The custom at sea is that signalling is kept to a minimum and if I don't say anything it means I have nothing to say. There is nothing so annoying at sea than a ship chattering like a fishwife whether by flags, lights or radio, and he usually ends up being ignored.
Andries Burgers, 26 April 2008

Unusual Signals

A very good source for signals made by the Royal Navy during its history, is the book by Captain Jack Broom RN entitled Make a Signal. It not only includes signals made during significant events in Royal Navy history (including Jutland), but also a section on some of the funny signals that have been exchanged between ships, flag officers etc. One of my favourites is the story (no doubt apocryphal) of an Royal Navy destroyer meeting up with an US destroyer in mid-Atlantic during World War II. The US ship is flying: Church pennant over Interrogative. Not having such a signal in its signal book, the Royal Navy ship asked by light what the meaning was. The US destroyer replied: GOD WHERE AM I?
Andries Burgers, 19 January 2008

I've got a copy of Captain Jack Broom's Make another signal; the first forty pages are a general history of signalling from the battle of Salamis; then a short section on flags; the third section is Royal Navy history through signals, from 1793 to 1949; and the final section consists of the humorous ones. The approach in the first two sections is pretty light and popular.

As to their possible apocryphal nature, Broome served in the Royal Navy from 1914 to 1947, so would have seen some first hand, and have been told about many more by fellow officers. Many involve the quotation of verses of the Bible, and quite a few officers maintained their own list of passages which could be used as appropriate. We have one in the Flag Institute Library that belonged to the late Barrie Kent.

Some random examples from Broome:

  • A cruiser in a North Sea fog during the First World War sent the following: 'Enemy battleship bearing NNE distance 2 miles. Am preparing to ram.' It then followed with a second signal a couple of minutes later: 'Cancel my last signal. Battleship turns out to be a lighthouse'.
  • A destroyer to a trawler flying an unintelligible signal: 'What is the significance of the signal you are flying?' The trawler replied: 'Regret I do not know. Flags smelt of fish.'
  • A submarine returning from a patrol during the Second World War sent simply to the flotilla captain: 'Psalm 17 v.4' [Concerning the works of men by the word of thy lips I have kept me from the paths of the destroyers]
  • And a final modern example from a NATO frigate on exercise to a Soviet trawler that had been shadowing the exercise: 'Do you require refueling?'. Soviet trawler: 'Not if your exercise finishes on time.'

Ian Sumner, 20 January 2008