1921–42
The RAF’s own alphabet
The Royal Air Force used at least two different alphabets; the one it used from 1921 to 1942 began Ace, Beer, Charlie.
University of York ↗
HISTORY
From Amsterdam
From Amsterdam
to Alfa.
NATO says the alphabet was created in 1956 and helps NATO forces communicate with each other clearly and quickly. NATO ↗ It took several alphabets to get there.
1927
The ITU’s first alphabet
In 1927 the ITU produced the first phonetic alphabet to be recognised internationally, mostly using the names of cities and countries.
NATO ↗1932
1941
Able Baker
In 1941 the United States adopted the Joint Army/Navy “Able Baker” alphabet across all its military branches; two years later the Royal Air Force decided to use it too.
NATO ↗1951
IATA’s alphabet
A version mixing sounds common to English, French and Spanish was proposed by IATA and came into effect on 1 November 1951, for civil aviation only.
NATO ↗Mid-1950s
A NATO review
NATO’s review of the IATA alphabet in the mid-1950s was led by the United Kingdom and the United States.
NATO ↗8 April 1955
NATO decides
On 8 April 1955, NATO’s Standing Group advised that the alphabet would be made effective for NATO use whether or not ICAO approved it.
NATO ↗1956
The alphabet we use today
On 21 February 1956, NATO Allies were told the new phonetic alphabet was to be made effective in NATO on 1 March 1956.
NATO ↗Later
The ITU adopts it
NATO says the ITU formally adopted the alphabet a few years later, and that it became known as “the NATO phonetic alphabet” because NATO Allies led the final revision.
NATO ↗Nectar or November?
NATO’s first proposal took the IATA alphabet and changed five words: Coca, Metro, Nectar, Union and eXtra. NATO ↗
The NATO proposal kept debating the word for N, Nectar or November; the final alphabet used November. NATO ↗ NATO says ICAO approved the alphabet, with November as the code word for N. NATO ↗
Six alphabets side by side
| Letter | RAF 1921–42 | ITU 1927 | ITU 1932 | Able Baker 1941 | IATA 1951 | 1956 to today |
|---|---|---|---|---|---|---|
| A | Ace | Amsterdam | Amsterdam | Able | Alfa | Alfa |
| B | Beer | Baltimore | Baltimore | Baker | Bravo | Bravo |
| C | Charlie | Canada | Casablanca | Charlie | Coca | Charlie |
| D | Don | Denmark | Danemark | Dog | Delta | Delta |
| E | Edward | Eddystone | Edison | Easy | Echo | Echo |
| F | Freddie | Francisco | Florida | Fox | Foxtrot | Foxtrot |
| G | George | Gibraltar | Gallipoli | George | Gold | Golf |
| H | Harry | Hanover | Havana | How | Hotel | Hotel |
| I | Ink | Italy | Italia | Item | India | India |
| J | Johnnie | Jerusalem | Jerusalem | Jig | Juliett | Juliett |
| K | King | Kimberley | Kilogramme | King | Kilo | Kilo |
| L | London | Liverpool | Liverpool | Love | Lima | Lima |
| M | Monkey | Madagascar | Madagascar | Mike | Metro | Mike |
| N | Nuts | Neufchatel | New York | Nan | Nectar | November |
| O | Orange | Ontario | Oslo | Oboe | Oscar | Oscar |
| P | Pip | Portugal | Paris | Peter | Papa | Papa |
| Q | Queen | Quebec | Quebec | Queen | Quebec | Quebec |
| R | Robert | Rivoli | Roma | Roger | Romeo | Romeo |
| S | Sugar | Santiago | Santiago | Sugar | Sierra | Sierra |
| T | Toc | Tokio | Tripoli | Tare | Tango | Tango |
| U | Uncle | Uruguay | Upsala | Uncle | Union | Uniform |
| V | Vic | Victoria | Valencia | Victor | Victor | Victor |
| W | William | Washington | Washington | William | Whiskey | Whiskey |
| X | X-ray | Xantippe | Xanthippe | X-ray | eXtra | X-ray |
| Y | Yorker | Yokohama | Yokohama | Yoke | Yankee | Yankee |
| Z | Zebra | Zululand | Zürich | Zebra | Zulu | Zulu |
Why use code words at all?
THE PROBLEM
Letters said the ordinary way (“Ay”, “Bee”, “Sea”) can sound alike and be misheard, which is why longer code words are used. University of York ↗
WHY IT RARELY CHANGES
A NATO memo quoted by the University of York study says the alphabet was prepared only after exhaustive tests by several nations, and that changing one word means reconsidering the whole alphabet. University of York ↗
THE RAF
The RAF’s alphabets were different from those used by other British forces. University of York ↗
Before NATO: one alphabet for everyone
THE NAME
The “Able Baker” alphabet was named after its first two code words. NATO ↗
THE COMPLAINT
A common criticism of the earlier alphabets was that they leaned too heavily on English. NATO ↗
TWO ALPHABETS AT ONCE
Even after IATA’s alphabet was adopted for civil flying, the armed forces and NATO kept using Able Baker for several years. NATO ↗
Civil and military authorities finally agreed there should be one universal phonetic alphabet. NATO ↗
A SHORT, ODD PAUSE
For a short while NATO’s military commands were the only users of the new alphabet, as allied forces waited for ICAO to decide. NATO ↗
ICAO’S FIRST TRY
ICAO was set up in 1944, and in 1946 it agreed on an international alphabet: the Combined Services Alphabet. University of York ↗
THE WAR YEARS
ICAO’s paper says a new era of international alphabets began when the United States entered the Second World War. University of York ↗
Wartime tests found that many words in the military lists were hard to make out. University of York ↗
The York study says that during the war, the generals and admirals settled the list by taking first a US and then a UK preference, “to complete the list and get on with the war”. University of York ↗
How the words were chosen and tested
Much of what we know about the testing comes from ICAO and NATO papers of the 1950s, quoted in Alistair Edwards’s study at the University of York. The 1959 ICAO report was released under a Freedom of Information request in 2011. University of York ↗
203 ALPHABETS
A 1959 ICAO report, quoted in the University of York study, counted no fewer than 203 different spelling alphabets. University of York ↗
That 1959 ICAO paper dates the first ITU alphabet to 1926; NATO’s own history page gives 1927. University of York ↗
WHY THE CITIES WENT
ICAO later judged the ITU city-name words unsuitable, because they were unusual in everyday language and lacked useful sound qualities. University of York ↗
SPEECH IN NOISE
According to the York study, ICAO’s alphabet was developed using experiments with recordings of speech in noise, to measure how clear and how easily confused each word was. University of York ↗
In noise, the vowels, especially stressed vowels, and the rhythm of a word become the most important clues for recognising it. University of York ↗
THE LISTENING TESTS
The new alphabet was tested for English, French and Spanish, the three main languages of NATO’s member countries at the time. University of York ↗
In the tests, speakers from the NATO nations read out lists of random three-letter groups. University of York ↗
Listeners had about twelve hours of listening practice before the tests. University of York ↗
The test lists were heard under three set levels of background noise. University of York ↗
OUT: COCA, METRO, EXTRA
After the tests it was decided to replace Coca, Metro and eXtra with Charlie, Mike and X-ray. University of York ↗
In ICAO test figures reproduced by the York study, Metro had an articulation score of 52.9%, against a mean of 77.8%. University of York ↗
NECTAR TO NOVEMBER
British researchers noted that Nectar and Victor sounded alike. University of York ↗
In the York study’s analysis, Nectar was one of the weakest letters, while its replacement, November, is the strongest. University of York ↗
The York study’s tables show a test version that swapped Foxtrot for Football and Zulu for Zebra; the final version brought back Foxtrot and Zulu and added November. University of York ↗
THE DENT IN THE BALL
An ICAO paper of 1955 compared changing the alphabet to pushing a dent out of a child’s celluloid ball: fix one spot and another pops out. University of York ↗
THE RULES FOR A GOOD WORD
The words were chosen to start with the letter they stand for. University of York ↗
The code words also must not sound like other standard radio words, such as Roger, Over and Negative, or Mayday. University of York ↗
Another rule: no word should suggest a rude meaning in any common language. University of York ↗
GOLF AND X-RAY
Golf works well because if the G is missed, no other code word ends in “olf”. University of York ↗
Very few English words start with X, which is why many alphabets use X-ray. University of York ↗
Xanthippe, the ITU’s word for X in 1932, was the name of the wife of Socrates. University of York ↗
ONE E OR NONE
The spelling Whiskey follows the American and Irish style; a Scot drinks Whisky. University of York ↗
WHY NOT JUST SAY THE LETTERS?
Ordinary letter names are easy to confuse: the York study found 40 pairs that differ by just one sound. University of York ↗
English is the official language of radio communication, the York study notes. University of York ↗
HERE TO STAY
The York study thinks the alphabet is most unlikely ever to be replaced, simply through inertia. University of York ↗
Why NINER, TREE and FIFE?
The official manuals we checked (the ITU, ICAO via the FAA and UK CAA, the IMO and ACP 125(G)) set out these pronunciations but don’t explain them. The best explanation we found is an analysis in the University of York study, and the NATO paper it quotes.
NINER
The York study’s own analysis found the “-er” added to Nine works: plain “nine” differs from “five” by only two sounds. University of York ↗
TREE
The same analysis flags Two and Tree (Three) as a worry, as they differ by only one sound. University of York ↗
ZERO AND SIERRA
A NATO paper of 1955 noted that Zero and Sierra sound quite similar, and suggested saying the word “Figures” before numbers. University of York ↗
THE FORGOTTEN NUMBERS
Many research papers on spelling alphabets, including ICAO’s 1959 report, don’t discuss the numbers at all. University of York ↗
The word “zero” was first recorded in English in 1598, according to the Oxford English Dictionary (as quoted by the York study). University of York ↗
Flags at sea: the International Code of Signals
1855–57
The first International Code of Signals was drafted in 1855 by a committee set up by the British Board of Trade. International Code of Signals (Pub. 102) ↗
It held 70,000 signals using eighteen flags, and was published in 1857. International Code of Signals (Pub. 102) ↗
1897 AND THE FIRST WORLD WAR
A revised code was completed in 1897. International Code of Signals (Pub. 102) ↗
The code did not stand the test of the First World War. International Code of Signals (Pub. 102) ↗
1927–32
A conference in Washington in 1927 led to a code in seven languages: English, French, Italian, German, Japanese, Spanish and Norwegian. International Code of Signals (Pub. 102) ↗
That code was adopted by the International Radiotelegraph Conference in Madrid in 1932. International Code of Signals (Pub. 102) ↗
1965–69
Today’s code was adopted by the Fourth Assembly of IMCO (now the IMO) in 1965. International Code of Signals (Pub. 102) ↗
It was prepared in nine languages: the original seven plus Russian and Greek. International Code of Signals (Pub. 102) ↗
The current code came into effect on 1 April 1969. International Code of Signals (Pub. 102) ↗
Dates and lists come from NATO’s own history page, the University of York study and the International Code of Signals. See all sources.