International Radio Phonetic Alphabet: NATO Alphabet

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Often called the radio phonetic alphabet, this alphabet is widely used for two way radio communications, and other telecommunications services to convey letters unambiguously where interference and bandwidth limitations often make it difficult to distinguish accurately between different letters.

The limited audio bandwidth available means that it is very easy to confuse similar sounding letters, and accuracy can be very important in many radio communications and general telecommunications situations.

The radio phonetic alphabet or spelling alphabet is a set of words that are used to stand for the letters of an alphabet. The words in the phonetic alphabet are used to represent the name of the letter with which it starts - this is actually called acrophony.

Although it is often called the radio phonetic alphabet, a phonetic alphabet is a term used within linguists to record detailed information about the sounds of human speech.

Therefore when used for radio applications a different term is often needed. The more correct term for the radio phonetic alphabet is the International Radiotelephony Spelling Alphabet.

As the International Radiotelephony Spelling Alphabet is widely called the radio phonetic alphabet, this term will be used here for most of the time.

The radio phonetic alphabet is used internationally and hence it is often called the International Radio or Radiotelephony phonetic alphabet. By having an internationally recognised spelling alphabet, all operators will be attuned to it and there will be fewer instances of misinterpretation.

Need for the radiotelephony spelling alphabet

On any two way radio communication link or for other forms of voice telecommunications, the audio bandwidth is limited and interference and distortion may be present.

The radio phonetic alphabet is used to represent the relevant letters. It has been developed over many years in such a way that the words used provide a minimal risk of being mistaken for another one.

Sounds like 'B' and 'T' for 'S' and 'F' are very similar. Other letters can be difficult to distinguish and this means it is possible for messages to be received incorrectly. Even those which may sound very different could be mistaken if signals are poor and interference levels are high

To overcome this words beginning with the particular letter were used from the very earliest days of radio to identify a particular letter and avoid confusion and misinterpretation.

Adoptions

The phonetic alphabet currently used and the one detailed below is often referred to as the ITU phonetic alphabet.

It has also been adopted by a number of other organisations and therefore may also be known by these names as well.

NATO (North Atlantic Treaty Alliance) has adopted the phonetic alphabet for their radio communications and telecommunications. Accordingly references to the NATO phonetic alphabet may also be seen.

The International Civil Aircraft Organisation, ICAO also uses the international radio phonetic alphabet for radio communications between aircraft and ground as well as many other applications. Accordingly the radio phonetic alphabet may also be known as the ICAO phonetic alphabet.

As the spelling alphabet or phonetic alphabet is used internationally, it is also often called the International Radio Phonetic Alphabet, although NATO alphabet is one of the more widely used notations.

ITU / NATO radio phonetic alphabet

The international radio communications phonetic alphabet, is given in the table below:

* Although the normal spellings in plain speech for "alfa" and "Juliett" are "alpha" and "Juliet"", these particular formats for the spellings of these words have been adopted to simplify the comprehension of these words internationally.

The word "alfa" was used because because if the spelling "alpha" was used, it might not be pronounced correctly by non English or French speakers.

Similarly the spelling for "Juliett" rather than "Juliet" was adopted because a single "t" is left silent in French. The use of "tt" meant that the letter t would be pronounced at the end of the word.

By adopting these measures to ensure that the letters are pronounced correctly, it becomes a truly international phonetic alphabet, and for this reason it was adopted as the NATO phonetic alphabet.

The alphabets used by NATO, ITU, and ICAO are all the same in essence: some small differences exist in the ways the actual pronunciation of the words is described.

As an example of the use of the International Radiotelephony Phonetic Alphabet, a callsign such as G3YWX would be said as Golf three Yankee Whisky X-ray.

In cases like these the use of the radio phonetic alphabet is particularly useful because there are no visual clues and other ways of identifying the letters when an audio channel only is used.

History of the International Radio Phonetic Alphabet

The radio spelling alphabet or radio phonetic alphabet has been developed over many years. For just twenty six letters, a huge amount of research and refinement has been invested to ensure that it enables clear and concise radio communication to be effected.

Even before the First World War, the need for a spelling or phonetic alphabet was recognised to ensure improved accuracy both on radio communications and long distance wired telephony circuits.

Some military spelling alphabets were introduced, but the first non-military alphabet introduced in an international scale was adopted by the CCIR which was the predecessor of today's ITU, in 1927. The use of this phonetic alphabet enabled a much enhanced version to be introduced in 1932.

During the Second World War, there was obviously a real need for accurate voice communications. At this point a variety of nations used their own spelling or phonetic alphabets. The RAF developed their own one and this was later adopted as a Joint Army and Navy one which was introduced around 1941. This can still be heard sometimes on the amateur radio bands to this day.

After the war there were several phonetic alphabets in use for radio communication and the then International Air Transport Association recognised the need for a single one to be used. As a result they presented a draft version of one to be used in 1947. This was modified after some use and adopted in 1951. This proved to be unsatisfactory in use and was modified again in 1956, and soon after this it was adopted by the ITU and referred to as the ITU phonetic alphabet, the NATO phonetic alphabet, or even the radio alphabet.

Phonetic alphabet infographic

To help remember and use the international phonetic of spelling alphabet, I've produced an infographic to help.

Since then the ITU Phonetic Alphabet has been in widespread use for all forms of radio communication from shipping to aeronautical and all forms of radio communications.

  Written by Ian Poole .
  Experienced electronics engineer and author.

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