A spelling alphabet, voice procedure alphabet, radio alphabet, or telephone alphabet is a set of words used to stand for the letters of an alphabet in oral communication.
Contents
- History
- Voice procedure
- ITU Phonetic Alphabet and Figure Code
- International aviation
- NATO
- Law enforcement
- Amateur radio variations
- Latin alphabets
- Other alphabets
- References
Each word in the spelling alphabet typically replaces the name of the letter with which it starts (acrophony). It is used to spell out words when speaking to someone not able to see the speaker, or when the audio channel is not clear. The lack of high frequencies on standard telephones makes it hard to distinguish an 'F' from an 'S' for example. Also, the lack of visual cues during oral communication can cause confusion. For example, lips are closed at the start of saying the letter "B" but open at the beginning of the letter "D" making these otherwise similar-sounding letters more easily discriminated when looking at the speaker. Without these visual cues, such as during announcements of airline gate numbers "B1" and "D1" at an airport, "B" may be confused with "D" by the listener. Spelling out one's name, a password or a ticker symbol over the telephone are other scenarios where a spelling alphabet is useful.
A spelling alphabet is also often called a phonetic alphabet, especially by amateur radio enthusiasts, recreational sailors in the US and Australia, and NATO military organizations. However, this conflicts with the usage of the same phrase in phonetics to mean a notation used for phonetic transcription or phonetic spelling, such as the International Phonetic Alphabet, which is used to indicate the sounds of human speech.
History
Prior to spelling alphabets, the words used to indicate English letters were "a", "bee", "cee", "dee", "e", etc. Their spoken sounds are difficult to discriminate, particularly over a limited-bandwidth and noisy communications channel, hence the use by armed services of unambiguous phonetic alphabets for electrical voice communication (telephone and radio, but not telegraph). Confusion between letters may not be problematical in some circumstances but, particularly in some military contexts, it can have lethal consequences.
British Army signallers began using a partial spelling alphabet in the late 19th century. Recorded in the 1898 "Signalling Instruction" issued by the War Office and followed by the 1904 Signalling Regulations this system differentiated only the letters most frequently misunderstood: Ack (originally "Ak") Beer (or Bar) C D E F G H I J K L eMma N O Pip Q R eSses Toc U Vic W X Y Z. This alphabet was the origin of phrases such as "ack-ack" (A.A. for anti-aircraft), "pip-emma" for pm and Toc H for an ex-servicemen association. It was developed on the Western Front of the First World War. The RAF developed their "Telephony Spelling Alphabet", which was adopted by all three services and civil aviation in the UK from 1921.
It was later formally codified to provide a phonetic equivalent for all 26 letters (see comparative tabulation of military alphabets before 1956).
For civilian users, in particular in the field of finance, terms such as "November" for N and "Kilo" for K were considered too long or obscure, and an alternative alphabet arose. Common first names were a popular choice, and the First Name Alphabet came into common use.
Voice procedure
Spelling alphabets are especially useful when speaking in a noisy environment when clarity and promptness of communication is essential, for example during two-way radio communication between an aircraft pilot and air traffic control, or in military operations. Whereas the names of many letters sound alike, the set of replacement words can be selected to be as distinct from each other as possible, to minimise the likelihood of ambiguity or mistaking one letter for another. For example, if a burst of static cuts off the start of an English-language utterance of the letter J, it may be mistaken for A or K. In the international radiotelephony spelling alphabet known as the ICAO (or NATO) phonetic alphabet, the sequence J-A-K would be pronounced Juliet-Alpha-Kilo. Some voice procedure standards require numbers to be spelled out digit by digit, so some spelling alphabets replace confusable digit names with more distinct alternatives; for example, the NATO alphabet has "niner" for 9 to distinguish it better from 5 and the German word "nein".
ITU Phonetic Alphabet and Figure Code
Defined by various international conventions on radio, including:
For the 1938 and 1947 phonetics, each transmission of figures is preceded and followed by the words "as a number" spoken twice.
The ITU adopted the International Maritime Organization's phonetic spelling alphabet in 1959, and in 1969 specified that it be "for application in the maritime mobile service only".
Pronunciation was not defined prior to 1959. For the 1959–Present phonetics, the underlined syllable of each letter word should be emphasized, and each syllable of the code words for the figures (1969–Present) should be equally emphasized.
International aviation
The ICAO Radiotelephony Alphabet is defined by the International Civil Aviation Organization for international aircraft communications.
NATO
The NATO phonetic alphabet is defined by the North Atlantic Treaty Organization and the five-nation subgroup of its members that maintain the Allied Communications Publications. This spelling alphabet evolved from the procedures of several different Allied nations during World War II, including:
Law enforcement
Defined by the Association of Public-Safety Communications Officials-International.
The APCO first suggested that its Procedure and Signals Committee work out a system for a "standard set of words representing the alphabet should be used by all stations" in its April 1940 newsletter.
Amateur radio variations
Officially the same as used by ICAO, but there are significant variations commonly used by stations participating in HF contests and DX (especially in international HF communications).
Latin alphabets
The following examples are from various languages and time periods.
Note: The "LAPD" alphabet has been adopted by many other Public Safety agencies nationwide by way of the Association of Public‑Safety Communications Officials organization (APCO). See https://www.apcointl.org and LAPD phonetic alphabet.
Other alphabets
The Greek spelling alphabet is a spelling alphabet for the Greek language, i.e. a set of names used in lieu of alphabet letters for the purpose of spelling out words. It is used by the Greek armed and emergency services.
The Russian spelling alphabet is a spelling alphabet for the Russian version of the Cyrillic alphabet.
The PGP word list, the Bubble Babble wordlist used by ssh-keygen, and the S/KEY dictionary, are spelling alphabets for public key fingerprints (or other binary data) – a set of names given to data bytes for the purpose of spelling out binary data in a clear and unambiguous way via a voice channel.
In the film "The Return of the Living Dead" a soldier uses an humorous alternative version, saying "Archimedes, Hotdog, Rhubarb, Niner, Zero, Niner" for "AHR909".