When a pilot is communicating with air traffic control, static and other interferences would often create confusion with specific English language letters. In the very early days of civil aviation and military communication, and even today when dealing with businesses over the phone, a universal spelling alphabet is used to clarify parts of messages that contain letters and numbers.
This is known as the International Radiotelephony Spelling Alphabet (also referred to as the ICAO Phonetic Alphabet and the NATO Alphabet) – the use of it was formally adopted by ICAO on 1 November 1951, as a universal standard for communicating English letters over a phone or radio.
Dissatisfaction with the existing internationally recognized phonetic alphabet submitted to ICAO for consideration, led to a first draft of a proposed single universal alphabet. Through 1948 and 1949, in collaboration with ICAO’s language section, Professor Jean-Paul Vinay of the Université de Montréal in Canada, worked to improve it. After those studies and following consultations with communications experts and comments from all of ICAO Member States, on 1 November 1951, a new ICAO alphabet was adopted and incorporated in the Aeronautical Telecommunications Annex 10 for implementation in civil aviation. The words that represented the letters C, M, N, U and X were replaced, and the final version in the table below was implemented by ICAO on 1 March 1956, and is still in use today around the world.
How many letters do you know?
You can find out more about the development and implementation of this alphabet at the ICAO Museum, which is situated inside ICAO’s Montréal Headquarters.