Did you know? Pilots say 'Alfa' and 'Juliett' because ICAO designed the alphabet for many languages

The "Alfa, Bravo, Charlie" alphabet heard on air traffic control frequencies was deliberately engineered to work across languages. ICAO's own history of Annex 10 explains that the official spellings "Alfa" and "Juliett" are intentional: Alfa avoids the "ph" that some speakers would not pronounce as "f", and the double "t" in Juliett stops French speakers treating the final letter as silent.

Before it, aviation used several alphabets. ICAO's predecessor adopted a list of place names such as Amsterdam, Baltimore and Casablanca in 1932; after the Second World War ICAO adopted the "Able Baker" alphabet in 1946, while South America and the Caribbean used a separate "Ana Brazil" version because English words were not well recognised there. Having two alphabets caused errors, so ICAO set out to create a single universal one.

Professor Jean-Paul Vinay of the Université de Montréal worked on the problem with ICAO's Language Section in 1948 and 1949. Each word had to exist in English, French and Spanish with similar spelling, be easy to pronounce and recognise by radio, and carry no negative meaning. A first version was adopted on 1 November 1951 and used from 1 April 1952, but tests with speakers from 31 countries found some words were confused. Only five were replaced, Charlie, Mike, November, Uniform and X-ray, and the final alphabet took effect on 1 March 1956.