Before the 1950s, there was no standardized form of communication around the globe. Each country had its own rules and phonetic alphabets for air traffic communications. The difference in the phonetic alphabet used may have caused confusion or ambiguity over the radio. The International Civil Aviation Organization (ICAO) started the process of coming up with a standard alphabet system for the whole world in 1948, where they collaborated with linguistics professor Jean-Paul Vinay. The words had to comply with the following conditions:
Be an existing and valid word in the English, French or Spanish languages
Have good radio transmission and be easily pronounced and recognized in all three languages
Must not have a negative meaning
However, the first versions were deemed ineffective in communicating letters and numbers as the use of some words was proven confusing in extended communication. After many comprehension tests and the involvement of more than 70 nationalities, in 1956, ICAO approved the final version of the worldwide phonetic alphabet we use today.