NATO phonetic alphabet different from International Phonetic Alphabet
Be a live word in each of the three working languages.
Be easily pronounced and recognized by airmen of all languages.
Have good radio transmission and readability characteristics.
Have a similar spelling in at least English, French, and Spanish, and the initial letter must be the letter the word identifies.
Be free from any association with objectionable meanings."After further study and modification by each approving body, the revised alphabet was adopted on 1 November 1951, to become effective on 1 April 1952 for civil aviation (but it may not have been adopted by any military).Problems were soon found with this list. Some users believed that they were so severe that they reverted to the old "Able Baker" alphabet. Confusion among words like Delta and Extra, and between Nectar and Victor, or the poor intelligibility of other words during poor receiving conditions were the main problems. Later in 1952, ICAO decided to revisit the alphabet and their research. To identify the deficiencies of the new alphabet, testing was conducted among speakers from 31 nations, principally by the governments of the United Kingdom and the United States. In the United States, the research was conducted by the USAF-directed Operational Applications Laboratory (AFCRC, ARDC), to monitor a project with the Research Foundation of Ohio State University. Among the more interesting of the research findings was that "higher noise levels do not create confusion, but do intensify those confusions already inherent between the words in question".By early 1956 the ICAO was nearly complete with this research, and published the new official phonetic alphabet in order to account for discrepancies that might arise in communications as a result of multiple alphabet naming systems coexisting in different places and organizations. NATO was in the process of adopting the ICAO spelling alphabet, and apparently felt enough urgency that it adopted the proposed new alphabet with changes based on NATO's own research, to become effective on 1 January 1956, but quickly issued a new directive on 1 March 1956 adopting the now official ICAO spelling alphabet, which had changed by one word (November) from NATO's earlier request to ICAO to modify a few words based on U.S. Air Force research.
After all of the above study, only the five words representing the letters C, M, N, U, and X were replaced. The ICAO sent a recording of the new Radiotelephony Spelling Alphabet to all member states in November 1955. The final version given in the table above was implemented by the ICAO on 1 March 1956, and the ITU adopted it no later than 1959 when they mandated its usage via their official publication, Radio Regulations. Because the ITU governs all international radio communications, it was also adopted by most radio operators, whether military, civilian, or amateur. It was finally adopted by the IMO in 1965.
During 1947 the ITU adopted the compound Latinate prefix-number words (Nadazero, Unaone, etc.), later adopted by the IMO during 1965.
Nadazero - from Spanish or Portuguese nada + NATO/ICAO zero
Unaone - generic Romance una, from Latin ūna + NATO/ICAO one
Bissotwo - from Latin bis + NATO/ICAO two.  (1959 ITU proposals bis and too)
Terrathree - from Italian terzo + NATO/ICAO three ("tree") (1959 ITU proposals ter and tree)
Kartefour - from French quatre (Latin quartus) + NATO/ICAO four ("fow-er") (1959 ITU proposals quarto and fow-er)
Pantafive - from French penta- + NATO/ICAO five ("fife") (From 1959 ITU proposals penta and fife)
Soxisix - from French soix + NATO/ICAO six (1959 ITU proposals were saxo and six)
Setteseven -  from Italian sette + NATO/ICAO seven (1959 ITU proposals sette and sev-en)
Oktoeight -  generic Romance octo-, from Latin octō  + NATO/ICAO eight (1959 ITU proposals octo and ait)
Novenine - from Italian nove + NATO/ICAO nine ("niner") (1959 ITU proposals were nona and niner)In the official version of the alphabet, two spellings deviate from the English norm: Alfa and Juliett. Alfa is spelled with an f as it is in most European languages because the spelling Alpha may not be pronounced properly by native speakers of some languages – who may not know that ph should be pronounced as f. The spelling Juliett is used rather than Juliet for the benefit of French speakers, because they may otherwise treat a single final t as silent. For similar reasons, Charlie and Uniform have alternative pronunciations where the ch is pronounced "sh" and the u is pronounced "oo". Early on, the NATO alliance changed X-ray to Xray in its version of the alphabet to ensure that it would be pronounced as one word rather than as two, while the global organization ICAO keeps the spelling X-ray.
The alphabet is defined by various international conventions on radio, including: