Where everything
comes from.

Every code word, “spoken as” guide, radio number and fact on this site, and in our printables, was copied from one of the sources below and checked against it on 31 October 2026. Things we couldn’t find in these sources were left out.

How we handle spelling and pronunciation

• Code words. We use the spellings in Appendix 14 of the ITU Radio Regulations: Alfa, Juliett, Whiskey, X-ray. The code words are spelt Alfa and Juliett in the ITU table, the FAA’s ICAO table and NATO’s own page. CAP 413’s own table writes A as “Alpha”, while giving the same pronunciation, AL FAH. The IMO table spells J as “Juliet”, with one t, and gives zero as ZEERO.
• “Spoken as” guides. Copied exactly from the ITU table, including the two guides it gives for C and U. In the official letter table, the syllables to stress are underlined; this site can’t show that underlining, so check the source for stress.
• Numbers. Aviation numbers are from the UK CAA’s CAP 413, cross-checked with the FAA’s ICAO table. The figure code is from the ITU; sea numbers from the IMO phrases.
• ICAO. We couldn’t open ICAO’s own pages from our checking computer, so ICAO’s rules are quoted as published by national authorities: the UK CAA’s CAP 413 and the US FAA’s manuals (which use ICAO’s alphabet and pronunciations), alongside the ITU table.
• History and testing. The story of how the words were tested comes from ICAO and NATO papers of the 1950s, as quoted in the University of York study; where it gives a different date from NATO’s own page, we say so.
• Read aloud. The converter’s “Read aloud” button uses your device’s own voice. It isn’t an official recording.

All sources

1. ITU Radio Regulations (Edition of 2020), Volume 2, Appendix 14: Phonetic alphabet and figure code
2. NATO: The NATO phonetic alphabet (NATO history, symbols of NATO)
3. UK Civil Aviation Authority: CAP 413 Radiotelephony Manual, Edition 24
4. US Federal Aviation Administration: Order JO 7110.10, Flight Services, Chapter 12 Section 1 (12-1-5 ICAO Phonetics)
5. IMO Resolution A.918(22): IMO Standard Marine Communication Phrases (adopted 29 November 2001)
6. Alistair D. N. Edwards, University of York: Testing the November Alfa Tango Oscar Spelling Alphabet
7. US Federal Aviation Administration: Aeronautical Information Manual, Chapter 4 Section 2, Radio Communications Phraseology and Techniques
8. US Federal Aviation Administration: Aeronautical Information Manual, Chapter 6 Section 3, Distress and Urgency Procedures
9. US Federal Aviation Administration: Order JO 7110.65, Air Traffic Control, Chapter 2 Section 4, Radio and Interphone Communications
10. US Federal Aviation Administration: Pilot/Controller Glossary, A
11. US Federal Aviation Administration: Pilot/Controller Glossary, M
12. US Federal Aviation Administration: Pilot/Controller Glossary, N
13. US Federal Aviation Administration: Pilot/Controller Glossary, O
14. US Federal Aviation Administration: Pilot/Controller Glossary, P
15. US Federal Aviation Administration: Pilot/Controller Glossary, R
16. US Federal Aviation Administration: Pilot/Controller Glossary, S
17. US Federal Aviation Administration: Pilot/Controller Glossary, W
18. Combined Communications-Electronics Board: ACP 125(G), Communication Instructions: Radiotelephone Procedures (copy hosted by the Civil Air Patrol)
19. US National Geospatial-Intelligence Agency: Pub. 102, International Code of Signals (1969 edition, revised)

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