All operations

Spelling alphabet

Alfa, Bravo, Charlie. For reading characters down a bad line.

What it does

Each letter becomes a word chosen so that no two can be confused when spoken. B and V sound alike over a poor connection; Bravo and Victor do not.

Where it came from

The set in use today was settled by ICAO in 1956 and adopted by NATO the same year, after comprehension tests across speakers of thirty-one nationalities. Earlier alphabets were built around what sounded clear to English speakers only, and words that worked in London turned out to fail in Paris or Rome.

The digits get their own treatment in aviation and maritime use, where “nine” is spoken as “niner” to keep it distinct from the German “nein”.

What it is for

Reading a reference number, a license plate, a postcode or a serial number to another person out loud without either of you having to guess.

For a key fingerprint, forty words for twenty bytes gets unwieldy fast. The PGP word list exists for exactly that case, encoding a whole byte per word instead of a single character.

Morse code solves the same problem for a channel that carries no voice at all.