Hi!
ICAO,FAA and UK CAA use an I ,just like the cab...
Of course, but never mynd, thys here is a purely Brytysh thyng
Let me quote from Wykypedya:
"By the time of
Middle English, /y/ had lost its
roundedness and became identical to I (/iː/ and /ɪ/).
Therefore, many words that originally had I were spelled with Y, and vice-versa."
Here in Germany we have had a big spelling reform about 15 years ago and still a lot of people refuse to write the new way. Britain has had it's reform 500 years ago and still some people...