> Typically, the first one or two letters of the ICAO code indicate the country and the remaining letters identify the airport, as indicated by the adjoining figures. ICAO codes provide geographical context.
https://en.wikipedia.org/wiki/ICAO_airport_code
なるほどなあ
en.wikipedia.orgICAO airport code - Wikipedia
@zundan 日本は基本RJだけど沖縄方面だけROなの歴史的事情が感じられて面白い
@ponapalt 大戦後返還前に制定されたみたいですねー
> The International Civil Aviation Organization was formed in 1947 under the auspices of the United Nations, and it established flight information regions (FIRs) for controlling air traffic and making airport identification simple and clear.
https://en.wikipedia.org/wiki/ICAO_airport_code
en.wikipedia.orgICAO airport code - Wikipedia