ICAO also assigns 3-letter airline codes (versus the more-familiar 2-letter IATA codes—for example, UAL vs. UA for United Airlines). ICAO also provides telephony designators to aircraft operators worldwide, a one- or two-word designator used on the radio, usually, but not always, similar to the aircraft operator name. For example, the identifier for Japan Airlines International is JAL and the designator is Japan Air, but Aer Lingus is EIN and Shamrock. Thus, a Japan Airlines flight numbered 111 would be written as "JAL111" and pronounced "Japan Air One One One" on the radio, while a similarly numbered Aer Lingus would be written as "EIN111" and pronounced "Shamrock One One One". In the US, FAA practices require the digits of the flight number to be spoken in group format ("Japan Air One Eleven" in the above example) while individual digits are used for the aircraft tail number used for unscheduled civil flights.
