In Kanana wurden die Codes der Bahnhöfe für Flughäfen übernommen. Hatte der Flghafen eine Wetterstation, erhielt dieser ein vorangestelltes Y für Yes.
When the Canadian government established airports, it used the existing railway codes for them as well. If the airport had a weather station, authorities added a „Y“ to the front of the code, meaning „Yes“ to indicate it had a weather station, or some other letter to indicate it did not. When international codes were created in cooperation with the United States, because „Y“ was seldom used in the US, Canada simply used the weather station codes for its airports, changing the „Y“ to a „Z“ if it conflicted with an airport code already in use. The result is that most major Canadian airport codes start with „Y“ followed by two letters in the city’s name: YOW for Ottawa, YWG for Winnipeg, YYC for Calgary, and YVR for Vancouver.
en.wikipedia.org: IATA Airport Code