Why do Canadian airports start with yy?

The Curious Case of the Canadian "Y" Airports: Why So Many Start with Y?

Have you ever noticed while booking a flight to Canada that many airport codes seem to start with the letter "Y"? YYZ (Toronto Pearson), YVR (Vancouver International), YYC (Calgary International) – the list goes on. This isn't a coincidence, and the reason behind it delves into the early days of Canadian aviation and a simple "yes" or "no" question.

Before the International Air Transport Association (IATA) standardized airport codes with its three-letter system, Canada had its own, simpler method. This earlier system used two-letter identifiers for weather stations, many of which were located near or at burgeoning airfields. Crucially, these identifiers often began with a "Y" or a "W".

The "Y" signified "yes" to a key question: Did the weather station have a radio transmitter? This seemingly straightforward question was vital in the early days of flight, where reliable weather information was essential for safe navigation. A "W" meanwhile, meant the station didn't have a radio transmitter ("W" possibly for "without"). As airfields grew and became more established, these existing weather station codes were conveniently adopted as airport identifiers.

With the global expansion of air travel and the adoption of the IATA's three-letter system, Canada faced a small problem. While the existing two-letter codes could easily be expanded by adding another letter (often a "Z" for locations further from the original weather station or to differentiate between multiple airports in a city), the limited number of "Y" combinations started to become insufficient.

To accommodate the growing number of airports, Canadian authorities began assigning "Z" as the first letter for newer airports. Examples include YZF for Yellowknife and YZS for Samson Cree Nation. While the original "Y" significance tied to radio transmitters is no longer relevant in the modern era of sophisticated communication systems, the legacy persists, making the "Y" and increasingly the "Z" a distinctive characteristic of Canadian airport codes. So next time you see a "Y" or a "Z" at the start of an airport code, you'll know it points to a Canadian destination and a little piece of aviation history.