Why Do Canadian Airport Codes Begin With The Letter Y?

Do you know the reason whY?

Anyone who's flown knows that every airport has a unique three-letter code associated with it. You'll see these IATA codes everywhere, from tickets to barcoded luggage tags to boarding passes. A good portion of the world's airports have codes that make sense in relation to their respective city or historical name. So why do Canadian airport codes begin with the letter Y? Let's find out.

YVR (Vancouver), YYC (Calgary), YYZ (Toronto), YUL (Montreal) - all of these codes obviously begin with the letter Y. But before we get to the explanation, let's see what most other airports are doing.

Canadians: the odd ones out?

It really does seem like Canadian airports are unique in this respect. There doesn't appear to be any other country in the world with a first-letter theme for its IATA codes. Many airports simply use a combination of letters that generally make sense with the city that an airport serves. Here are just a few examples:

LHR and LGW: London Heathrow and London Gatwick
TPE: Taoyuan International Airport serves the city of Taipei (Taiwan)
NRT and HND: The two airports of Narita and Haneda both serve the Tokyo Metropolitan Area in Japan
DAR: Julius Nyerere International Airport serves the Tanzanian city of Dar es Salaam
KWI: Kuwait International Airport
BOG: El Dorado International Airport serves the city of Bogota (Colombia)

Sometimes airport codes are more associated with the airport's name itself and aren't tied to the name of the cities they serve. For example:

CDG: Paris Charles de Gaulle
JFK: New York's John F. Kennedy
SVO: Moscow's Sheremetyevo International Airport

From two letters to three

According to the Globe and Mail, and its reference to an article by the Air Line Pilots Association, airlines originally copied a two-letter system used by the US National Weather Service to identify cities around the United States.

However, aviation services were growing fast in the 1930s, and towns without weather-station codes needed identification. Perhaps realizing the limits of a two-letter code, which provided only 676 combinations, it was decided that a three-letter system should be implemented. This would, in turn, provide a much more robust selection of 17,576 possible combinations.

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Then, to ease the transition for existing two-letter-airports, some would use an X after the weather-station code. Thus, the code for Los Angeles' airport became LAX.

So 'Y' Canada?

According to Airfarewatchdog, in the 1930s, it was important to know whether or not an airport had a weather/radio station located on its premises for safety and landing reasons. If it did, the letter Y for "yes" was added in front of the existing radio call sign. However, in the absence of a weather station at the airport, a W would be used to symbolize that it was "without" one.

Thus, when the three-letter system was imposed during the 1940s, most of Canada's airports had already been using the Y for "yes" prefix due to weather/radio stations located on-site. It was then decided that this should remain in place for the overwhelming majority of Canada's airports (some begin with the letter Z).

While Canada has most of the world's airport codes beginning with the letter Y, a few outside the country also start with the same letter. Among these are Yakima, Washington (YKM) and Yuma, Arizona (YUM).

What about ICAO codes in the US?

As established, airports in the US generally have three-letter IATA codes that correspond more directly to their locations. However, when it comes to their four-letter ICAO designations, they also all tend to start with the same letter, namely K. There are certain exceptions, with these being found in the states of Alaska and Hawaii. Here, airports' ICAO codes start with PA and PH respectively.