I have been studying a lot of different airport and we all know that some have 4 letter codes starting with Kxxx in the USA and Cxxx in Canada, etc.but then some are like WA56ID09S597S3etc, etc.. do the main codes have anything to do with size or if it is publicly owned vs private?thanksbs

Main ICAO codes are designated in a number of ways, but mostly it's geography which determines it: First letter is invariably the continent or main land mass, second letter is often the country, and the last two letters are regional identifiers which may or may not relate to the locale. Generally speaking, airports with the last two letters being similar to another airport will be geographically close to the other one, for example EGCC (Manchester Ringway) and EGCD (Manchester Woodford) are less than ten miles apart, so they are only one letter apart as far as ICAO codes go. Typically the big capital airports get the most easy to understand and relevant code letters, for example, Heathrow (EGLL) can be broken down into: E (Europe) G (Great Britain) LL (London), whereas the nearby Stansted gets EGSS, the last two letters being more about the name Stansted than the fact that it is also an airport which serves the London area and is not too far from Heathrow.The L you see on many European airport ICAO codes (i.e. not starting with E as you might expect) is an abbreviation for 'Lower Europe' (i.e. below Greenwich), so you can see that LFPG (Paris Charles De Gaulle), makes sense, being L (Lower Europe), F (France) PG (Paris, Gaulle), and LEAM (Almeria Spain) follows suit with L (Lower Europe) E (Espania), AM (Almeria, Mediterranean)An exception to things is North America, where it was originally proposed that airports would have K and W designations similar to east and west radio station identifiers in the US, but that was dropped in favour of using K alone to designate the continental USA, whereas P (Pacific) is used as a prefix for Hawaiian airports. Canada gets its own letter too of course, despite being part of the same North American continent as the USA. Most South American countries get a designator beginning with S (for South American continent), followed by the country's initial, C for Chile, A for Argentina etc, with an exception being Mexico, which gets M.So it all kind of makes sense, but it makes more sense for some countries than other ones, especially the ones which were the premier pioneer aviation countries, since they tended to get the best and most sensible designators when everything was being allocated.Al

HA HA - Canada we made it no sense at all.....CYYZ - TorontoCYVR - VancouverCYUL - MontrealCYYC - CalgaryCYEG - EdmontonCYHZ - HalifaxCYOW - OttawaCYWG - WinnipegCYYJ - VictoriaCYLW - KelownaIn the USA you guys getKJFK - John F KennedyKDFW - Dallas Fort WorthKPHX - PhoenixKMIA - MiamiKBOS - BostonKSLC - Salt Lake CityKSEA - SeattleI guess we like to confuss things in Canada with our flights from CYYZ to CYUL, our Postal Codes, Provinces, Metric System, and our 20 hour clocks :(

HA HA - Canada we made it no sense at all.....CYYZ - TorontoCYVR - VancouverCYUL - MontrealCYYC - CalgaryCYEG - EdmontonCYHZ - HalifaxCYOW - OttawaCYWG - WinnipegCYYJ - VictoriaCYLW - KelownaIn the USA you guys getKJFK - John F KennedyKDFW - Dallas Fort WorthKPHX - PhoenixKMIA - MiamiKBOS - BostonKSLC - Salt Lake CityKSEA - SeattleI guess we like to confuss things in Canada with our flights from CYYZ to CYUL, our Postal Codes, Provinces, Metric System, and our 20 hour clocks :(

Same thing here, down here in Indonesia: WIII - Jakarta/Soekarno-Hatta Int'lWARS - Semarang/Achmad YaniWARJ (formerly WIIJ) - Yogyakarta/Adi Sucipto Int'lWADD - Denpasar/Ngurah Rai Int'l WICC (formerly WIIB) - Bandung/Husein Sastranegara Int'lWARR - Surabaya/Juanda Int'lWAJJ - Jayapura/SentaniWAOO - Banjarmasin/Syamsudin NoorWALL - Balikpapan/Sepinggan Int'lWIPT - Padang/Minangkabau Int'lWIMM - Medan/PoloniaWIOD (formerly WIKD) - Tanjung Pandan/Buluh TumbangWIBB - Pekanbaru/Sultan Syarif Kasim II Int'l WIPK - Pangkal Pinang/Depati AmirW-Denotes the coding for Maritime Southeast Asian airportsI-Defines the airport coding for Western Indonesian Airports A-Denotes most airports in Central to Eastern Indonesia R & Q - denotes some airports in Central to Eastern IndonesiaDave.

I have been studying a lot of different airport and we all know that some have 4 letter codes starting with Kxxx in the USA and Cxxx in Canada, etc.but then some are like WA56ID09S597S3etc, etc.. do the main codes have anything to do with size or if it is publicly owned vs private?thanksbs

The 4-letter codes (Kxxx) are ICAO airport codes. These are used for air traffic control and flight planning. There are also 3-letter IATA codes that you see printed on your luggage tags when you take a flight. As far as I know, you wouldn't need these at a small, private field that didn't have some sort of passenger/frieght operations. I'm sure there are exceptions to this.In the US, the FAA also has separate airport identifiers which also use three or four letters. These are the "WA56", "ID09", etc that you list above. For most large aiports, they are three letters and match the IATA codes. Canada uses a similar system, and the two systems are designed to work together to avoid conflicts. As for the reason why they would use FAA location identifiers rather than assign ICAO codes, I can only speculate that the ICAO probably has some practical limitations based on the number of insignificant (to the rest of the world) airports in the US. I believe the US has close to 15,000 airports, most of which do not interest ICAO member countries.- Martin

An exception to things is North America, where it was originally proposed that airports would have K and W designations similar to east and west radio station identifiers in the US, but that was dropped in favour of using K alone to designate the continental USA, whereas P (Pacific) is used as a prefix for Hawaiian airports. Canada gets its own letter too of course, despite being part of the same North American continent as the USA. Most South American countries get a designator beginning with S (for South American continent), followed by the country's initial, C for Chile, A for Argentina etc, with an exception being Mexico, which gets M.

The initial 'M' airport prefix refers to the Central America region. Geographically speaking , Mexico is part of North America, the second 'M' follows the general ICAO formatas the country designator for Mexico.Regards.Ernie.