US airports that begin with 'Y'

Maybe this has been asked before, but why is it that when an airport code beginning with ‘Y’ (such as Y47 - New Hudson, Oakland SW or Y65 - Indian River, Calvin Campbell, etc) is entered, the code is changed to CY47 or CY65 and the airport cannot be found? This occurs whether the airport is entered with or without the ‘K’ prefix. I’ve tried it with other airports that start with ‘Y’ and get similar results. Any suggestions?

It’s because most Canadian airports begin with the letter “Y” - YVR (Vancouver), YYC (Calgary), YYZ (Toronto), etc.

FlightAware sees the letter “Y” as the first letter in the code and automatically appends “C” to the code to create the ICAO code (CYVR, CYYC, CYYZ, etc.).