Originally Posted by cur
Uh, you clear US homeland security in YYC (yes, IN Canada) and you obviously clear Canada Customs in YYC.
That doesn't matter the airport you are going to still has to have customs facilities. A few years back AS wanted to go from YVR to Orange County but
the government said no because there was no customs facilities there even
though you preclear in YVR. AS was forced to route the flight through SEA.