The USA and Japan don't follow the rest of the world, the callsign isn't N-(four letters) or J- four letters. it's just N or J, no dash, letters and numbers. At the White Waltham Bash I saw a light aircraft with an N-reg, it must have flown US-Goose-Gander - Nuuk -Keflavik-some place in Scotland. I understand ferry pilots do this route routinely. As I only fly hang-gliders, and not over water, this seems slightly awesome to me.