I built a none functional airport using Japanese concourses and terminals. I am trying to make it functional but not sure if it is possible. Should I start over? Any help to building custom airports?
If the airport is already built, the easiest way to add functional capacity is plopping a terminal or control tower from AC Functional Airports (http://sc4devotion.com/csxlex/lex_filedesc.php?lotGET=1664).
Depending on the host city's commecial sector you may need to plop multiple functionals to build up enough capacity. Demand for air transport does not carry-over from neighbor cities or the region; you only need to build for local needs.