An airport with very poor public surface access
When transforming former military airfields in to regional airports that is invariably what one is going to get, p1ss poor transport. Just by the nature of the beast military air bases are often stuck out in the middle of nowhere, after all city folk don't want noisy aeroplanes flying past so unless one is going to build a brand new designer airport from scratch one is invariably stuck with it.
There are of course the odd exception to the rule such as the former RAF Horsham St. Faith which is right on the edge of Norwich.