With E-TKTing, PTA's are a thing of the past....I dont think they are used anymore...What you can do is have the cardholder present themselves at the airport and have the card swiped..>Then as long as it is an 'in person transaction' there is no problem...
However, if the cardholder is in one country and if the fare requires ticketing to be in another country, that is where the problem lies