@Jeruba I guess the best way to be sure what happened to @Judi doesn’t happen to you is to use your child’s credit card if he has one, and just make a payment to the credit card for him covering it.
@Judi When I worked in Bloomingdale’s we used to have the problem of kids shopping with their parent’s card, and they would need a note or we would call the parent, but they were teens, easily below the age of 18. Since @Jeruba is the one calling to make the ticket it shouldn’t happen. If he prints the boarding pass either before getting to the airport or at a kiosk, no one will even have looked at how it was paid.
@Jeruba Which reminds me, most airlines allow you to check in online the day before flying and print your boarding pass at home. Depending on the airline it might work differently. You could book his ticket online if you have a log-on for the airline. Or, another option is logging on as him and doing it under his information. Not sure which is better. I book most tickets as the person who has logged on, and then just make a ticket for whomever I am purchasing the ticket for.
I think possibly even if you call to make the reservation he can still check in early and print at home. Have his email address handy so he gets a notification, and then all he will need is his confirmation number to log on and print most likely.