How old do you have to be to purchase a plane ticket without parental consent?

My friend is almost 17 and she was wondering how old you must be to buy your own plane ticket. I know that once you're 15 you can travel on your own without being an unaccompanied minor. I'm not sure where she is wanting to travel to though. Thanks a million!!!How old do you have to be to purchase a plane ticket without parental consent?With the new airport and airline rules, you must be 18 yrs old with a valid ID to purchase and board a plane.How old do you have to be to purchase a plane ticket without parental consent?I just asked my mom, she is a Flight Attendant for Continental and she thinks it depends on the airline. I have bought a plane ticket 10 years ago when I was in high school when I was 17. I think you can get away with it, especially now with the airliens so desperate.