Just received a e-mail from my cousin, who doesn't have children. She states we will need a car seat for my son 4yrs nearly 5 approx 110cms high. Will a booster seat do? Or will it have to be the whole thing. If I have to take the whole thing how will the airline deal with it. Where do you think I can get the info from here? I phoned my aunt and to tell you the truth she didn't have a clue. Can't borrow one out there as they have asked around and no one has spares! I'm going to do some research but if anyone knows the answer I would appreciate it.