In the best of all possible worlds, the ground staff will watch your kid closely to make sure he gets on the flight, makes the right connection, and that the right person is there to meet him on the other end. But airports are crowded, confusing places. Heck, I often see adults wandering around terminals totally befuddled. And I have heard horror stories of kids who have gotten lost in the shuffle, stranded in an unfamiliar airport when their connection was canceled or delayed. In a strange place, perhaps incapable of making a long distance call, a child can panic.
Bad things can happen.
If you need your child to fly alone, try to get a non-stop flight, or at least a direct flight that may stop but doesn't require a change of airplanes. Don't leave the gate until your child is on board and the door of the plane is closed. And make sure you have a plan if the person who's supposed to meet your child on the other end isn't there when the plane lands. If your summer travel plans include foreign countries, keep a couple of things in mind. The problem of non-custodial parents abducting children and taking them abroad is on the rise.