It's a sign of independence. Mom, on the other hand, is feeling a little anxious. She knows, of course, that Amanda is far more likely to encounter trouble changing planes than anything else. And she's already devised a plan to handle that. There is an alternative, however.
Most airlines offer an escort service for children flying alone.
Stays with her until her connecting plane arrives. Makes sure she boards and departs on the correct plane. Escorts for children are one of the ways most airlines try to help parents and kids. The girls have flown sans parents more than a dozen times out to visit their father in Montana. Although they've experienced delayed flights, overall they report good experiences.