Most commercial airlines and similar transporting carriers have Unaccompanied Minor (UM) Programs in place and it is estimated that as many as 7 million children travel by plane yearly, using these UM-programs in the United States alone.
[1] Children all over the world increasingly have family members living far away, including divorced parents who moved overseas for a career opportunity or to start a new household.
Airline UM-programs are approved by national and international civil aviation regulators and larger air carriers tend to handle the transport of UM's on a daily basis and have trained staff and designated waiting areas at their hubs.
Said policies are believed to be a response to reports of in-flight sexual assault, and subsequently the call from parents for airlines to better safeguard their children while traveling as a UM.
In some cases these companies have the ability to provide in-flight care, making it possible for children who suffer from severe allergies or other medical conditions to safely fly without their immediate caregivers.