Im not sure if there is a minimum age but my sister traveled on a plane by her self when she was 12.

check with the airline. There are various ways of travelling alone - one is when you are totally alone - some european airlines require you to be 14 for that. But there is also an "unaccompanied minor" scheme - where you effectively travel alone, but you are handed over at the airport by one set of adults, into the care of the airline, who accompany you to the other end where an adult must be waiting for you. I did that for the first time when I was 6 years old!

Check the airline. Some allow as young as 5 without an adult. It also depends on how many stops the plane makes. More stops = more chances of getting off and lost.

I don't think there's a minimum age but I do believe that you need to call the airline ahead of time and let them know so they can make certain special arragements to escort the child since you will probably be required to see the child off at the boarding gate

each airline differs. I just googled 'airlines unaccompanied minor" and many of the airlines have their rules posted. Here is the policy for Southwest: Unaccompanied Minors These policies apply on Southwest Airlines only. Other airlines (including codeshare partners) may have different policies and procedures. For more information on Southwest Airlines policies regarding Unaccompanied Minors, please see Policies, Frequently Asked Questions, and Tips for Children Traveling Alone. Children age five through 11 may travel unaccompanied on Southwest Airlines as long as they have a confirmed reservation on a nonstop or direct flight (makes a stop but does not require change of planes or flight number). Proof of age may be required. Effective for reservations purchased or changed on or after June 1, 2009, for travel on or after June 17, 2009, Southwest Airlines will collect a $25 one-way service charge for children traveling as Unaccompanied Minors. Southwest Airlines will not transport Unaccompanied Minors on flights we think might be cancelled or diverted due to weather or other operational situations. When making reservations, please advise the Customer Representative at 1-800 I FLY SWA that the booking is for an “Unaccompanied Minor”. Southwest Airlines asks that you have the Unaccompanied Minor check in at the Departure Gate at least 45 minutes prior to departure. An Unaccompanied Minor form must be completed and the $25 one-way service charge must be collected before Southwest Airlines can accept the child for travel. View Unaccompanied Minor form in PDF format. The Unaccompanied Minor form will be inserted in the Unaccompanied Minor lanyard. The lanyard must be worn by the child throughout the entire flight and is needed for Southwest Airlines Employees to identify Unaccompanied Minors. The child will preboard and be introduced to the Flight Attendant as an Unaccompanied Minor. Unaccompanied Minors arriving too late to preboard will be boarded last or between boarding groups to ensure proper introduction and identification to the Flight Attendant. When the flight arrives at its final destination, the unaccompanied child will be escorted off the aircraft by a uniformed Southwest Airlines Employee and released to the person designated on the Unaccompanied Minor form or another designated Southwest Airlines Employee. The receiving party should follow the Suggested Airport Arrival Times in order to allow time to obtain an “escort pass,” which grants access through security checkpoint to meet the child at the aircraft’s Gate. A federally-sponsored identity verification process at the ticket counter is required before issuing an “escort pass.” The party picking up the child must be the person designated on the Unaccompanied Minor form, which is completed at the beginning city of the journey. Southwest Airlines will require the designated receiving party to produce positive identification and sign a release for the Unaccompanied Minor. In some cases, there may be a brief wait in receiving the child while Southwest Airlines personnel are engaged in the release of other unaccompanied children or the departure of another aircraft. We hope you will understand that the time spent is for the safety of your unaccompanied child.