When he was 14 my son travelled as an UM a number of times.
"Where were the parents?", someone asked, tut, tut.
Over 6,000 miles away! After his first flight, where he was allocated a member of staff to look after him, he specifically asked not to be "nannied" over again as he found it very embarrassing. He was perfectly capable of getting himself from boarding school in Lincolnshire to LHR and onto the flight. We spoke to the airline in this respect and subsequently wrote a letter waiver to them, which was accepted.
He came to no harm. But by that age he was nearly 6ft tall and was an athletically built rugby player; he towered over the CC and many other pax.