Years ago, at 15, I flew from Atlanta to London Gatwick, cleared customs, switched to Heathrow, and flew to Israel to meet family. Alone, and without a cell phone. And since my mother, who was going to meet me a week later in Israel was sick when I left, my parents gave my $2,000 in travelers checks in case they could not make the trip, and I had to buy a ticket to come back alone.

I think that you fifteen year old can get to summer camp without an adult.

My 13 year old flew to and from camp in Boston this summer but the camp was at the airport to pick him up (and they dropped him off). He accompanied me on a trip to San Diego a few months ago and I sent him back a few days before me by himself. He had to switch planes in Vegas and his connecting flight was delayed. I was a bit of a mess with visions of a cancelled Vegas flight and my kid having to deal with that but it worked out fine.