My first flight truly alone was DFW-LBB in 1991 and I was 19 and on my way to transfer orientation at Texas Tech. I had a friend who had just started working in special services for AA and I got upgraded by him. (Same friend still works for AA today and I still bump into him at DFW.) I also made several new friends on the flight who remained friends at Tech and some of whom I still talk to today.

I had flown sans parents many times prior to this - but I was always with a friend or someone else I knew, including a flight on Aeroflot. So getting on a plane totally alone was not a big deal at all to me when I finally did take a flight where I didn't have a companion. (I won't go so far as to say "didn't know anyone... as even when I was taking "solo" flights in college and after, I almost always ran into someone I knew on the plane.)