Amother time at Gatwick, using politeness and good manners, I was let onto a Lear Jet and sat in the pilots seat! That was awesome for a 14 year old!
Sad to say in these days of (rightly) enhanced security this is unlikely to be the norm...
Two years ago my daughter sat in a 757's P1 seat when she was 15.95 years old.
So, it isn't impossible, fortunately.