American B-720B engines & wing
A theme that threads its way through various parts of this site is the easy access to aircraft we enjoyed in earlier times, and it's exemplified by this shot. Standing under number 4 engine is a little girl, my kid sister Debbie who was about  six at this time.  I don't recall the specific circumstances -- there may have been a last-minute babysitting assignment that was in conflict with my planned trip to the airport, or more likely I had a notion to be a nice big brother and take her along without a parental "request."   Either way, it's plain that the gate agent who let me out on the ramp was unconcerned.  

The key to being turned loose was to only ask about aircraft that were between flights -- through stops were always hurried and everyone was busy -- they just weren't on the ground long enough to let outside a lad with a camera who was looking to shoot half a roll of film.  Of course maximum politeness and a clean shirt & britches were never overlooked as "can't hurt" factors.  In this example, N7501A, American's first jet, is at rest while operating AA's daily LAX-PHL-LAX turnaround.
Philadelphia, August, 1966