The Trinity National Historic site opens two weekends a year and I’m going to its April open weekend. I thought to drive at first but a plane proved cheaper so I started looking for fares. Repeated search yielded no results and I was mystified as I had previously flown from Tucson to Philadelphia and back and a little sleuthing exposed my error: I had entered TUC instead of TUS and PHI instead of PHL. Apparently, there are no flights between Benj Matienzo Airport in Argentina and Pinheiro Airport in Brazil. Good to know.