The Trinity National Historic site opens two weekends a year and I’m going to its April open weekend. Â I thought to drive at first but a plane proved cheaper so I started looking for fares. Â 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. Â Apparently, there are no flights betweenÂ Benj MatienzoÂ Airport in Argentina andÂ Pinheiro Airport in Brazil. Â Good to know.