Tucson is home to Davis-Monthan Air Force Base, a very large, very old, and still very active air base. Originally called “Tucson Army Air Field, the site was quickly renamed Davis-Monthan Army Air Field, then, when the Air Force was spun off from the Army as an independent military service, the site received the name it carries to this day (source). Davis-Monthan has been, and continues to be a very active air base; as with any highly active military installation, accidents do happen, and airplanes do occasionally fall out of the sky (very occasionally, mind you – the Air Force does not enjoy wasting money or airmen on plane crashes).
One such crash is just a stone’s throw from the Butterfly Trail. A modest hike of 2.6 miles (and 1700 feet of lost elevation) leads to a pleasant little canyon with a stream of cool, clear water. How the aircraft ended up there is anyone’s guess (a popular tale involves a mid-air collision with one plane ending up in New Mexico!), but lodged in the dirt after decades of erosion is the obvious tail section of a small airplane. Other bits of debris are also scattered over the area.