Three F-35A Lightnings from the 63rd Fighter Squadron at Luke AFB, Ariz., fly in formation while one takes on fuel from a KC-135 Stratotanker over Arizona in August. F-35s are the newest combat aircraft in the Air Force inventory, while the KC-135s date back to the 1960s, and are approaching an average age of 59. With the new KC-46 still years from being deployment ready, those old Stratotankers will still be around a while longer.