B-52 Stratofortress. They started making BUFs 49 years ago. The youngest one is 38 years old. Most airframes are designed to last twenty years. The years have whittled down the original 744 aircraft to 76, but they intend to fly these jets for decades to come. Already, one pilot has flown the same B-52 his dad flew. That was 15 or 20 years ago. Within the next few years it is theoretically possible for an Air Force pilot to fly the same bomber his grandfather flew.