Task: Explanation
Input (English): Joe Henry Engle (born August 26, 1932), (Maj Gen, USAF, Ret.), is an American pilot who served in the United States Air Force, test pilot for the North American X-15 program, aeronautical engineer, and a former NASA astronaut. As of 2017, he is the last living pilot of the X-15 program. Question: NASA Astronaut Group 5 includes the last living pilot of which North American test flight program? Answer: X-15
Output (English):  As of 2017, he is the last living pilot of the X15 program.