One-liner: Addresses the impact of changing skills required of fighter, mobility, bomber, and Special Operations Forces pilots on decisions about replacing or extending service lives of trainer aircraft. 450-character abstract: This monograph examines how the skills needed to perform future military missions might affect the capabilities required of new pilot training systems. In the next few years, the Air Force must decide to replace or extend the lives of two of its trainer aircraft. This monograph addresses which skills should be taught in undergraduate flying training, which are so different that they cannot be taught in current training aircraft, and what impact these issues have on decisions to replace or extend the lives of the aircraft.