Pilot incapacitation can occur among all age groups. It can be obvious or subtle; temporary or permanent; and partial or complete. Its origin can be physiological or psychological or both. Its inherent risk to aviation safety can be virtually eliminated in a multi-crew operation. Control of the operational consequences of pilot incapacitation is both a traditional aeromedical problem and a training problem. Despite very considerable progress, the importance of its training aspects are not always recognized. Controlling “cognitive” incapacitation is the newest challenge.