Aviation medical standards world-wide place much emphasis upon the cardiovascular (CV) status of the individual. This is justified, especially in the Western world, because of the high incidence of CV disorders in the population and their likely similar occurrence in the aircrew peer group. These standards do not in general require the demonstration of any objective short fall in performance, but rather guard against a potential threat, that of sudden incapacitation. However, some observers have sought to question whether or not this threat and its potential consequences is as great as it might appear and to quantify the risks. We have now carried out and analysed over 1,300 closely observed simulator exercises, using two protocols, in which sudden and subtle incapacitation has been programmed to occur to the handling pilot at a critical phase of flight. The results have been assembled and extrapolated with the recorded incidence of sudden incapacitation in flight in civil airline operations so the actual degree of risk can be identified. Conclusions can be drawn from this on the relevance of present cardiovascular standards and suggestions for improvement are made.