Designers of new automated systems typically conduct human-reliability analyses to account for potential human errors that may contribute to system risk. Inaviation, the National Transportation Safety Board (1994) found that the second most common type of error in accidents was tactical decision errors. Efforts to improve flight safety frequently involve training crews in effective decision-making. One fact that has become apparent in developing such training is that decision-making depends critically on the crew’s perceptions of the risks entailed by various threats in the environment. This paper addresses two issues critical to improving the quality of aviation decision-making. (1) How do crews perceive risks associated with aviation decisions? (2) How does risk perception influence flight crews’ decision-making processes? Research findings that address these questions will be presented, along with implications for improving flight crew decision-making.