Two studies were conducted to measure expertise in aeronautical weather-related risk perception using the Cochran-Weiss-Shanteau (CWS) index. In the first study, qualified pilots, student pilots, and geography students were presented with weather-related scenarios, and rated the risk involved in each scenario. There was no relationship between flight experience and the CWS scores. The 3 groups of participants did not significantly differ in their CWS scores, although the qualified pilots were the most discriminating, and the geography students were the most consistent. To decrease reliance on memory, the CWS procedure was modified to involve a blocking task and a second study was carried out with qualified pilots. In contrast to Study 1, there was a relationship between flight experience and the CWS scores, suggesting that the adapted CWS procedure was a more valid measure of expertise in weather-related risk perception than the CWS task used in Study 1. The CWS procedure could be a useful tool in assessing expertise in aeronautical judgment and decision making.