This chapter focuses on the insights that the Eyjafjallajokull eruption in April 2010 provided for the coordination of scientific input to decision-making across the European aviation industries. Volcanic eruptions are part of a wider class of natural risks, including earthquakes, pandemics, and regional fires etc., that have to be managed collectively. These, in turn, form a sub-set of adverse events that also include man-made catastrophes, such as terrorist attacks, pollution etc. Natural and man-made risks are collectively known as contingency events. They are characterized by relatively low expected probabilities but extremely high potential consequences. The public increasingly expect commercial and regulatory agencies to adopt a precautionary approach to such events. These expectations extend not just from the time before any incident occurs but also under the stress and time pressure of decision-making during a contingency. If we are to meet these expectations, it is important that operational decision-making is informed by accurate scientific information on a wide range of issues. It should not be shaped by ad hoc political pressures, although these will inevitably play a role.