This paper considers a key aspect of the 'risk society' thesis: the belief that we should be able to manage risks and control the world around us. In particular it focuses on the interface between risk and risk events as socially constructed and the insights that 'critical situations' give us into 'the routine and mundane', the otherwise taken for granted assumptions underlying risk regulation. It does this with reference to the events precipitated by the April 2010 volcanic eruption in the Eyjafjallajökull area of Iceland. The resulting cloud of volcanic ash spread across Europe and much of Europe's airspace was closed to civil aviation for six days, with far reaching consequences including huge financial losses for airlines. The social processes of defining and reacting to risk and crisis both reveal and generate dilemmas and challenges in regulation. This paper examines the role of different interest groups in defining risk expectations and thereby redefining the ash crisis as a regulatory crisis.