The domain of ambulance command and control is complex due to dispatchers being required to make potentially hazardous decisions, often based on uncertain data, received from distributed sources in an environment that is extremely dynamic. These complexities were established after observing and interviewing fourteen ambulance command and control dispatchers located in two communications centres in New Zealand. In addition to the identification of complexities, the interviews resulted in the formulation of decision strategies utilised by the dispatchers when working in the communication centres. This research has implications for display design and provides avenues of research regarding how best to display the decision-making data required by ambulance dispatchers to overcome the complexities they encounter.