In this study, we will compare the safety and effectiveness of ketamine and propofol in sedating acute psychiatric patients needing aeromedical retrieval. We believe that this is the first trial of its kind which will elucidate the complications, the safety profile and effectiveness of the two drugs in sedating acute psychiatric patients. The study will be a prospective, open-labelled, randomised controlled trial. Patients will be drawn the Northern Territory and Queensland. Through this study, we will better inform clinicians in their choice of a suitable sedation agent and potential provide an additional sedation choice in aeromedical and other critical care environments. Furthermore, this research has the potential to establish sedation guidelines in the aeromedical retrieval of acute psychiatric patients for Australia and internationally.