Innovation Concept: Effective communication for ad hoc teams is critical to successful management of multisystem trauma patients, to improve situational awareness and to mitigate risk of error. OBJECTIVES 1. Improve communication of ad hoc teams. 2. Identify system gaps. INNOVATION Team in situ simulations provide a unique opportunity to practice communication and assess systems in the real environment. Our trauma team consists of residents and staff from emergency services, general surgery, orthopedics, anaesthesia, nursing and respiratory therapy. Methods: A team of subject matter experts (SME's) from trauma, nursing, emergency medicine and simulation co-developed curriculum in response to a needs assessment that identified gaps in systems and team communication. The simulation occurred in the actual trauma bay. The on-call trauma team was paged and expected to manage a simulated multisystem trauma patient. Once the team arrived, they participated in a briefing, manikin-based simulation and a communication and system focused debriefing. Curriculum, Tool, or Material: Monthly scenarios consisted of management of a blunt trauma patient, emergency airway and massive hemorrhage protocol. Teams were assessed on communication skills and timeliness of interventions. Debriefing consisted of identification of system gaps and latent safety threats. Feedback was given by each discipline followed by SME's. Information was gathered from participant evaluations (5-point Likert scale and open ended questions) and group debrief. Feedback was themed and actions taken to co-create interventions to communication gaps and latent safety threats. As a result, cricothyroidotomy trays were standardized throughout the hospital to mitigate confusion, time delay and unfamiliarity during difficult airway interventions. Participants felt the exercise was an effective means of practicing interprofessional communication and role clarity, and improved their attitude towards the same. Conclusion: In situ simulation-based education with ad hoc trauma teams can improve interprofessional communication and identify latent safety threats for the management of multisystem trauma patients.