Background The nurse-in-charge (NIC) role has been implemented in many emergency departments (EDs) to assist with smooth operations and coordination across the ED, together with the emergency physician in charge (EPIC). This work aims to describe the problem-solving approaches used by NICs and the coordination of their role with other team members. Methods Observations and semi-structured interviews were performed with NICs in a single centre, where NICs were purposively sampled for a variety of experience levels. During the observations, field notes were taken for every action conducted by the NIC in ED; the semi-structured interviews involved a combination of question prompts and a blank diagram of the ED that the NICs were asked to annotate. Constant comparative analysis based on grounded theory methodology was used for this qualitative study.  Results Eight different problem-solving approaches were identified. These are placing, targeting, guiding, juggling, chasing, team-leading, escalating and de-escalating. The last three were exclusive to NICs, whereas the others were shared to some degree with the EPIC. Seven team situational awareness processes used by NICs for coordination with other team members were identified, leading to a discussion on team synchronisation and shared awareness mechanisms. In particular, shared internal models amongst the NICs and also other team members provide a framework for analysing how team members function together in a healthcare setting.  Conclusions Emergency department NICs have a number of problem-solving approaches that have been defined and shown to have a degree of overlap with the emergency physician in charge. Shared awareness between the NIC and other ED team members facilitate decision-making and smooth coordination. These findings provide a better understanding of the role of the NIC and are useful for describing solutions for patient flow.