Designing human-machine interfaces (HMIs) for defence systems (such as vehicle-based weapon terminals) faces numerous challenges such as limited workspace, operation in extreme environments and essential protective gear for operators and equipment. This paper presents a study designed to investigate the HMI and teaming for ground-based air defence systems and reports the findings. The objective of the first stage of the study is to assess the usability, satisfaction, ease of use and design of the current systems to identify avenues for improvement in future system development. The main findings confirm some of the issues identified in the early human factors analysis, such as the lack of space, task complexity and the level of expertise required for efficient system operation. The reported findings do not just help identify the areas for improvement in the HMI, but also identify tasks that could be assisted by Artificial Intelligence (AI) integrated within current system functions, to improve human performance whilst also reducing cognitive load, errors and the risk of poor decision-making.