Concepts for intuitive and multimodal display interfaces were investigated for some operator environments and tasks. Performed foremost in simulators, studies and experiments involved applications primarily related to Combat Vehicle 90 and military aviation. The evaluations of the display interfaces have shown that they can improve operator or pilot performance. With the proper allocation of presented information over sense modalities, operator performance can be made more efficient. With redundant presentation to several sense modalities, important and prioritized information can be enhanced so that operator responses are improved.