Urgency-Based color coding to support visual search in displays for supervisory control of multiple unmanned aircraft systems

•This study proposes an urgency-based color coding concept of system states in icon-based displays for supervisory control of multiple unmanned aircraft systems.•A numerical measure (TS = Target Salience) was developed that is used to quantify the visual target salience based on differences in color space between target, distractor and background. It is computed by dividing the color difference between target and distractor by the color difference between distractor and background and multiplying the result by the division of the target-distractor and distractor-background color differences. The target salience value increases when decreasing the difference between distractor and background color as well as increasing differences between target and distractor and target and background colors.•The developed target salience measure TS is used to determine the colors used to represent system states such that the salience of the color corresponds to the urgency of the system state, while supporting parallel search.•The results of the study suggest to use grey for safe indications, yellow for caution indications, red for warnings and cyan for advisory indications. This color coding concept allows for parallel search, while search is faster for caution and warning than for advisory indications.•The results are transferable to the design of icon-based displays in similar domains, such as highly automated ground and maritime transport systems.