Quantitative relationship model between workload and time pressure under different flight operation tasks

• Measurement parameters effectiveness was tested under different time pressures and tasks.
• The workload “redline” was defined with the comprehensive consideration.
• Relationship models between workload parameters to time pressure were established.

The goal of this study was to establish a quantitative relationship model between workload and task demand under different tasks, when time pressure was set as the main influential factor to the task demand, with three workload measurement parameters. The workload “redline” was also analyzed and determined with the relationship models between the workload measurement parameters and time pressure. The experiment was designed with three different tasks under different time pressures. Three workload measurement parameters (subjective evaluation workload, accuracy and pupil diameter) and the subjective feeling threshold of time pressure were measured experimentally and then used in a comprehensive analysis for the relationship model. The data analysis result showed significant differences in workload under different time pressures, but workload was not affected by the task type. With a time pressure of 0.8, participants felt a sense of time urgency and the accuracy decreased by approximately 85%. The results demonstrate that the subjective evaluation workload, accuracy and pupil diameter can be used as the measurement parameters for the workload under different time pressures and for different tasks. Thus, for a time pressure of 0.8, an accuracy of 80%–85% was determined as the workload “redline”. Linear relationships were found between subjective evaluation workload, and pupil diameter and time pressure, and a quadratic curve relationship was found between accuracy and time pressure. Workload prediction can thus be performed using these relationship models between workload and time pressure.