Objective: To investigate the disparity in the specification and physiological demand of a task simulation when developed by two independent panels of experiential experts. Design: Independent groups design. Methods: Two groups of experiential experts from the Royal Australian Air Force (RAAF) worked independently to design, and then complete a simulation of a generic occupational task; the establishment of a security control point. Task duration, oxygen consumption, and cardiac frequency were measured whilst each panel completed the task simulation. Maximal acceptable work duration (MAWD) and the percentage of MAWD (%MAWD) were also calculated. Independent t-tests were used to determine differences (P < 0.05) between the measured variables. Results: No differences were observed in the average oxygen consumption (1.26 ± 0.25 L min−1 and 1.28 ± 0.29 L min−1 respectively; P = 0.84), or cardiac frequency (134 ± 16.4 beats·min−1 and 125 ± 8.5 beats·min−1 respectively; P = 0.12) between Panel 1 and Panel 2. However, there was a significant difference between panels with respect to task duration (Panel 1: 15.5 ± 3.68 min; Panel 2: 34.20 ± 9.60 min; P < 0.01), and the %MAWD (Panel 1: 5.32 ± 3.17%, Panel 2: 12.15 ± 9.40%, P = 0.04). Conclusions: The physiological demand of a task simulation is dependent upon the group of experts consulted to develop the simulation. It is critical that input from a wide representation of experiential experts is considered when developing task simulations to avoid bias towards the perceptions of the experts consulted.