Abstract: Command and Control systems (C2) need to be highly usable to efficiently support communication during crisis situations. Short-term usability evaluations are typically carried out because of the cost and time advantage. However, even the most realistic evaluations (simulations) do not reflect the real issues encountered “in the wild”, such as the operators' stress or the multiple foci of attention. In this paper we carry out an experiment to measure the changes in usability of a C2 system between a short-term simulation and a long-term “in the wild” evaluation. We demonstrate that short-term usability measurements can differ significantly from long-term “in the wild” ones. Our results indicate that a different approach to usability assessment is needed when dealing with critical systems, that takes into account the temporal horizon and assesses the system in real-life conditions.