Complex systems such as aircraft cockpits, Air Traffic Control consoles or Unmanned Vehicle control stations, operators manage a set of tasks with high temporal dynamics and inducing frequent changes of situation within the same mission. These transitions between contexts (triggered by the addition, removal, interruption or retrieval of a task) may reduce operators' Situation Awareness. In this thesis, we introduce SAMANTA (Situation Awareness Modeling and ANalysis for Transition Amelioration), a model-based and user-centered methodology. Designed for Human Factors experts in charge of future systems' analysis and design, this methodology helps identifying and solving the difficulties caused by such transitions. The transitions analysis process is based on the dual description of operators' activity: the modeling of operators' task is associated with the definition of Situation Awareness requirements for each of their tasks (the tasks' context). The experts base their analysis on the characteristics obtained and provide recommendations for the new interfaces in order to support the foreseen impacts. End-users and Subject Matter Experts are involved at different key stages of the design process supported by this methodology. In order to support the implementation of SAMANTA by the analysts, we developped a specific web-based tool. The methodology has been applied to the design of future Unmanned Aerial Vehicle systems, detailing the analysis of two specific transitions.
