Controlling or supervising critical systems exposes operators to increasingly complex problems to manage and to an ever-growing mass of data. These problems constitute a major challenge for operators, particularly in terms of selecting relevant information, understanding the situation, and making decisions, especially in contexts of high time pressure. The advances made in Artificial Intelligence open new perspectives for assisting operators in these contexts. In this paper, we present the user-centered design approach developed to design an AI-based system whose objective is to assist operators in these contexts. This system is characterized by its genericity; it covers different work situations involving critical systems (airplane, information system, electrical network, railway transport). It aims at supporting operators in real time in piloting or supervision activities.