Abstract : In most domains involving expert knowledge, there is a number of cognitive and social factors influencing how efficient one human being is at correctly assessing and responding to certain situations. These factors, which contribute to the efficient and safe realization of a technical activity, are known as non-technical skills, and correspond to a wide range of cognitive proficiencies such as situation awareness, decision making, stress or fatigue management, but also social skills such as communication, leadership and team working. Different studies have shown the impact such skills can have in the successful resolving of a number of critical situations, even more so in our domains of interest which are medical surgery or driving. In this paper, we take a look at the difficulties raised by the teaching of the technical and non-technical skills mobilized during a critical situation, in the context of TEL within virtual environments. We present the advantages of using a combined enactive and situated learning approach to this problematic, and then take an ill-defined perspective to raise some important designing issues in this respect. We show that some aspects of this problem have not been encompassed yet in the ill-defined domains literature, and should be further studied in any attempt at teaching behaviours inducing technical and non-technical skills in a virtual world.