This paper aims to deeper study the relations between cognitive control and mental workload. Indeed, cognitive control is a contemporary concept in neuroscience and cognitive ergonomics, that can explain the metacognition carried out by operators in their multitasking activity, as well as the regulations that operators implement to manage their level of mental workload. In this paper, an experiment was conducted, where a main task was presented to participants in different conditions of multitasking and difficulty. The scenario was designed with the aid of the Multi-Attribute Task Battery (MATB-II) microworld, which reproduces basic multitasking that a pilot can carry out in an aircraft. The performance and the neurophysiological responses of twenty participants were recorded, especially by analyzing cardiac activity and oxygenation and deoxygenation of the prefrontal cortex. The findings particularly emphasized a link between the level of task difficulty and the control modes, which is highly significant for the tactical mode. Furthermore, fNIRS signals were significantly related to cognitive control modes. Indeed, the tactical mode was found to be the most efficient one, since it is associated with a satisfying performance and with low mental strain, contrary to the other modes with a worse performance and a higher mental strain. These results about the dynamic of cognitive control and the specific sensitivity of fNIRS to tactical control mode open new perspectives for proposing new ways to support this mode in naturalistic situations, particularly in the domain of aviation.