The efficiency of the glass cockpit paradigm has faded away with the densification of the aeronautical environment. Today's problem lies with “non-defective aircraft” monitored by “perfectly trained crews” still involved in fatal accidents. One explanation is, at crew level, that we have reached a system complexity that, while acceptable in normal conditions, is hardly compatible with human cognitive abilities in degraded conditions. The current mitigation of such risk still relies on the enforcement through intensive training of an ability to manage extremely rare (off-normal) situations. These are explained by the potential combination of failures of highly complex systems with variable environment & with variable humans. Looking back into the limits and strengths of operators, we have selected very basic knowledge on human cognitive strategies that enabled us to revisit and review our design principles to give back to pilots the ability to stay in the loop: not through the management of more & more complex systems, but by helping them doing what they do best, manage their own resources to make adequate decisions. Basic ground rules regarding human factors are recalled as key references to designers and planners. The paradigm of cognitive resources management is presented as a frame for HMI design. Cognitive strategies that are “naturally” followed by operators to spare their resources are systematically facilitated in AV2020's HMI. A form of “ecological” design is followed, preserving crew cognitive resources and favoring pilots' core abilities: i.e. decision making and application of airmanship.