As a decision making aid for the human operator of a highly automated, complex system, qualitative modeling is presented as a tool to mimic the human global assessment process by learning from the system behavior. Such qualitative model is applied to reason about the behavior of a quantitatively simulated aircraft model, to determine on-line when a malfunction occurs in the quantitative model, to hypothesize about the nature of this malfunction, and to suggest a global strategy that would allow to operate (control) the quantitative aircraft under the modified flying conditions. Such an algorithm could be utilized as an addition to a conventional autopilot which would allow it to remain operational after a malfunction has taken place.