Abstract: A diagnostic system of an aircraft, comprising a plurality of sub-systems at least one of which performs monitoring and notification of at least one detected event, using graphs of feared events. After a message of notification of occurrence of the detected event has been received, a set of feared events linked to this message is created from the graph of feared events, and logic expressions are constructed according to logic links represented in the graph of feared events. A group of feared events then is created according to elements of the logic expressions. The minimal vertexes of the logic expressions associated with the feared events of the group are calculated and form a diagnosis of the system.

Abstract: The invention in particular has as an object aid in diagnosis of a system of an aircraft, comprising a plurality of sub-systems at least one of which comprises means for monitoring and notification of at least one detected event, using graphs of feared events. After a message of notification of occurrence of the said detected event has been received (500), a set of feared events linked to this message is created (510) from the said graph of feared events, and logic expressions—using as operands elements of the system coherent with the feared events of the said set—are constructed (515) according to the logic links represented in the said graph of feared events. A group of feared events then is created (520) according to elements of the said logic expressions. The minimal vertexes of the logic expressions associated with the feared events of the said group are calculated and form a diagnosis of the said system.