This decision aid method includes the following steps: acquiring (110) operating states of systems, the operating states being determined by a monitoring system; determining (120) an availability state of each operational capacity, based on the operating states of only the systems of the aircraft implementing that operational capacity, each availability state being chosen from among the group consisting of: a normal state, a downgraded state, an impacted state and a lost state; selecting (150) one or more operational capacities based on the current movement context of the aircraft; communicating (150) the availability state of each selected operational capacity to the pilot.