The invention relates to a monitoring system (1) for an aircraft for monitoring mobile accessory devices (2) in the aircraft, in particular rolling containers for an on-board kitchen of the aircraft, comprising at least one stationary sensor device (3) for detecting one of the mobile accessory devices (2) and comprising a central unit (10) for evaluating a current security state of the mobile accessory devices (2) based on detection results (DS) of the at least one stationary sensor device (3) reported to the central unit (10). The monitoring system (1) also comprises at least one mobile sensor device (4) for detecting any accessory device (2) of the mobile accessory devices moving relative to the mobile sensor device (4) within a predetermined distance (E), and for reporting a respective detection result (DM) to the central unit (10). In addition, the central unit (10) is designed for evaluating the current security state of the mobile accessory devices (2), taking into consideration the detection results (DM) of the at least one mobile sensor device (4). The invention also relates to a corresponding monitoring method.