A monitoring system 300 for an aircraft 100 including a controller 301 to determine, based on one or more conditions, one or more expected operating characteristics of a steering system of the aircraft. The one or more conditions include one or more aircraft conditions indicative of an internal condition of the aircraft and/or one or more external conditions indicative of an external influence on the aircraft. The controller compares the one or more expected operating characteristics with the one or more actual operating characteristics. The controller is configured to determine, based on the compare, whether to issue a signal indicating a condition of the aircraft. An avionics system 3000 comprising the monitoring system, an aircraft comprising the monitoring system or the avionics system, and a method 600 of monitoring an aircraft.