During upset operation operators have to deal with a large number of alarms simultaneously. To take the right countermeasures the causes and consequences of the alarms must be known. Distributed control systems do not provide all necessary information, so unexpected disturbances, alarm floods and additional operator actions after upsets are not addressed. This paper presents an operator support system for normal and upset operation, which generates this information. Efficiency, reliability and safety of process plants as well as the operator's situation awareness can be improved.