The present invention relates to a method for monitoring a system in which a datum-line display (11) is generated on a viewing screen (4) for at least one parameter of the system, comprising a baseline (14) that represents a base value for the parameter concerned, a continuous curve (15) that represents a variation with time of the values of the parameter concerned and is normal with respect to the baseline (14), and a deviation bar (16) that represents the instantaneous deviation between the base value and current parameter value and is normalized with respect to the baseline (14).