A method of operating a sealing station of a packaging machine for producing, in the case of possibly varying filling degrees, packages with at least substantially similar package appearances, the method comprising the following steps: • filling a free package volume enclosed between a lower and an upper packaging material (8, 10) and defined by at least one package positioned within the sealing station with a gas, intended to be used for creating a desired atmosphere, from an initial pressure prevailing in the package volume up to a predetermined gas flushing pressure, • detecting, at least temporarily during filling of the package volume, a pressure curve by means of at least one pressure-detecting sensor system connected to the package volume, the pressure curve being preferably detected on the basis of a time-dependent pressure curve (K IST) between the initial pressure and the predetermined gas flushing pressure, • comparing the detected pressure curve with a reference pressure curve detected preferably on the basis of a pressure curve (K REF), which, in turn, is time-dependent, for filling a known free reference package volume (P REF) of at least one, in particular empty reference package (V REF) positioned within the sealing station with the gas between the initial pressure and the predetermined gas flushing pressure, • calculating a filling degree of the package positioned within the sealing station on the basis of the comparison between the detected pressure curve and the reference pressure curve, and/or a volume flow on the basis of the comparison of the detected pressure curve with the reference pressure curve, and • setting at least one process parameter at the packaging machine with due regard to the calculated filling degree and/or volume flow. • filling a free package volume enclosed between a lower and an upper packaging material (8, 10) and defined by at least one package positioned within the sealing station with a gas, intended to be used for creating a desired atmosphere, from an initial pressure prevailing in the package volume up to a predetermined gas flushing pressure, • detecting, at least temporarily during filling of the package volume, a pressure curve by means of at least one pressure-detecting sensor system connected to the package volume, the pressure curve being preferably detected on the basis of a time-dependent pressure curve (K IST) between the initial pressure and the predetermined gas flushing pressure, • comparing the detected pressure curve with a reference pressure curve detected preferably on the basis of a pressure curve (K REF), which, in turn, is time-dependent, for filling a known free reference package volume (P REF) of at least one, in particular empty reference package (V REF) positioned within the sealing station with the gas between the initial pressure and the predetermined gas flushing pressure, • calculating a filling degree of the package positioned within the sealing station on the basis of the comparison between the detected pressure curve and the reference pressure curve, and/or a volume flow on the basis of the comparison of the detected pressure curve with the reference pressure curve, and • setting at least one process parameter at the packaging machine with due regard to the calculated filling degree and/or volume flow.