A method for automatically producing a defined face opening in a longwall mining operation in underground coal mining, using a face conveyor, at least one plow, as an extraction machine, guided on the face conveyor, and respective hydraulic shield support frames having, as main components, a floor skid arrangement, a gob shield, a top canopy and support connection rods. Inclination sensors are disposed on at least three of the floor skid arrangements, the gob shield, the support connection rods and a gob-side region of the top canopy. From the sensors, an inclination relative to a horizontal is ascertained. From the inclination data, by comparison with base data defining a geometrical orientation of the components and movement thereof during a stepping process, a respective shield height of the shield support frames perpendicular to a bed thereof is calculated and is compared with a machine-dependent fixed cutting height of the plow to establish if deviations exist. By means of a boom controller disposed between the shield support frame and the face conveyor, a height control of the plow is initiated to correct established deviations and is maintained, in the sense of a location-synchronized evaluation, until the shield support frame, which trails the plow with a time delay, has reached the position at which the plow was located at the point in time when the height control of the plow was initiated.