Abstract: A method for automatically producing a defined face opening in a longwall mining operation, in underground coal mining, having a face conveyor, at least one extraction machine and hydraulic shield support frames. Inclination sensors are disposed on at least three of the four main components of each shield support frame, such as floor skid, gob shield, support connection rods and gob-side area of the top canopy. From ascertained inclination data, by comparison with base data defining a geometrical orientation of the components and a movement thereof during stepping, a respective shield height of the shield support frames perpendicular to a bed thereof is calculated. From further sensors on the extraction machine, a cutting height thereof is acquired as a face opening.