A gas distribution system in an airplane has improved reliability of operation with a first supply line (7) and a second supply line (9) for pressurized gas connected to a pressurized gas source (2) via a branching site (6) with a second shut-off valve (10). The pressure in the supply lines (7, 9) is determined with a pressure-measuring means (24). An evaluating device (24) for the measured pressure signal is provided for sending a closing signal to the shut-off valve (8, 10) of the supply line (7, 9) in which a pressure drop of consequence occurs.