The present invention provides a method for controlling an internal pressure in an aircraft or spacecraft, the method comprising the following steps: detecting the internal pressure in the craft and an external pressure Pa outside of the craft and comparing said pressures with each other; and adjusting a flap of at least one outflow valve to a blade position, in which the flap directs air flowing past an outer surface of the craft into the craft to increase the internal pressure, if the external pressure exceeds the internal pressure by a predetermined value during the descent of the craft. The idea, on which the present invention is based, is to assign a double function to the outflow valve: during normal flight the positive pressure in the craft is relieved by means of the outflow valve. During a too steep descent or in case of failure of the air conditioner of the craft, the flap directs air into the craft and thus adapts the internal pressure to the external pressure as soon as it exceeds the internal pressure. Thus, a negative pressure relief valve is advantageously not required and a size thereof can be considerably reduced respectively.