A ventilation apparatus for artificial ventilation of a patient, having - a respiratory gas source; - a ventilation conduit arrangement proceeding between the respiratory gas source and a patient-side proximal end; - a valve arrangement (20, 22) encompassing an inhalation valve and an exhalation valve; - a flow sensor arrangement (44, 48) for quantitative detection of a gas flow in the ventilation conduit arrangement, encompassing a distal flow sensor arranged farther from the patient-side end of the ventilation conduit arrangement, and a proximal flow sensor located closer to the patient-side end of the ventilation conduit arrangement; - a pressure sensor arrangement for quantitative detection of a gas pressure of gas flowing in the ventilation conduit arrangement; - a pressure modification arrangement for modifying the gas pressure of the gas flowing in the ventilation conduit arrangement; and having - a control device that is embodied at least • to control the operation of the pressure modification arrangement on the basis of measured signals of the proximal flow sensor, and • to infer a fault in the proximal flow sensor as a function of measured signals of the proximal flow sensor and of the distal flow sensor, characterized in that the control device is embodied to infer, as a function of measured signals of the proximal flow sensor and of the distal flow sensor, namely based on the detected flow values and/or on the volume values determined therefrom of the proximal flow sensor and the distal flow sensor approaching each other according to amount, a candidate fault in the proximal flow sensor, and to infer a fault in the proximal flow sensor only with a time delay after identification of the candidate fault, the control device being embodied to reject the candidate fault if, during a verification phase that begins with or after identification of the candidate fault, at least one rejection criterion, taking into account a degree of spontaneous respiration activity by the patient, for rejecting the candidate fault is met. - a respiratory gas source; - a ventilation conduit arrangement proceeding between the respiratory gas source and a patient-side proximal end; - a valve arrangement (20, 22) encompassing an inhalation valve and an exhalation valve; - a flow sensor arrangement (44, 48) for quantitative detection of a gas flow in the ventilation conduit arrangement, encompassing a distal flow sensor arranged farther from the patient-side end of the ventilation conduit arrangement, and a proximal flow sensor located closer to the patient-side end of the ventilation conduit arrangement; - a pressure sensor arrangement for quantitative detection of a gas pressure of gas flowing in the ventilation conduit arrangement; - a pressure modification arrangement for modifying the gas pressure of the gas flowing in the ventilation conduit arrangement; and having - a control device that is embodied at least • to control the operation of the pressure modification arrangement on the basis of measured signals of the proximal flow sensor, and • to infer a fault in the proximal flow sensor as a function of measured signals of the proximal flow sensor and of the distal flow sensor, • to control the operation of the pressure modification arrangement on the basis of measured signals of the proximal flow sensor, and • to infer a fault in the proximal flow sensor as a function of measured signals of the proximal flow sensor and of the distal flow sensor,