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 encompassing an inhalation valve and an exhalation valve ; - a flow sensor arrangement 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 encompassing an inhalation valve and an exhalation valve ; - a flow sensor arrangement 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 , <EOS>