Disclosed is a method for determining accuracy of a pressure sensor (104) in a respiratory device (100). The respiratory device (100) includes a flow generator (130) which comprises a motor configured to generate a pressurised flow of breathable gas. The method comprises measuring pressure of the flow of breathable gas generated by the flow generator using the pressure sensor (104)； and determining accuracy of the pressure sensor (104) based on the measured pressure and an altitude of the respiratory device using a processor (116).
