The invention relates to a method for the autocalibration of an inertial rig comprising an inertial core defining a sensor reference frame, implemented in the course of at least two missions (Mn, Mn+1) each comprising the determination, on the basis of measurements of gyroscopes, of the orientation of the rig in a reference frame comprising the north axis (N) and the vertical axis (Up), the method comprising the implementation:—in the course of a mission (Mn), of an estimation (200) of drift errors of the gyroscopes for the orientation of the rig at least with respect to the north axis (dgyrN); and—in the course of a following mission (Mn+1), of a calculation (400) of corrections of drift errors (DXn) of the sensor reference frame (X,Y,Z), on the basis of the estimated drift errors; and—of a calculation (600) of drift errors (Xn+1), consisting in correcting drift errors (Xn) of the sensor reference frame that were calculated during the previous mission (Mn).