An opening device (1) having an opening part (2) and a stationary part (4). The opening part (2) is movable relative to the stationary part (4) between a closed position and an open position. The opening device further includes a device arranged to accompany the movement of the opening part. The accompanying device has a first part (10) secured to the opening part (2) and a second part (12) secured to the stationary part (4), with the first part (10) being movable relative to the second part (12). The accompanying device includes a safety blocking device (20) arranged to block the movement of the first part (10) relative to the second part (12) when an inertial force applied to the opening part (2) toward the open position is above a predetermined threshold force.