Elevator system comprising at least one moving object configured for traveling along at least one guide member extending between a plurality of landings ; a position sensor configured for determining the current position of the moving object along the guide member ; at least one elevator safety device mounted to the moving object comprising: a safety controller ; a memory ; at least one engagement member movable between a non-actuated state in which it does not contact the guide member ; and an engaged state in which it engages with the guide member ; and at least one actuation member mechanically coupled with the at least one engagement member and movable between a non-actuated state; and an actuated state; characterized in that the at least one actuation member does not contact the guide member in the non-actuated state; the at least one actuation member contacts the guide member in the actuated state; and in that the safety controller is configured for: causing the at least one actuation member to move from the non-actuated state into the actuated state and storing within the memory a position of the moving object detected by the position sensor at a point of time within a given time frame around the moment in which the at least one actuation member is caused to move from the non-actuated state into the actuated state as a starting position; detecting the position of the moving object along the guide member after the actuation member has been moved from a non-actuated state into the actuated state; calculating the distance (d) between the detected position and the starting position; and determining that the elevator safety device has entered a fully activated state, in which the at least one engagement member engages with the guide member , when the calculated distance (d) between the detected position and the starting position reaches or exceeds a predefined limit. a safety controller ; a memory ; at least one engagement member movable between a non-actuated state in which it does not contact the guide member ; and an engaged state in which it engages with the guide member ; and a non-actuated state in which it does not contact the guide member ; and an engaged state in which it engages with the guide member ; and at least one actuation member mechanically coupled with the at least one engagement member and movable between a non-actuated state; and an actuated state; the at least one actuation member does not contact the guide member in the non-actuated state; the at least one actuation member contacts the guide member in the actuated state; causing the at least one actuation member to move from the non-actuated state into the actuated state and storing within the memory a position of the moving object detected by the position sensor at a point of time within a given time frame around the moment in which the at least one actuation member is caused to move from the non-actuated state into the actuated state as a starting position; detecting the position of the moving object along the guide member after the actuation member has been moved from a non-actuated state into the actuated state; calculating the distance (d) between the detected position and the starting position; and determining that the elevator safety device has entered a fully activated state, in which the at least one engagement member engages with the guide member , when the calculated distance (d) between the detected position and the starting position reaches or exceeds a predefined limit. <EOS>