Abstract: An active control of a vehicle occupant's body in a frontal collision including a double-acting hydraulic cylinder connected between a vehicle seat frame and a vehicle frame upon which the seat frame is slidabley mounted for movement in a longitudinal direction relative to the vehicle. The seat frame is releasably fixed to the vehicle frame by a solenoid actuated detent controlled by a microprocessor electrically connected to an accelerometer. A linear variable differential transformer measures the linear position of the seat and a rotary variable differential transformer measures the angular motion of the occupant's body. The transformers transmit signals to the microporcessor which in turn transmits signals responsive thereto to a directional control valve which controls the hydraulic fluid supplied to and exhausted from the double-acting hydraulic cylinder for controlling the forward sliding movement of the seat depending upon the severity of the impact level.