a method and apparatus for rapidly detecting acceleration variations in a moving object by monitoring the instantaneous velocity of the object . a signal representative of instantaneous velocity is operated on to derive signals representative of average acceleration , instantaneous acceleration and predicted velocity . the average acceleration and instantaneous acceleration signals are compared to determine acceleration changes . in a preferred embodiment the invention is applied as a wheel slip / slide detector in a traction vehicle and a signal generated when the instantaneous acceleration deviates from the average acceleration by a predetermined magnitude is utilized as a wheel slip / slide signal to implement corrective action to the power control system of the vehicle . upon generation of the wheel slip / slide signal , calculation of average acceleration is inhibited to prevent its influence by the sudden acceleration change . the predicted velocity signal , which is dependent upon the average acceleration signal , is compared with the instantaneous velocity signal to determine when the vehicle has recovered from the wheel slip / slide condition .