A tachymetric anti-aircraft fire control system generates target position, speed, direction, and rate of target range change, by computing these parameters directly from measured data. The target's range, height and observed bearing data is fed into a computer which uses the measured change in range, height and bearing from successive observations of the target to compute the true range, direction, speed and rate of climb or descent of the target. The computer then calculates the required elevation and bearing of the AA guns to hit the target based upon its predicted movement.