A target is located and a track is associated with the target in the fusion coordinate system. An estimate/prediction of the target's velocity is developed within the tracker, as well as , a vector representing the distance from the fusion center to the target as estimated by the tracker, and , a vector representing the known distance from the fusion center to the sensor. The sensor's range vector, (the distance from the sensor to the target as predicted by the tracker) is transformed to fusion coordinates. Using the sensor's range vector, normalized to unit length, in fusion coordinates and the estimated target's velocity, an estimate of the target's speed projected in the direction of is derived. The estimated range-rate is compared per update to the sensor's measured range-rate in the form of an error measurement. The error is then used to correct the track's velocity prediction.