A height-monitoring system has been proposed for measurement the geometric height of aircraft, which would support reduction of vertical separation minima. This system obtains aircraft track data to estimate its height by using two radars in which the pulses are radiated asynchronously. Prior to height estimation, it is required to extract track data on one aircraft in order to collate the track data obtained by the two radars when several aircraft are in the surveillance area. This paper proposes a method of collating track data. In this method, some parameters are first extracted from each set of track data and then the corresponding tracks are identified on the basis of decision criteria. The criteria comprise comparison of the difference in estimated parameters and an estimate of its standard deviation multiplied by a constant. A computer simulation using pseudo-track data for testing the effectiveness of the method has been done. This paper describes the verified method and some features of the distribution of estimated parameters.