This paper presents an analyis to estimate and characterize the errors in the measured separation distance between aircraft that are displayed on a radar screen to a controller in a single sensor terminal environment compared to a multiple radar mosiac terminal environment. The error in measured or displayed separation is the difference between the true separation or distance between aircraft in the air and the separation displayed to a controller on a radar screen. In order to eliminate as many variables as possible and to concentrate specifically on the differences between displayed separation errors in the two environments, for the purposes of this analysis, only full operation Mode S secondary beacon surveillance characteristics are considered. A summary of the Mode S secondary radar error sources and characteristics used to model the resultant errors in measured separation between aircraft in single and multi-radar terminal environments is presented. The analysis for average separation errors show that the performance of radars in providing separation services degrades with range. The analysis also shows that when using independent radars in a mosiac display, separation errors will increase, on average, compared to the performance when providing separation with a single radar. The data presented in the section on average separation errors is summarized by plotting the standard deviation of the separation error as a function of range for the single radar case and for the independent mosiac display case. The sections on typical and specific errors in separation measurements illustrate that the separation measurement errors are highly dependent on the geometry of the aircraft and radars. Applying average results to specific geometries can lead to counter intuitive results is illustrated in an example case presented in analysis.