Approximate Time (AT) has been proposed as a means for expressing temporal uncertainty in distributed simulation applications in order to enhance parallel performance. This is accomplished by specifying time intervals rather than precise values to indicate when an event might occur. This paper describes a case study in applying AT to a queueing simulation application in order to assess the performance and accuracy that can be obtained using this technique. Up to an order of magnitude speedup was obtained, with error in throughput statistics less than 3%, although somewhat larger error was reported in delay statistics.