The experiment that was setup to determine the feasibility of using sonic ranging to measure the altitude of a small aircraft was successful. Using a sonic pulse with duration of 0.5ms, where the frequency of the pulse emitted was 10 kHz, an echo could be received and identified after reflecting off a surface approximately 52 meters away.  Typical accuracy was in the range of 98.5%.  The estimated price for the components used was $130.  As a result, it has been determined that a sonic range finder may be a viable basis for an inexpensive altimeter.  However, further experiments that simulate actual conditions will need to be run before a final verdict can be reached.