International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The accurate determination of test aircraft position and velocity is a very strong requirement in several certification and development flight test applications. This requirement often requires availability of test ranges properly instrumented with optical or radar tracking systems, precision time for data reduction and dependency on environmental and meteorological conditions. The capabilities of GPS (Global Positioning System) technology, in terms of data accuracy, speed of data availability and reduction of test operating cost, moved Bombardier Flight Test Center to make an investment and integrate a system utilizing GPS for extensive use in flight and ground test activity. Through the use of differential GPS (DGPS) procedures, Bombardier Flight Test Center was able to implement a complete system which could provide real-time data results to a very acceptable output rate and accuracy. Furthermore, the system was capable of providing post-processed data results which greatly exceeded required output rate and accuracy. Regardless of the type of aircraft testing conducted, the real-time or post-processed data could be generated for the same test. After conducting various types of testing, Bombardier Flight Test Center has accepted the DGPS as an acceptable and proper flight and ground test measurement tool for its various aircraft test platforms.