This proposal targets the improvement of NASA's ground and flight test aeronautics testing capabilities. Potential end users within NASA include ground test facilities such as Western Aeronautical Test Range (WATR) and Flight Loads Laboratory (FLL), as well as flight facilities such as DFRC with both piloted and unmanned systems. Real-time, in-flight data regarding combustor condition and emissions species can provide a previously unavailable test capability for NASA. Monitoring of bleed air for contaminants and fuel backflow is also an area of interest. This technology has military and commercial applications as well, which fits well with NASA's mission for the promotion of advanced technology for civil aviation. Near term, based on input from members of the emissions testing community, there is a need for a lower cost, readily available emissions detection capability for use in engine development and performance measurements. As the sensors and packaging technologies mature, the gas sensor array system might also be used for emissions certification testing for commercial engines. This technology will also apply to in-situ measurement capabilities for coal power plants, industrial burners, boilers, gas turbines, and other engines.