Sustainability of the National Airspace System (NAS) continues to be a major concern to its governing body, the Federal Aviation Administration (FAA). Several research efforts are addressing the sustainability needs of the future NAS, including the Continuous Lower Emissions, Energy and Noise (CLEEN) program under the FAA, and the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) projects of the National Aeronautics and Space Administration (NASA). These initiatives are focused on developing and maturing technologies that would mitigate the environmental impacts of aviation. Alternatively, the Next Generation air transportation system (NextGen) is to provide substantial efficiency improvements from an operational perspective. Also, bio-fuels continue to be an attractive alternative to conventional jet fuels given their reduced life cycle emissions. This paper proposes an integrated framework that would evaluate the performance of the future NAS under different scenarios that consider varying technology, operation, and biofuel contributions. The objective is to assess whether or not the system level goals laid out by the International Air Transport Association (IATA) will be met.