On-time performance is one of the most important Key Performance Indicators for airport operations since flight delays carry a huge economic cost in the industry. Many types of research were conducted to measure aviation delay and its economic cost as consequences (Kuhn, 2013) while environmental impact due to the flight delays was sparsely addressed. Flight delays result in excess fuel consumption and more emission. Existing literature addressed the aggregate emission of the aviation industry(IPCC, 2015). However, assessment of emission levels separately under different phases of flight has not received sufficient attention. Evaluating each phase of flight separately allows initiating more precise emission reduction strategies. In this research, a methodology was developed with technologies to evaluate the flight delays and CO2 emission at the taxing phase for both arrivals and departures. Bandaranaike International Airport (BIA) was taken as a case for developing the methodology.