In this study, a comparison in terms of environmental impact is carried out between regional jet and narrow-body passenger aircraft with different Maximum Take-Off Weights (MTOW) and seating capacities considering the fuel burn and emissions. The flight trajectory is selected from Erzincan Yıldırım Akbulut Airport to Ankara Esenboğa Airport and that trajectory is a frequently performed domestic flight between Erzincan and Ankara. Integrated Aircraft Noise and Emissions Modelling Platform (IMPACT) developed by EUROCONTROL is used for the calculation of fuel burn, CO2, H2O, and other gas emissions (NOx, SOx, CO, HC, soot, and other trace compounds) for the per phase of flight. These emissions have an impact on human health, air quality, and the ecosystem, and cause air pollution, climate change, and global warming worldwide. Commercial air-transport-based simulations are created for regional jet and narrow-body passenger aircraft. According to the results, flying with regional jets which have lower MTOW from/to airports such as Erzincan Yıldırım Akbulut Airport, where the passenger density per aircraft is low, provides advantages in terms of fuel burn and emissions. It is expected that this study will serve as a guide for airline operators for fleet selection based on fuel burn and emission parameters.