In this study a novel method is developed to identify the NOx emissions released from commercial aircraft during descent. In order to obtain EINOx the real flight data and ICAO emissions database are used. According to the results, statistically significant models are found and the NOx emissions produced from aircraft are calculated to be higher compared to those obtained by ICAO EINOx. Also, the effects of vertical profile, EGT and N1 are discussed. Overall, the minimum and maximum NOx emissions released from the descent of ten flights are calculated as 2.4 kg and 7.2 kg for model 3, with 1.5 kg and 5.4 kg for the baseline, respectively.