A Preliminary Study on Relationship between Flight Path Angle and NOx Emissions during Descent

Interest in the continuous descent approach has recently increased due to opportunities it provides for fuel savings and emissions and noise control. However, the implementation of this procedure involves a number challenges not easily addressed with current technology. Generally, the continuous descent approach has been examined through the reduction in fuel consumption and descent time. However, in this study, the effect of continuous descent approach with various flight path angles, along with a number of flight performance parameters, on nitrogen oxides are investigated. Using actual flight data records of ten B737-800 commercial aircraft, it is shown that with flight path angles of 2.25 degrees- 4.25 degrees, which are considered in the high flight path angle category, differ in terms of fuel flow, specific range and emission production patterns, compared to descents with flight path angles of 1.25 degrees- 2.25 degrees (low flight path angle category). In addition, the emission production pattern is quantified with respect to descent altitude, since the effect of flight path angle varies with altitude.