Design of Aircraft Trajectories: based on Trade-offs between Emission Sources

Aviation operations affect the climate in several ways. Carbon dioxide, water vapor and other greenhouse gasses are unavoidable by-product of the combustion of fossil fuel. There are indications that persistent contrails can lead to adverse climate change, although the complete effect on climate forcing is still uncertain. A flight trajectory optimization algorithm with fuel and contrails models, which develops alternative flight paths, provides policy makers the necessary data to make trade-offs between persistent contrails mitigation and aircraft fuel consumption. This study develops an algorithm that calculates wind-optimal trajectories for cruising aircraft while reducing the amount of time spent in regions of airspace prone to persistent contrails formation. The optimal trajectories are developed by solving a non-linear optimal control problem with path constraints. The regions of airspace favorable to persistent contrails formation are modeled as penalty areas that aircraft should avoid. The trade-off between persistent contrails formation and additional fuel consumption is investigated for 12 city-pairs in the continental United States. The avoidance of contrails using only horizontal maneuvers results in a small reduction of contrails with increasing fuel consumption. When both horizontal maneuvers and altitude are optimized, a 2% increase in total fuel consumption can reduce the total travel times through contrail regions by more than 70%. Allowing further increase in fuel consumption does not seem to result in proportionate reduction in contrail travel times. This trend is maintained even in the presence of uncertainties in the contrail formation regions such as uncertainties in relative humidity values computed by weather forecast models.

Speaker: Banavar Sridhar, NASA

Room 534