Cross-polar aircraft trajectory optimization and the potential climate impact

Abstract

Cross-Polar routes offer new opportunities for air travel markets. Transpolar flights reduce travel times, fuel burns, and associated environmental emissions by flying direct paths between many North American and Asian cities. This study evaluates the potential benefits of flying wind-optimal polar routes and assessed their potential impact on climate change. An optimization algorithm is developed for transpolar flights to generate wind-optimal trajectories that minimize climate impact of aircraft, in terms of global warming potentials (relative to warming by one kg of CO 2 ) of several types of emissions, while avoiding regions of airspace that facilitate persistent contrail formation. Estimations of global warming potential are incorporated into the objective function of the optimization algorithm to assess the climate impact of aircraft emissions discharged at a given location and altitude. The regions of airspace with very low ambient temperature and areas favorable to persistent contrail formation are modeled as undesirable regions that aircraft should avoid and are formulated as soft state constraints. The fuel burn and climate impact of cross-polar air traffic flying various types of trajectory including flight plan, great circle, windoptimal, and contrail-avoidance are computed for 15 origin-destination pairs between major international airports in the U.S. and Asia. Wind-optimal routes reduce average fuel burn of flight plan routes by 4.4% on December 4, 2010 and 8.0% on August 7, 2010, respectively. The tradeoff between persistent contrail formation and additional global warming potential of aircraft emissions is investigated with and without altitude optimization. Without altitude optimization, the reduction in contrail travel times is gradual with increase in total fuel consumption. When altitude is optimized, a one percent increase in additional global warming potential, a climate impact equivalent to that of 4070kg and 4220kg CO 2 emission, reduces 135 and 105 minutes persistent contrail formation per flight during a day with medium and high contrail formation, respectively.

Studies of Flight Trajectory Optimization and the Workloads of Air Traffic Control Officers

“…It has been found through experimental results as presented by Ng et al in Equation 12,that fuel consumption is a logarithmic function of the square of density, which is co-related to the minimum drag to altitude ratio found in the above equations (Ng et al, 2011;Ng et al, 2012).…”

“…Referring to Equation 2, changes of SFC with altitude are set to be zero ( = 0), as per discussed using the turbofan's performance characteristic, and only the latter term is to be considered (Ng et al, 2011;Ng et al, 2012).…”

“…is not zero, as density changes with altitude based on the ISA model adopted (which can be found in the later part of this section). Therefore, = 0 for = 0 (Ng et al, 2011;Ng et al, 2012). This would result in the focus being on , which produces Equation 4 (Sun, 2016):…”

“…The papers from (Ng et al, 2011;Ng et al, 2012) showed a relationship, which is expressed in Equation 9:…”

Aviation Turbulence

“…24.1, the longitudinal (λ) and latitudinal (ϕ) position changes of the aircraft with the time in the presence of horizontal winds are governed by the following aircraft-motion equations (e.g., Sridhar et al 2010;Hok et al 2011;Ng et al 2011;:…”