Persistent contrails mitigation strategies

Introduction, Motivation and Goal

The goal of this research is thus to find contrail mitigation strategies with new flight planning concepts. CO2 is the most widely perceived greenhouse gas agent in aviation. However, emissions from aircraft engines include other constituents that contribute, via the formation or destruction of atmospheric constituents, to climate change. Another source of aviation-induced climate change comes from the formation of persistent contrails, which are composed of ice particles and formed in the wake of jet aircraft at high altitude where the ambient temperature is very low. Quantifying the climate impact of persistent contrails is an area that has attracted considerable research interests over the past decades. While consensus has yet to be achieved, the general conclusion is that the magnitude of contrail climate impact is non-negligible compared to that of CO2. Several strategies for persistent contrail mitigation have been studied. We focus herein on flight planning concepts for contrail mitigation. Further mitigation potential can be achieved by developing optimized aircrafts and jets for these alternative trajectories.

Figure 3. Persistent contrails

Figure 3. Persistent contrails

Employed Techniques

Mixed-integer linear programming allows many constraints to be considered and relatively large problems to be solved, permitting for instance the solution to realistic ATM de-conflicted, multi-aircraft scenarios. On the contrary, it is well-known that the most complete way of solving a trajectory optimization problem is to formulate it as an optimal control problem. Therefore, a bi-level algorithm is used pertaining:

  • Optimal control to obtain the individual aircraft environmentally friendly trajectory.
  • Mixed-integer linear programming algorithms to analyze the problem at a network level.

Moreover, Global Warming Potential theory is used to find metrics and thus quantify the impact of different climate impact sources.


Accounting for the formation of persistent contrails, therefore, should be indispensable when one wants to mitigate the overall aircraft induced climate impact. Preliminary results show that different optimal vertical profiles arise from different CO2-contrails trade offs.

Relevant Publications


  • Flight Trajectory Design in the Presence of Contrails: Application of a Multiphase Mixed-Integer Optimal Control Approach. M. Soler, B. Zou, M. Hansen. Transportation Research Part C: Emerging TechnologiesVolume 48, November 2014, Pages 172–194 DOI 10.1016/j.trc.2014.08.009