In short




2020-06-01 > 2022-11-30






As much the goal of reducing carbon emissions is important, the warming impact of aviation caused by the other chemicals emitted by jet engines should not be overlooked. For example, the emissions of water vapour that form the contrails we see in the sky may seem harmless (what harm can water do?). In fact, when the atmosphere’s suspended ice content in high aircraft contrails do not dissipate; persistent contrails trigger a chain reaction that leads to what is known as aviation-induced cloudiness, which typically have a warming effect on the climate. In addition to water vapour, flying aircraft also release nitrous oxide (NOx) and particulate matter.

The effects of these non-CO2 emissions are strongly dependent on weather and vary considerably according to atmospheric conditions, such as air temperature and altitude. It is estimated that they may account for as much as two thirds of the impact of aviation on climate change, with the other third being CO2. The good news is that the impact of non-CO2 emissions is dependent on the atmospheric conditions at the exact place where the aircraft is.

A small deviation to the route of a flight can make all the difference, for example, by avoiding areas of persistent contrails in favour of areas where contrails dissipate quickly. This is where ATM can provide enormous relief.  

The FlyATM4E project modelled these climate impact metrics in multiple environments including trans-Atlantic routes, and explored the feasibility of a concept for aircraft avoiding the more sensitive areas, otherwise known as “big hits”. Their modelling found that in most cases it should be possible to apply effective re-routing strategies in support more eco-efficient routes and climate-optimised aircraft trajectories

FlyATM4E identified those weather situations and aircraft trajectories, which lead to a robust climate impact reduction despite uncertainties in atmospheric science that can be characterised by ensemble probabilistic forecasts. Planning of these climate-optimised aircraft trajectories requires that air traffic management uses spatially and temporally resolved information on the magnitude of the climate effects associated to aviation emissions during the trajectory planning process. 

The FlyATM4E solution relies on prototypic algorithmic climate change functions (aCCFs) to derive such climate impact information for flight planning directly from operational meteorological weather forecast data. By combining the individual aCCFs of water vapour, NOx, contrail-cirrus, i.e. merged non-CO2, it becomes possible to generate aCCFs that describe the overall climate impact of non-CO2 aviation emissions and identify weather situations with high mitigation potential, including an uncertainty assessment. The analysis of sample flights showed different changes in average temperature response with respect to cost or climate optimum and trade-off trajectories within the set of pareto-optimal solutions. 

These results suggest that applying these enabling solutions have the potential to reduce the aviation climate footprint by low or no additional costs.  

Watch from minute 8'30"


Deutsches Zentrum für Luft- und Raumfahrt e.V. (Coordinator)

Technische Universiteit Delft

Technische Universität Hamburg

Universidad Carlos III de Madrid

This project has received funding from the SESAR Joint Undertaking under the European Union's Horizon 2020 research and innovation programme under grant agreement No 891317

European Union