The reasons why accurate measurements are key to reducing the environmental effects of aviation

Using a ubiquitous online search engine, I recently sought to calculate the carbon footprint per passenger of a one-way flight between Paris and New York. The result I obtained was around 1,000 kilograms, i.e. 1 ton, of carbon dioxide emissions. That figure is legitimate and based on a reliable chain of averages. However, each individual flight has a whole range of parameters that mean that the actual figure can vary widely. Let me illustrate why it is important to be able to calculate and capitalize on more detailed data related to the emissions – both carbon and non-carbon – generated by each and every flight.

The generic methods employed, mainly based on aircraft type and fuel consumption, feed into the carbon footprint calculators used by players including ICAO and Eurocontrol, and online resources such as Google Flights. They also serve as a basis to establish the carbon taxes paid by airlines. It should be noted that the data used by the aviation sector solely covers CO2 emissions as declared in the European Trade System, while other sectors – such as the maritime industry – also take non-carbon emissions into account. A general rule of thumb is that to be able to calculate the overall emissions of a flight, the carbon footprint figure has to be multiplied by two.

Working on the basis of global averages is commendable but, as mentioned previously, no two flights are the same. There are onboard parameters to take into account, such as the number of passengers, the amount of luggage, or indeed the amount of cargo if we are talking about cargo aircraft. There are flight parameters to be considered: how fast and how high is the plane flying? There are meteorological factors that enter into play: is the flight assisted by favourable winds or, on the contrary, does it have to contend with strong headwinds? All of these affect levels of fuel burn and therefore carbon emissions.

And then there are the factors contributing to non-carbon emissions. What is the outside temperature? Is the cold air combining with ambient humidity to create contrails, which also produce undesirable greenhouse effects, albeit less longstanding than carbon dioxide? How about nitrogen oxide emissions, which are more or less proportional to fuel burn, and also generate antagonistic effects that can result in atmospheric warming or cooling depending on altitude, area of emission, and weather conditions?

A decision-making aid

At Thales, we have developed an online tool, the Flights Footprint Estimator, which provides airlines and operators with a means to assess flights (and even segments of flights), both past and upcoming, and to aid in taking the decisions that will enable them to make future flights as environmentally-friendly as possible.

As you can imagine, the output data therefore goes far beyond a simple calculation of how much fuel has been burned by a specific aircraft type flying from A to B. Instead it takes into account the various factors I have detailed above: the number of passengers and amount of luggage, meteorological data, and actual flight profile. Trajectory data can be tracked by ADS-B (Automatic Dependent Surveillance-Broadcast) air traffic management stations and radars through the use of onboard transponders. By capitalizing on commercially available ADS-B data, the Flights Footprint Estimator is able to precisely characterize and model every segment of every phase of a flight.

The tool’s predictive capabilities can contribute to decision-making. If operators see that flying at a certain altitude in a certain area will result in the formation of contrails, they can instead opt for a different altitude and an alternative trajectory, in accordance with air traffic control. Today, the general practice is to fly high and use the shortest, most direct route possible to reach a given destination. In the future, this may no longer be the case, and this could even result in difficult decisions having to be made: the most eco-friendly trajectory and flight profile may not necessarily be the most economically profitable for an airline!

With the aviation sector ever more committed to improving its environmental credentials, looking to draw in passengers who are increasingly sensitive to the climate footprint of the flights they take, everything needs to be done to activate, adjust and tweak every possible lever, if aircraft are to continue taking to the air. To be able to precisely assess our impact and act on those findings is therefore the way forward, so let’s get measuring the actual footprint of individual flights!

• Read more about the Flights Footprint Estimator