The model for calculations of emissions from flights is based on NTM’s (Network for Transport Measures) model for carbon emissions, which takes the following factors into account:
- Origin
- Destination
- Aircraft type
- Cabin factor
The cabin factor describes how the full the plane is, which, along with aircraft type, impacts the emissions per passenger. Because the user rarely has access to the cabin factor or aircraft type, we use NTM’s standard values, which are in turn based on data from the International Civil Aviation Organization (ICAO).
If the trip includes stopovers, each leg is calculated individually, because the takeoff and landing have a large effect on the emissions. For each leg, the distance is calculated with the large circle distance between the airports, based on their latitude and longitude.
The total CO2 emissions are then calculated with fixed values for takeoff and landing plus a variable value based on the distance. The takeoff and landing values are unique for each combination of aircraft and cabin factor. The CO2 emissions are then divided by the number of passengers resulting from the aircraft’s capacity and cabin factor.
Emissions from aircraft at high altitude have a larger climate impact than emissions at ground level, which is especially important for longer flights. Therefore, emissions that occur when the aircraft is at a high altitude are multiplied by a factor called the Radiative Forcing Index (RFI) to take into account these effects. Most scientific estimations put the value of the RFI somewhere between 1 and 4. We apply a factor of 1.9 based on a report by researchers at Chalmers (Kamb et al, 2018).
Calculate emissions from air travel here.
