flights
In determining the ecological impact of flights, there are many factors. Focusing on GHG emissions, the following aspects have the biggest influence on your impact:
1. Flight duration
2. Class
3. Route factor
Flight duration
The flight duration determines the altitude and speed of the plane, which impacts the emissions.
Take-off and landing are very emission intensive, but in long-range flights, there is an increased greenhouse effect of emissions due to high altitude. Short-range flights fly at lower altitudes.
Class
The class is relevant because of the space. People flying first class enjoy extra comfort and space that would otherwise be used for several economy seats increasing the emissions of the first class passenger.
Route factors
When taking a round trip the emissions double.
Elements of uncertainty concerning flights are connections and layovers, as a 12-hour direct flight has a different emission than flying 12 hours with 2 short-range and a medium-range flight.
More information can be found here:
https://soep-online.de/assets/files/Fluggastrechte/Verordnung%20(EG)%20Nr.%20261-2004.pdf
https://www.umweltbundesamt.de/sites/default/files/medien/publikation/long/3327.pdf