Calculating a flight passenger's carbon emissions is complex and challenging as aviation emissions vary on a number of factors.
Weather conditions, aircraft type, flight altitude and range as well as the number of seats and how many of them are occupied play an important role in the calulation of emissions.
For example, tailwinds increase the flight speed and save fuel, while headwinds have opposite effects. Newer planes can be more fuel-efficient than older ones and flying at higher altitudes means thinner air and less friction drag which also reduces fuel consumption.
Moreover, taking off consumes considerably more fuel than cruising which in turn accounts for a larger proportion of the journey for longer flights.
Accurate data for all these factors is often not available which makes it impractical to calculate a passenger's carbon emission share of specific flight journeys.
However, several international airlines publish emission data of their whole aircraft fleet such as the average fuel consumption per passenger of a flight connection.
This real flight data has already factored in above-mentioned unknown variables and therefore allows accurate predictions about the average fuel consumption of flight journeys.
The flight emission calculator operates on large, publicly available real-flight data sets that have been collected from several international airlines.
These data sets are constantly updated to reflect changes in flight emissions due to e.g. more fuel-efficient aircraft fleets.
Moreover, the calculator has been designed to be simple to use requiring only the departing and arrival airport name from the user.
The individual calculation steps are explained in more detail below:
Select the departing and arrival airport of a flight journey
Search the database containing flights from several international airlines for flights with similar characteristics.
Retrieve the fuel consumption per passenger of those flights from the database and compute the average.
This ensures that the predicted fuel consumption does not reflect the values of a single airline but rather approximates the global average.
Convert the burnt jet fuel into carbon dioxide and other greenhouse gas emissions. The conversion is based on the combustion emission factors of kerosene as published by the the United States Environmental Protection Agency.
For example, the carbon dioxide emission factor of jet fuel is 9.75 kg CO2