Many factors go into calculating the emissions impact of flying, and each methodology makes certain assumptions on the factors that matter (or do not). Ultimately, calculating emissions isn't an exact science, and none of the methods is "right" in any absolute sense. The correct question then is whether the estimates are right within the context of decisions that they drive. Lumo's APIs and reporting solutions deliver data using multiple methodologies – including Defra, ICAO, and our own proprietary calculations – to ensure you have the right data for your use case.