Different versions of the SET are available. You must use the version applicable for the year in which the flight was operated. Version 5.12.1 is to be used for flights operated in 2022. It replaces version 5.12, which had an incorrect list of available aircraft types. The emissions models in versions 5.12 and 5.12.1 are the same.
The 2022 version of the SET was improved by using linear piece-wise modelling on all aircraft categories when suitable. As a result, almost all aircraft have an improved model. With the voluntary data received in 2022, 35 aircraft models were updated, and 3 aircraft models now have their own actual fuel burn-based model, while in previous versions of the SET they were relying on a generic or equivalent model. Equivalent aircraft were reviewed, 3 new equivalences were created, and 5 equivalences were improved to a closer equivalent model.
The underlying equation in the SET can be obtained by submitting a request using the contact form (the SET equations are subject to a specific data usage agreement).