I keep mentioning willingness to pay studies. Here are a few examples. You would want to use a validated scale that is published in a peer reviewed journal as your dependent variable’s measure. One of these might work, and they will give you an idea of what you could do in a similar design but focused on SAFs (e.g., pay X, Y, or Z % more for SAF fuel, OR which are consumers willing to pay more for- SAF or carbon offset of their flight?). Reading about what others have done on somewhat-related topics can also help you see methods and/or figure out exactly how you want to define your research problem. If you compared willingness to pay for SAFs and carbon offsets, you would need to review some of the research on carbon offsets. If you only focus on SAFs, then there is no need to review carbon offset research.
Rice, C., Ragbir, N. K., Rice, S., & Barcia, G. (2020). Willingness to pay for sustainable aviation depends on ticket price, greenhouse gas reductions and gender. Technology in Society, 60, 101224.
Cordes, H., Baumeister, S., & Käyrä, M. (2024). Factors influencing the willingness to pay for aviation voluntary carbon offsets: А literature review. European Journal of Tourism Research, 36, 3602-3602.
Xu, B., Ahmad, S., Charles, V., & Xuan, J. (2022). Sustainable commercial aviation: What determines air travellers’ willingness to pay more for sustainable aviation fuel?. Journal of Cleaner Production, 374, 133990.