The aviation industry’s environmental impact is large and is forecasted to increase. To counteract this, airlines have adopted a number of sustainable measures such as green economy class, contributions to Sustainable Aviation Fuel (SAF), offsetting and promoting train travel as an alternative to flying. The purpose of this paper is to compare airlines’ approaches to motivate passengers to reduce or offset their journey’s CO2 emissions. A survey was developed with three scenarios (short-, mid- and long-haul flights) and six sustainable measures. The 185 collected responses were analyzed using t-tests and McNemar tests. The results indicate that airlines’ strategies providing more freedom of choice regarding donation amount and more information on the SAF/offsetting scheme can acquire more funds for reducing or offsetting emissions. Further, the train-flight mix is a promising approach to reducing emissions, especially for short- and mid-haul flights, and could be combined with SAF approaches for the largest emission savings.