In recent years there has been increasing interest in the environmental impacts of aviation, and some airlines have begun to address this issue more seriously. At the same time competition in the aviation industry has become much tougher. This study focuses on the question whether showing pro-active environmental behaviour could work as a differentiation strategy for airlines which are acting more responsibly, thus helping them to improve their competitiveness. For this purpose one airline showing strong pro-environmental behaviour in recent years was chosen as an example: Finland’s flag carrier, Finnair. This paper presents the results of a questionnaire conducted among 148 Finnair customers on their opinions and attitudes towards environmental aspects of flying, such as a modern and fuel-efficient fleet, direct flights, carbon offset, and emissions calculators. The results showed that indeed there are air passengers who consider the environment when booking a flight, although this was not the majority. The study also found that the participants saw additional value in a modern fleet and direct flights, but not all of them were ready to pay any extra for that.