To respond to consumers’ rising concerns about environmental topics, airlines increasingly use green advertising. However, due to the environmental impact of flying, many green advertisements by airlines can be considered as “greenwashing” practices. In an experimental study with a quota-based sample (N = 329), we investigated the effects of two types of greenwashed advertisements for airlines: concrete compensation and abstract compensation (compared to a control condition). Following the Elaboration Likelihood Model (ELM), we also explored the moderating role of environmental knowledge in the ability of consumers to perceive greenwashing in airline advertising. Results indicated that concrete compensation claims did not increase greenwashing perceptions compared to the control condition. However, abstract compensation claims did, which, via perceived greenwashing, were negatively associated with brand outcomes and assessments of flying. Environmental knowledge did not moderate these effects. Implications for research on greenwashing, as well as practical conclusions for environmental communication, are discussed.