In this research the authors sought to better understand the formal and informal (social media) communication channels utilised by 28 airlines worldwide. The primary motivations focused on how the airlines communicate sustainability and corporate social responsibility (CSR) initiatives to stakeholders, and the resulting impact, if any, on corporate reputation. To better align the stakeholder segments of the airlines, the airlines were segmented into two categories: full-service carriers (FSCs) and low-cost (no frills) carriers (LCCs). Data analyses from 28 airlines worldwide were conducted to determine whether FSCs or LCCs gain higher engagement in their formal and informal communication of CSR/ sustainability initiatives. Although the results were mixed, the study finds that, regardless of type of airline category, the communication of CSR/sustainability efforts enhances stakeholder engagement and improves corporate reputation regardless of type of communication channel. These findings, which transcend the aviation sector, highlight the importance of using both formal and informal channels to communicate inter alia customer service initiatives. Highlights include the application of CSR/ sustainability social media communication practices to a selected group of international airlines and how such practices correlate with the United Nations’ Sustainable Development Goals, in the airline context. Finally, based on the research results, the paper presents recommendations to improve the communication of CSR/sustainability goals and hence corporate reputation.