This paper reviews the existing literature concerned with air passengers with specific access requirements, often referred as passengers with disabilities (PwDs) or passengers with reduced mobility (PRMs). While accessibility in air transport is an emerging field of research, the literature lacks a more in-depth understanding of the barriers that air passengers face, which can guide future research and help practitioners in improving the services to this passenger segment. To this end, we conducted a systematic review of 50 peer-reviewed articles to explore how these challenges have been addressed in existing literature. The analysis expanded upon the established primary barrier categories (architectural, transport, communication and information, attitudinal, and technological). Within these categories, novel sub-groups of barriers were identified and proposed. The analysis further revealed the most suggested solutions to overcoming those barriers: i) legal obligations and standard operational procedures; ii) improving airport facilities and services; iii) digitalization of operations and services; iv) recommendations for improving cabin safety and accessibility; and v) training for airport and airline staff. This study emphasizes the importance of gaining a thorough understanding of the challenges faced by PwDs and calls for more collaborative efforts from various stakeholders to enhance the accessibility and inclusivity of air travel.