Demand for long-distance transport has been steadily increasing over the last years, worsening the environmental impact of the transport sector. Despite European governmental bodies and policy-makers directed considerable efforts towards the substitution of short-haul flights with greener rail alternatives, the desired results do not appear to have materialised yet. This study contributes to the literature by providing a broad overview of the current state of rail and air service supply in the European market and identifying the most significant nodes and links within the network. Furthermore, the connectivity index proposed by this research allows to compare the performances and the attractiveness of the two modes. Overall, this study shows that air efficiently connects most major European cities, whilst, in the rail network, considerable inequalities in terms of performances across different geographical locations are still present. From this picture, derive two main conclusions. First, the rail network has substantial limitations and constraints on longer distances, and second, the sector is more fragmented and less cohesive than air. To minimise the environmental impact of long-distance transport, it appears beneficial to focus on capturing the demand for connections shorter than 500 km by fostering inter-modality and air-rail integration, enhancing rail performances and opening new competitive direct routes on OD distances longer than 500 km. Currently, rail appears to be more complementary to air, rather than competing with, as the inter-modal competition is limited to shorter routes. However, the results suggest that rail has the potential to be competitive with air also on longer routes, either by offering more direct services, improving schedule coordination, or increasing the supply of high-speed and night train services. In this regard, it is worth noting that more attention should be devoted to analysing the specific infrastructural gaps and the optimal directions for investments. Finally, this paper identifies the main bottlenecks hindering the capacity of rail to compete and substitute air, suggesting that these barriers are not limited but go beyond the network performances and service supply perspectives.