evidence: The regional aviation scheme in India had 27 well served and 31 underserved or unserved (total 58) functional airports against the targeted 70 airports at the end of 2018 in phase I of UDAN scheme (Fig. 7). We use the demand and city locations data for these 58 airports to check the efficacy of the scheme across three phases of the scheme. We calculate the Haversine distances between the city pairs. Due to computational burden, our analysis has five, six, or seven well served airports: Delhi (1), Mumbai (2), Chennai (3), Kolkata (4), Bengaluru (5), Hyderabad (6), and Ahmedabad (7). Out of these, airports (1) to (5) are also international hubs. In phase II, 70 airports were functional. However, out of initial 58 airports, only 49 airports were operational for regional connectivity and 21 new airports were added. The regional aviation scheme in India had 96 functional airports and 11 helipads (total 107) by June 2022 after the third phase of the scheme. Ultimately, in phase III, out of the initial 58 airports, 54 airports were operational.