Air India group most frequent flyer on 7 of 10 busiest domestic routes

Also runs IndiGo close on the other three

The Air India group -- which comprises Air India, Vistara, Air India Express, and AirAsia India -- is the biggest operator on seven of the top 10 busiest routes in India. But it remains a distant number two, after IndiGo, in the overall domestic market.

The Tata group and Singapore Airlines (SIA) announced on Tuesday that Vistara will be merged with Air India to create a single full-service airline, with SIA holding a 25.1 share in the new entity. AirAsia India is already in process of merging with Air India Express to create a single low-cost subsidiary of Air India.