Private airline IndiGo carried the greatest number of domestic passengers in India in July, says the Directorate General of Civil Aviation, the country’s aviation regulator.

The airline transported 27% of the nearly 4.5 million travelers who flew domestically that month, the regulator said.

India’s private airline Jet Airways and its subsidiary, JetLite, jointly grabbed the No. 2 spot with a 26.6% share, while national airline Air India came in third with 18.2%. SpiceJet was next with 17.8%, followed by GoAir with 7% and cash-strapped Kingfisher Airlines Ltd. with a 3.4% market share.

July data showed that IndiGo carried 1.2 million passengers, Jet Airways 882,000, JetLite 325,000, Air India 824,000, SpiceJet 800,000, GoAir 316,000 and Kingfisher 156,000.

The number of passengers grew 1.74% from January to July compared to the same period in 2011. Overall, domestic airlines carried 35 million passengers between January and July this year, compared to 34 million in 2011.

At a time when the growth of major Indian carriers has been static or slow, low-cost IndiGo has been rapidly expanding its fleet.

Run by InterGlobe Aviation Ltd., IndiGo has a fleet of 58 aircraft, including 50 Airbus A320s that fly domestic routes. The airline has been adding at least nine aircraft yearly, and its fleet size is expected to increase to 60 by year’s end.

IndiGo has offered 63 flights per week this summer, including 28 to Dubai, and secured bilateral rights to fly to Singapore, Bangkok, Jeddah and Kathmandu, a civil aviation ministry official says.

“This is significant in the background of the fact that earlier IndiGo’s total services to international routes were only 53 per week,” the official says.

IndiGo is also expected to launch more international routes by year’s end, the official says.

IndiGo has ordered 100 aircraft since it began operations in 2006 and plans to obtain an additional 180 Airbus A320s over the next few years.

Over the past decade, India air passenger traffic has increased 15%, outpacing 7%-9% growth in the country’s gross domestic product, Civil Aviation Minister Ajit Singh says.

Consequently, airport infrastructure investment also climbed higher than the rate of economic growth, he said.

From 2007-2012, passenger demand stood at 162.3 million, exceeded by an airport handling capacity of 197.7 million passengers, Singh said.

A320 photo: Airbus