Dum Dum: Calcutta's domestic air traffic will outgrow the current airport in some years but a second one can be built to share the load if the state government provides land, civil aviation minister Ashok Gajapathi Raju said on Tuesday.

"Calcutta needs an alternative airport. This airport is not yet saturated but it will be soon because of the way traffic is growing," Raju said after commissioning a 15MW solar power plant at the airport. "But to build one, we need land. If the state government can provide land, we will build a greenfield airport."

The civil aviation minister specified that the proposed facility would need to be built and run by a private operator. "We will provide the expertise and help the state government get a private party to build and operate it," he said.

Netaji Subhas Chandra Bose International Airport is owned and run by the Airports Authority of India. Chennai is the only other state-owned airport in a metro.

Bengal needs to arrange land, its main bottleneck, within a reasonable distance from the city to build a new airport. "We are talking about thousands of acres here, based on other airport projects. The new airport in Bangalore is spread over 4,500 acres while the one in Hyderabad spans 5,400 acres," said an official in the civil aviation ministry.

State government officials admitted that finding thousands of acres for an airport near the city would be a problem. They recommended Andal, near Durgapur, as the potential second airport that minister Raju said Calcutta would need.

But Andal is almost 200km away, and airlines have not shown any interest so far in operating out of there. "If airlines want to use Andal, there is no problem. But they have to show interest," the civil aviation minister said.

So, how quickly would the city airport need backing up? Officials said growth in domestic flight operations rather than passenger volumes would test the airport. "We have land to build another terminal. Operations can be extended to the old domestic building as well. But the capacity of the runways and parking bays will saturate," airport director Atul Dixit said.

The airport is currently equipped to handle 30 flights every hour. The target is to handle 35 flights an hour, which with a scale-up in capacity can go up to a maximum of 42, officials said.

In terms of flights, the daily average is 415, which works out to a little more than 17 flights an hour. The airport's domestic traffic grew 26 per cent last year.

According to officials, the problem is that all airlines want flight slots during the morning and afternoon peak hours. The airport has two runways but these cannot be used simultaneously. A minimum distance of 760 metres is required between the two runways for simultaneous use. Land constraints means a third one cannot be built.