Dec. 29: Calcutta airport has an integrated terminal with segregated security holds for domestic and international operations, leaving one half overflowing for most of the day and the other section underutilised.

The state-run airport apparently hasn't found a way yet to break the glass - literally and figuratively - and make the entire terminal available for optimum usage, something private airports across India are doing.

The airport has 18 aerobridges, nine of them for the domestic section. Two of the other nine are for common use.

In Mumbai, the new terminal has about 50 aerobridges. "There is provision for all these boarding bridges to be used for domestic or international flight operations, depending on demand. Passengers can be moved through swing doors from one section to another," said an official of Mumbai International Airport Ltd.

Since Calcutta airport's integrated terminal has no such provision, long queues and delayed flights are common in the domestic section. Morning flights often get delayed by five to 10 minutes because of the boarding bottleneck, airline officials alleged.

A senior official said it was not possible to use the aerobridges meant for international flights to speed up domestic operations. "This segregation is required for security reasons. It is technically not possible to have aerobridges for common use because of customs and immigration issues."

Airport director Atul Dixit blamed airlines for the chaos. "Airlines should bring aircraft parked in the remote bays at night to the aerobridges. That will reduce congestion. We have written to them about this. They should also maintain on-time performance to avoid such chaos," he said.

When the new terminal became operational in March 2013, the airport authorities had said it could handle 20 million passengers annually. The terminal currently services about 13 million passengers and yet there is congestion at some points, for which airlines blame what has been the bane of this airport: red tape.

The number of domestic flights from the city has increased to 157 from 112 last year. There has also been a 14 per cent increase in the number of passengers.

Apart from these factors, most flights to destinations like Delhi, Mumbai and Bangalore have been going almost full the past few weeks because of the holidays. The surge in traffic has added to the chaos.

When the number of boarding bridges available for domestic flights prove inadequate, airlines line up coaches outside the ground-floor gates to take passengers till the aircraft the old-fashioned way.

But there's a hitch. Of the five boarding gates on the ground floor of the terminal's domestic section, two don't have the requisite infrastructure for accurate and quick recording of passenger data.

"If you create infrastructure, its use should be optimum. At Calcutta airport, there is room for improvement in this regard. There is congestion as well as confusion at the bus boarding gates whenever passengers of several flights have to simultaneously board through the same gate," said Captain Sarvesh Gupta, chairman of the airline operators' committee at the airport.

"This delays flights and there is also a chance that a passenger may mistakenly reach the wrong plane," he said.

An official said there was a plan to install three aerobridges in the old domestic terminal along with an air-conditioned corridor linking it to the new facility. Work could start next year, he added.