Calcutta: Air India will operate a Delhi-Andal flight from April 15 with the departure time pushed back by an hour to 5.50am.

Delhi, the country's busiest airport, had earlier spared a 4.45am departure slot for the flight. Apprehending that seats would remain unsold if the flight took off so early in the morning, Air India had requested the airport authorities for a later slot to make the flight feasible.

For a 4.45am flight, passengers would have had to report at 2.45am.

"DIAL (Delhi International Airport Ltd) has agreed to give us a 5.50am slot and so we will start operations to Andal from April 15," said a spokesperson for the airline.

The flight, to be operated with a 122-seater Airbus A319, will leave Delhi at 5.50am and reach Durgapur at 7.50am. It will take off from Durgapur at 8.25am and arrive in Delhi at 10.35am. The airline is yet to decide on the frequency of the flight - three days or four days a week.

The launch of the flight was confirmed two days ago after the Delhi airport authorities agreed to revise the timing.

Operating flights to and from Andal has been a challenge ever since the greenfield airport near Durgapur opened in 2015. Several airlines have launched flights, only to withdraw them. Air India had withdrawn its Calcutta-Andal-Delhi route in 2016.

The concept of viability gap funding to make up for empty seats hasn't worked. Neither has the state government's offer to waive the surcharge on air turbine fuel bought at Andal airport.

Air India officials said this time there would be no viability gap funding. "We are hoping seats would get filled up this time," said an official.

The state government has requested Air India to operate the Delhi-Andal service for a minimum of 12 months. "But we have not made any such promise," said an official of Air India.