KOLKATA: It was a nerve-wracking 30 minutes for 179 passengers and crew on board an IndiGo Airlines flight from Kolkata to Dibrugarh on Thursday as the plane flew through 200km of extreme turbulence with a cracked cockpit windshield.

Flight 6E 205 took off at 12.57pm and hit turbulence almost immediately. Just as the aircraft was heading into clear weather at 35,000ft, the pilots saw the windshield crack. Deciding to return to Kolkata, they put the plane in a dive to lose altitude quickly, ease the pressure and prevent the glass from popping out.

The pilot informed the passengers they were returning to Kolkata because of a technical fault. "There were grumbles in the passenger cabin. We were almost halfway through," recounted Oil India’s H Singh.

The sharp descent and the turbulence increased tension in the cabin. "The loss in altitude was in sudden bursts," said businessman Khaled Khan who was travelling with his mother. "The aircraft would go into a freefall, hold for a while and go into another drop. Passengers already knew there was some problem with the aircraft. The extreme turbulence freaked them out. I began to think about my daughter and pray for mercy. People were either screaming or praying."

Since all the passengers and crew had their seatbelts fastened, there were no injuries. To everyone’s relief, the plane touched down safely at Kolkata airport at 1.59pm. The passengers took off for Dibrugarh in another aircraft at 3.32pm.

According to the airline, there was no danger since only one layer of the three-layered windshield had cracked. An airline official said had the flight gone on to land in Dibrugarh, the plane would have been stranded there till engineers and technicians flew in from Kolkata.