What happened
On 17 July 2000, Alliance Air flight CD-7412 departed from Kolkata's Netaji Subhash Chandra Bose International Airport, heading toward a route including Patna, Lucknow, and Delhi. After a standard departure from Runway 01R, the ATR 72 climbed to FL260. During the flight, the aircraft transitioned through various radar sectors, moving from Kolkata Radar to the Kolkata Area Control Centre, and eventually to Patna Control.
At approximately 0713 hrs, the crew contacted Patna ATC, providing an estimated arrival time of 0736 hrs. The controller cleared the aircraft for a PPT VOR ILS/DME ARC Approach for Runway 25, providing the latest meteorological information which indicated calm winds and haze. The aircraft was instructed to descend to 7500 feet and report its position relative to the PPT VOR. The crew complied with these instructions, reporting 25 DME at 0726 hrs and subsequently descending to 4000 feet.
By 0732 hrs, the flight crew notified Patna ATC of their intention to perform a 360-degree turn because the aircraft was high on its approach. After the controller confirmed the aircraft had the airfield in sight, the crew acknowledged the instruction to report on finals after the maneuver. This was the final communication received from the aircraft.
Shortly after this exchange, the air traffic controller observed the aircraft in a normal descent aligned with Runway 25, though it still appeared to be at a high altitude. The aircraft then executed a steep left turn and suddenly lost altitude, disappearing behind a line of trees. A large plume of smoke was seen rising from the Gardani Bagh area outside the airport perimeter. The accident resulted in 55 fatalities among the passengers and crew, along with 5 deaths on the ground. 3 passengers survived the impact with serious injuries.