According to the Ministry of National Defence, the accident occurred when Captain Nguyen Thanh Trung was taking an advanced helicopter training session in a Cabri G2. He was in the student’s seat and his instructor was in the pilot’s seat. Radio contact with the helicopter was lost 15 minutes after it took off. The Helicopter Services Company said the helicopter was struck from the rear by a light two-seat Cessna. The mid-air collision killed all four people in the helicopter and the aircraft.