The mid-air collision between a helicopter and a light aircraft, which killed four people near Waddesdon Manor in Buckinghamshire nearly two-years-ago, has been ruled as an accident, BBC reported. An Air Accidents Investigation Branch report said the aircraft were in each other's blind spots, BBC quoted an inquiry at Beaconsfield Coroner's Court. The incident, which dates back to November 17, 2017, led to the death of Jaspal Bahra, 27, Saavan Mundae, 18, Mike Green, 74, and Nguyen Thanh Trung, 32. Both aircraft had taken off from Wycombe Park Airfield at about 11:45 GMT. Capt Green was in the helicopter giving a lesson to Vietnamese military officer Capt Trung while Bahra, a flight instructor, was giving a lesson to Mundae, a student from Richmond, in the plane Cessna 152. An eyewitness to the incident said that she saw the two aircraft coming down and thought "it was just aerobatics". "They dropped together and dropped out of my sight. I stood there gobsmacked. It was all unreal," she said. The post-mortem examinations of the men revealed that they died from multiple injuries. (With inputs from BBC)