A Canada-bound airliner was forced to make an emergency landing after severe turbulence injured 21 passengers, including three children, officials said.<br />The Air Canada flight from Shanghai to Toronto was diverted to Calgary after the turbulence hit.<br />Eight passengers suffered neck and back injuries and 13 more were taken to hospital for observation.<br />The injured were in a stable condition, an emergency services spokesman said.<br />Bing Feng, a passenger, described hearing "lots of screaming" as the plane became "like a rollercoaster".<br />Another passenger, Yi Lee, said: "To start with it was just OK, normal just up and down, and all of a sudden it was really violent and just shaking everybody.
