An Arctic blast sweeping across Canada has caused travel chaos as flights are cancelled at major airports ahead of Christmas. WestJet has cancelled all of its flights in and out of Vancouver and Toronto, making for a nightmarish dash home for some travellers. The powerful winter storm, being called a "once-in-a-generation event," is sweeping across Canada, bringing freezing temperatures.This report breaks down the situation at various airports as airlines cancel and delay their services.