Canadians flying to Europe have been warned to double-check their flight schedules, since European airports have been crippled by unusually harsh winter weather. Thousands of holidays travellers have been left stranded on what is one of the busiest weeks of travel during the year. London’s Heathrow Airport stopped accepting arrivals and allowed only a handful of planes to take off Sunday because maintenance staff were unable to adequately de-ice the tarmac. Airports in France, Italy, Germany and the Netherlands were also closed or experiencing delays. Air Canada says it is only able to operate one-third of its normal schedule through Heathrow, with just six takeoffs and landings allowed Monday. The unexpected shuttering of Heathrow will likely create ongoing delays, with more than a million passengers expected to pass through the airport this week.