Thousands of passengers were stranded in America after flights to Britain were grounded as snow battered the US east coast.
British Airways, Virgin Atlantic, Delta Air Lines, United Airlines, American Airlines and Air Canada were all forced to cancel scheduled flights, Heathrow said. Passengers were advised to check if their flights are affected with their airlines.
British Airways said affected passengers with accommodation near the US airports were advised to go back home, while others were put up in hotels.
The eastern seaboard was left shrouded in a deep layer of snow, which stranded drivers on roads and piled up drifts so high that some homeowners could not open their doors. More than 650,000 homes and businesses were left without electricity.
Airlines cancelled more than 5,300 flights across the country, although the three major airports serving New York City were allowed to operate some flights. Flights were expected to be close to operating normally on Sunday.
At least six deaths were blamed on the storm, including three in Canada.
A little more than 11 inches fell in New York, but the city was "in great shape" and "dodged a bullet," Mayor Michael Bloomberg said, predicting streets would be cleared by the end of the day.
Hundreds of drivers had abandoned their vehicles on New York's Long Island, and even snow ploughs were getting stuck. Emergency workers used snowmobiles to try to reach stranded motorists, some of whom spent the night stuck in their cars. Massachusetts, Rhode Island and Connecticut closed roads to all but essential traffic.