Europe's Christmas travel crisis has eased slightly, though there is still substantial disruption at a number of airports.
While Heathrow flights are still subject to delay and cencellation, Germany's Frankfurt airport said schedules are slowly returning to normal after several days of widespread disruption.
About 70 flights have been cancelled on Wednesday out of a daily total of about 1,300, but that is a substantial improvement on the 550 cancellations on Tuesday.
The French government said 15% of flights from Charles de Gaulle airport in Paris will be cancelled on Wednesday because of the wintry weather.
But extremely cold temperatures are continuing to plague parts of Europe, making the full resumption of travel services difficult.
Denmark experienced its coldest night in 29 years into Wednesday as temperatures in Holbaek, 40 miles west of Copenhagen, fell to minus 22.5C.
But Copenhagen's international airport expects a normal day.