UK flights are returning to normal after dense fog caused days of disruption for thousands of travellers.
BA expects all its service to return to normal on Sunday
British Airways, which had the largest number of cancellations, has apologised for its delays, and drafted in extra staff to clear the passenger backlog.
It said it was hoping to resume a full schedule. BMI, Ryanair and Easyjet were among the other airlines affected.
Airport operator BAA has asked people not to arrive too early at airports as this increases congestion in terminals.
At the height of the chaos, thousands of passengers were forced to wait for news of flights in temporary marquees outside Heathrow in freezing temperatures.
BA has used larger planes on many European routes to transport more passengers and clear the backlog, while about 4,000 travellers have been taken to their destinations in coaches laid on by the company.
Meanwhile, thousands of train passengers will have to find alternative ways of travelling across the Midlands because of a 24-hour strike.
The action by conductors on Central Trains, which is about holiday pay and working arrangements, means there will be no services throughout Christmas Eve.
The company said it hoped to provide a reduced service on two other days involving industrial action - New Year's Eve and New Year's Day.
BBC transport correspondent Andrew Winstanley said some travellers had "panic travelled" during the disruption and arrived five or six hours ahead of their flights at Heathrow.
Mark Bullock, BAA Heathrow managing director, said the volume of traffic at the airport on Christmas Eve was expected to be around 30% less than Saturday, which is traditionally its third busiest day of the year.
British Airways customers should contact 0800 727 800
or check the www.britishairways.com
website to see if their flight is still operating
There is regular travel information on BBC News 24, BBC Radio Five Live and the BBC's local radio and regional TV news.
This website will have updated advice and there are links to the BBC's travel and weather web sites below.
Operator BAA said out of a daily total of 1,300 flights from its airports on Saturday, 74 domestic and short-haul flights were cancelled.
This compared with 284 cancellations on Friday and 350 on Thursday.
More than 1,000 flights have been cancelled around the UK over recent days.
Worst affected was Heathrow, where air traffic control placed restrictions on flights landing and taking off because of the low visibility in the fog.
BA said at least 6,000 passengers at Heathrow had been affected by disruption on Friday. The airline put on 30 replacement buses to destinations in the UK and northern Europe.
Mr Bullock said on Saturday that the biggest problem airport staff now faced was passengers turning up too early for flights.
Meanwhile, in Manchester passengers on a Monarch Santa Special flight from Lapland staged a sit-in after refusing to continue the journey to Gatwick by bus.
The passengers eventually continued their journey on another aircraft.
A Monarch spokeswoman said: "Due to a technical problem with another aircraft in the Monarch fleet, the decision was taken to keep the aircraft from Ivalo at Manchester, in order to fly a service from Manchester to Alicante that was already delayed.
"Some passengers protested and refused to leave the plane. We were able to offer them a later flight to Gatwick because the aircraft that had originally developed a technical fault came back into service.
"It was not a question of us caving in to the protesting passengers."
BBC weather forecaster John Hammond said on Saturday the fog had finally lifted from Heathrow as well as the country's other major airports, adding that the weather was "back to normal".
"Conditions generally are very cloudy and misty but nothing untoward," he said.
"This is set to prevail over the next two or three days, meaning a grey Christmas, not a white one."