British Airways domestic flights have resumed at Heathrow after being cancelled since Wednesday due to fog.
Domestic flights restarted on Saturday afternoon
The first flight to take off following the suspension left at 1322 GMT, bound for Newcastle.
More than 1,000 flights have been cancelled in recent days, and other airports in the UK have been affected.
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 were eventually transferred to another aircraft and continued their journey by air.
The flight had left Ivalo, Lapland, at 1.22pm GMT and arrived in Manchester at 4.50pm.
A Monarch spokeswoman said another flight was arranged from Manchester to Gatwick.
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.
She 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."
BA said 55 flights to and from Heathrow, including 10 domestic flights, were scrapped on Saturday morning but that it hoped to run a full service on Sunday.
The airline still used 30 buses to get people around the country and a number of domestic flights operated by other airlines also took off from Heathrow.
Mark Bullock, managing director of Heathrow, told BBC News 24 that normal service would be resumed by the end of Sunday.
He said the biggest problem airport staff now faced was passengers turning up early for their flights.
"If I could offer some advice, it would be to passengers: please check with your airline before departing for the airport, to check that your flight is still going. And please, do not turn up early."
BA flights from Heathrow to Paris and Brussels will resume on Sunday.
The flight cancellations came about after air traffic control placed restrictions on flights landing and taking off at Heathrow, because of the low visibility.
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."
In the run-up to the festive holiday, the Highways Agency has suspended more than half of its 83 roadworks, and many rail engineering works are also being delayed until Christmas.
On the roads
RAC spokesman Adam Cracknell said major problems were not expected on the roads over the weekend.
"We expect there to be about 9 million or 10 million cars on the road on both Saturday and Sunday, mostly between 10am and 4pm as people carry out last-minute Christmas shopping," he said.
"There may be problems in city centres with parking but otherwise we are over the worst of the Christmas traffic."
At Gatwick Airport, where many tourist and ski holiday travellers are expected, there are no reported cancellations and most flights are leaving on time, although there may be some delays.