Drivers were heading off on the big Christmas getaway today as the freezing weather kept its grip on the country.
With many areas waking up to yet another icy morning, motorists heading home and out shopping faced one of the busiest driving days of the year.
The number of cars on the roads was expected to peak later this evening as people try and get home before Christmas Eve and out for some last-minute bargains.
The AA's Paul Watters said: "We are building up for a problematic day on the roads."
Passenger backlogs at airports and on the trains have begun to ease, but critics are rounding on the UK's inability to cope with wintry weather.
Much of the country saw temperatures fall below zero overnight, prompting widespread warnings for icy roads.
The majority of the UK should stay dry but cold today, with slight snow showers in northern and eastern parts of the country.
Weather-related troubles saw the motoring rescuers field an estimated
21,000 call-outs yesterday, and Mr Watters said: "We don't expect today to be any easier."
Heathrow - which has made headlines for days as massive amounts of flights were cancelled due to snow and ice - said it was expecting to operate 1,206 flights today, almost a full schedule.
After reopening its second runway on Tuesday, the gateway fulfilled two-thirds of its business yesterday but stressed passengers should not expect an immediate return to normality.
Mayor of London Boris Johnson said operator BAA had "very serious lessons" to learn from the chaos.
BMI chief executive Wolfgang Prock-Schauer also claimed the airport "did not have enough de-icing fluid" - something a Heathrow spokesman strenuously denied.
"It is categorically untrue that we have either run out of de-icer, failed to order enough de-icer or accepted de-icer supplies from the Government," the spokesman said.
Meanwhile under-fire BAA chief executive Colin Matthews announced he would forgo his annual bonus.
Mr Matthews said: "I have decided to give up my bonus for the current year. My focus is on keeping people moving and rebuilding confidence in Heathrow."
BAA would not reveal how much his bonus was.
And after cancelling more than 2,000 flights, British Airways said it hoped today and Christmas Eve would see it operate a full long-haul departure schedule from Heathrow. It will also operate a normal schedule at Gatwick and London City airports.
All airports continued to tell customers to check with their airline if their flight was operating.
Sean Tipton of the Association of British Travel Agents said: "The travel industry is very pleased that both Heathrow and Gatwick are returning to normal service.
"However, there will still be some delays and cancellations due to the many aircraft being out of position.
"Many package holidaymakers whose flights were cancelled over the weekend will now be jetting off on holiday due to their flights being rescheduled."
After the Eurostar was crippled, a company spokesman said it was running 90% of its service.
The travel improvement coincided with weather forecasters predicting relatively mild weather in the run up to Christmas Day.