The disruptions to airlines and high-speed trains in continental Europe, and linking Britain to the continent, created travel chaos for tens of thousands of travelers in the busy Christmas period following heavy weekend snowfalls.
They also brought calls for legislation to force airports to deal more effectively with snow and other bad weather.
European Union transport chief Siim Kallas said he was considering forcing airports to provide a minimum level of infrastructure support during severe weather.
London's Heathrow, the world's busiest international airport, and Frankfurt Airport, the biggest on the continent, said on their websites that operations were returning to normal after severe disruptions.
Wolfgang Prock-Schauer, chief executive of airline BMI, owned by Lufthansa, accused BAA of being unprepared for the heavy snow at Heathrow.
"What is really incredible is that 10 cm (4 ins) of snow closed the airport down for two days and then it operated at one-third capacity," he told the Times newspaper.
"BAA was not prepared. It did not have enough de-icing fluid."
A spokesman for BAA, which is owned by Spain's Ferrovial, denied there had been a de-icer issue at Heathrow and said lessons would be learnt.
But he added: "This was unprecedented weather which closed most of northern Europe's airports."
Heathrow was scheduled to operate 70 percent of a normal day's service, about 800 flights, but it was still advising passengers not to come to Heathrow unless they had confirmed flights, the spokesman said.
"We're hoping by the end of the day we'll be up to full operation," he said.
Heathrow reopened its second runway on Tuesday, offering a ray of hope for thousands of passengers stranded in departure halls, some for days in scenes that British newspapers said resembled refugee camps.
"Airlines are currently operating a significantly reduced schedule while they move diverted aircraft and crew back into position," BAA said on its website.
British Airways said that, in line with a directive from BAA, it would operate only a third of its normal flight schedule at Heathrow until 6 a.m. on Thursday.
"It will take some time to rebuild an operation of our size and complexity at our hub airport, Heathrow," the airline said on its website.
"We ask you not to travel to the airport unless you have a confirmed booking on one of the flights that is operating."
Frankfurt international airport was open and running at full capacity on Wednesday after heavy snow shut it down on Monday for several hours and 400 flights were canceled.
An airport spokesman said there was a backlog of about 3,500 stranded passengers, including some 600 who spent the night on emergency cots at the airport.
"The airport operation is getting back to normal," airport spokesman Thomas Uber said . "But it will take a while to catch up."
German rail operator Deutsche Bahn said it would add extra train services from Wednesday to cope with a surge in demand due to air travel disruptions. Deutsche Bahn board member Berthold Huber said the added service would stay in place until December 31.
Eurostar, operator of the high-speed train between London and Brussels and Paris, said it would resume normal check-in service, but asked passengers not to show up until an hour before departure "to avoid congestion and an unnecessary wait."
On Tuesday, thousands of people were forced to queue in frigid temperatures for hours around St. Pancras station in north London as every available Eurostar seat was snapped up by travelers bounced from airlines.
Eurostar said nine of its 52 trains would be canceled on Wednesday but that passengers for those services would be "reallocated onto one of the next available trains."
Although the logjam of travelers was starting to ease, many passengers were irate.
"This was our holiday of a lifetime," a man at Heathrow who'd been planning to travel with his wife told Sky News. "And it's a nightmare."