Heavy snow and ice grounded air travel across Europe for a third day on Monday leaving thousands of passengers stranded even as airports struggled to clear a backlog of flights cancelled or delayed by snowfalls.

The world’s busiest international airport, London’s Heathrow, operated a limited schedule on Monday as one of its two runways was open and advised passengers not to travel to the airport unless their flight is confirmed.

Airport operator BAA Airports Ltd said airlines worked to move aircraft and crew back to their normal positions as severe winter weather continued to cause disruption.

Heathrow said delays are expected for next several days as more snow is forecast for England and Germany.

About 15 centimeters of snowfall forced cancellation of flights at Heathrow and Gatwick on Sunday. The Met office has forecast as much as 20 centimeters of snowfall on Monday in parts of south and west UK. World Meteorological Organization said Frankfurt will likely have ‘light snow’ Monday and Tuesday.

Icy conditions also curtailed Europe's train services, left cars skidding through slushy streets and saw major events postponed, including music shows and sporting events.

British Airways cancelled 70 of its 130 departures and 89 of its 133 arrivals on Monday.

Customers whose travel is not essential are encouraged to cancel their flight, in return for a full refund, or to consider changing their flight to another date over the next 12 months, it said.

London Gatwick said the airport's sole runway is open Monday and operations are returning to normal. Virgin Atlantic said it was working hard to re-establish its flight schedule, but a number of its aircraft were out of position due to the weather conditions and it would be 24 to 48 hours before schedules were completely back to normal.

Gatwick canceled six flights and was expecting freezing fog to mid-morning with snow flurries on Monday afternoon.

However, Virgin Atlantic plans to operate its full schedule of flights from Gatwick airport, albeit with some delays, although there would be severe disruption to its Heathrow flights.

Stansted Airport's website showed flights were running with delays averaging around an hour.

Deutsche Lufthansa AG expects a reduction in flights within Germany and Europe, with much disruption at its Frankfurt hub.

Flights at Paris’s Roissy-Charles de Gaulle Airport were reduced by 40 percent due to snowfall in northern France on Sunday, the nation’s civil aviation authority said. French authorities have prevented heavy trucks and coaches from using roads in Northern France and the greater Paris area and car use is inadvisable.

French airport operator Aeroports de Paris said severe delays and disruptions were being experienced at Paris's Roissy-Charles de Gaulle and Orly airports. It said it didn't expect any flights to land at Orly before Monday afternoon.

Air France-KLM said passengers departing from or arriving in Paris should expect major delays all day. Snow was still falling in Paris Monday morning and the city's public-transport operator RATP said about 40 out of 50 bus lines were suspended.

Eurostar Group Ltd.’s trains and crew are “out of position” due to the weather and services will probably run with speed restrictions and delays. Eurostar expects to run reduced services for “a number of days”.

Eurostar’s high-speed rail services connecting London, Paris and Brussels were severely hit and it was operating a contingency timetable.

In Frankfurt, about 300 flights were cancelled on Monday even as the airport said many flights were operating but with considerable delays.

Amsterdam’s Schiphol Airport said it was open and some flights had been canceled.

London Underground trains were packed with dejected holiday travelers in search of hotel rooms, while many tourists complained there was little clear information amid the chaotic scenes at the city's airports.

British travel-industry group ABTA expects cancellations and delays to continue through this week, potentially causing further disruption for many Christmas travelers.
Inevitably there is always some knock-on effect when there's a situation like this. People will need to consult with their airlines next week to check on their flights, said ABTA spokesman Sean Tipton.
However, he said the disruption caused by Europe's blast of icy weather was minor compared with the chaos triggered by the giant ash cloud spewed from Iceland's Eyjafjallajokull volcano earlier this year.

Cathay Pacific Airways Ltd. canceled two Hong Kong-London flights Monday and the airline expects to operate two other services on the route and all four of its flights from London.

Air New Zealand Ltd. said London flights may terminate at the midpoints of Hong Kong and Los Angeles if weather conditions didn’t improve.

Qantas Airways Ltd. has 3,000 passengers affected by the shutdown, after it canceled flights from London and turned back other flights headed to the U.K. About 1,000 passengers are stranded in London and the rest across Asian hub.

First Capital Connect trains have delays of up to 40 minutes on some trains into central London, according to National Rail Enquiries’ website. London Midland services on all routes are subject to delay and cancellation, while Southern trains is operating a normal service Monday.