Grounded
Aircraft are seen on the snow-covered tarmac at Heathrow Airport, in London, on Monday Dec. 20, 2010. Snow and freezing temperatures continued to cause holiday travel chaos for road, rail and air passengers in Britain and much of Europe Monday, raising fears that many will not get home in time for Christmas. No more than a third of flights from Heathrow will operate until Wednesday morning.

• Frozen Britain: Snow and Ice Cause Chaos
• Heavy Snowfall Cripples London