The UK government has stepped in to help Heathrow Airport as hundreds of thousands of passengers are affected by severe weather conditions.
Hundreds of international flights have been unable to land or takeoff at the airport, causing flight schedule chaos worldwide.
The airport announced it had reached an agreement with the government to allow flights to take off throughout the night as weather conditions permitted.
Heathrow currently has only one of its runways operating, handling a limited number of arrivals and departures -- primarily flights that had been previously diverted to other airports, and to allow movements of flight crew to allow airlines to get flights operating from other airports.
Heathrow has been unable to cope with the weather conditions despite extensive facilities and ground staff allocated to clearing snow and ice. A spokesperson said once the crisis was over, the airport board would "reflect carefully on the lessons we can learn and the steps we need to take to better prepare for these periods of poor weather."
A maximum of one third of scheduled flights will operate at Heathrow until at least 6am on 22nd December (5pm on 22nd December, Sydney time.)
"Passengers should anticipate further delays and cancellations in the following days and potentially beyond Christmas Day," the airport said in a statement. "Passengers should not travel to Heathrow without a reconfirmed booking. If passengers can travel at another time then they should do so."
Airlines are currently updating which flights have been cancelled and www.heathrowairport.com is showing the latest available flight information. If the website shows 'contact airline', then the flight will not be operating as scheduled, according to the airport.
Heathrow Airport was closed over the weekend following a 12.7cm snow fall in around one hour on Saturday. There have been subsequent swings in temperature to the extent that ice built up around the aircraft parked on the ground, according to the airport.
"Heathrow is currently using every available member of staff and several hundred additional contractors have been brought in to clear the situation. BAA has also deployed additional staff to provide comfort to passengers in its terminals," the statement concluded.