Why are UK airports so poor at dealing with snow?

Stockholm-Arlanda, Sweden’s largest airport, has never once shut because of snow.

Serving one of the coldest capitals in Europe, the airport prides itself on how it combats adverse weather, employing one of the most efficient winter operations in the business.

It might suffer occasional delays, close one of its three runways, or restrict flights to only arrivals, but it has never shut its doors altogether.

British airports, on the other hand, tend to grind to a complete halt in the face of much tamer conditions.

Closures aside, even the lightest flurries of snow seem to cause cancellations and delays at the UK’s largest hubs. On Monday, British Airways cancelled 36 flights from Heathrow first thing, while in December flights were grounded on two separate occasions when snow arrived across the country. There are concerns more snow this week will cause further disruption.

Why does snow cause delays?

“If aircraft runways, taxiways and aprons are contaminated with snow and ice then that needs to be cleared, which takes time, and in turn reduces airfield capacity,” explained Paul Beauchamp from Nats, the UK’s air traffic control provider.

“Add to that the potential for low visibility and the whole operation has to slow down to keep [the airport] safe.

“Depending on the severity [of the weather], it might also be necessary for us to work with the airlines and airports to agree what are called ‘flow regulations’ to reduce the number of flights arriving into the airspace, again in order to maintain safe and manageable traffic levels and not to exceed what the airport has capacity for on the ground.”

Too hot? Too windy? Too wet? How planes fly in extreme weather

Such a ‘flow regulation’ was imposed on Heathrow in December when the capital saw snow, leading to delays and cancellations.

When an airport is running at high capacity - as Heathrow does - with a packed schedule of flights, even the smallest disruption can have vast knock-on effects. In anticipation, some airlines will cancel flights in advance to provide some slack in their operations.

A British Airways statement, for example, said of this week’s disruption that it had “proactively cancelled some services”.

Author and pilot Patrick Smith says that delays caused by snow are no different to the way poor weather might affect a normal commute.

“Bad weather causes delays in two ways,” he says. “The first is materially - the physical slowdown that inevitably results when human beings are forced to perform their duties in harsher than normal conditions.

“If it’s raining or snowing, planes tend to be late taking off for the same reason people tend to be late getting to work or school: we and our vehicles move more slowly; simple tasks take longer.

“The second way, which has greater repercussions and is harder to predict, is by blocking up the air traffic control system. ‘Weather delays’ is frequently a misnomer. More correctly, it’s a traffic delay - the product of aircraft saturation at departure point, destination or someplace in between.

“Even in ideal weather the skies are crowded and delays common; throw in ice, snow, low runway visibility, strong crosswinds, slick surfaces and so on, and you’ve substantially reduced the number of allowable arrivals and departures per hour.”

At a glance | UK snow facts

In February 2012, when Heathrow, then operating at 99.2 per cent capacity, was struggling to cope with the weather, the west London airport cut 30 per cent of its flights in anticipation of freezing fog, but before a snowflake had fallen.

A spokesperson said at the time: “If we had the same conditions again we would probably take the same pre-emptive action and cancel 30 per cent of our flights.

“Given that we are running at more than 99 per cent capacity it is the only way to get slack in the system.”

Are UK airports prepared for snow?

“We don’t really stop preparing and planning for winter operations,” says James-Paul Straiton, Glasgow Airport’s airfield operations manager, speaking to Low Cost and Regional magazine.

“As soon as one winter has passed we hold a wash-up learning event to take on board from the previous season.

“It’s not like you can set your watch for snowfall in the same way you might in other countries when winter sets in.”

Straiton confirms the theory that because the UK experiences so little snow it does not have the expertise to know how to deal with it as efficiently as an airport in, say, Sweden.

“We don’t see enough snow to be able to be experts in how we operate, clear or manage it.”

So every snowstorm for UK airports is a lesson.

He also says that while more wintry countries might receive dry snow, the snow in Britain can often be wet and turn to slush and ice quickly, making it more difficult to clear.

Airports more likely to deal with extreme weather conditions on a regular basis are also likely to invest more heavily in their equipment.

Following the 2012 disruption, then-prime minister David Cameron’s spokesperson admitted that British airports “have to make judgements about how much money to invest in [weather] mitigation”.

Why are the Scandinavians so good at it?

“At Arlanda, we use about a hundred different vehicles just for snow-clearing purposes,” Stockholm’s chief of airside operations Christian Nyberg told Airport Technology.

“On the runways and taxiways, the [ploughing, sweeping and blowing vehicles (PSBs)] are used, followed by anti-skid spreaders, snow blowers and friction test cars. At the apron area/stands we use front wheeled loaders in different sizes. It quickly gets heavy, since the line of snow left behind by the PSB machines can weigh about 120 kilos per metre, so Stockholm Arlanda Airport’s snow throwers have high capacity – they handle 7,000 to 8,000 tonnes of snow per hour.

"If we didn’t have the right equipment needed to perform this it would be like fishing without a hook.”

Glasgow, on the other hand, operates five Overaaseb RS400 runway-clearers, and three SB 90s.

At Oslo airport in Norway, the operations team has in its arsenal, a 4-tonne TV-2000, the world’s largest ploughing vehicle, which can move 10,000 tonnes of snow in under an hour.

Is it just the UK that suffers?

This morning a number of airports around Europe were suffering from weather-related delays including Brussels, Rome, Zurich, and even Stockholm.