Despite global temperatures continuing to rise on average, winters appear to be getting colder around the world. In November 2010, for example, the UK experienced record lows, while the same was also true of the USA. Furio Rossi, Sales Manager at Fresia of Italy, which supplies a wide range of snow removal equipment, adds that the winter weather of 2009/2010 and 2008/09 was unusually severe, with airports closed across Europe.
Meanwhile, Tom Carle, Sales Support Manager at the Oshkosh Corporation, which supplies a wide range of snow clearance vehicles and equipment to the US explains that the winter weather on the other side of the Atlantic has also been unusually severe. "Many parts of the US have experienced significant increases in their overall snowfall during the past few winters, which have had a significant impact on airports."
The same is true of Sweden according to Magnus Lindner, who heads up the training division for the snow clearing team at Stockholm-Arlanda Airport. He says that after a hard winter last year the snow has arrived much earlier than usual this year.
One of the main problems facing airports is ensuring that runways remain ice free. Mr Lindner says that apart from the dangers that an aircraft can skid off the runways while taxiing, ice is very dangerous for aircraft landing at an airport; "It takes much longer for them to slowdown because of the lack of friction and this can mean the runway simply isn't long enough. That's why we don't want ice forming on the runways."
Braving the cold
Indeed, icy runways are one of the main reasons that airports have to close in snowy weather. The key to preventing ice is snow clearance, according to Mr Lindner.
Indeed, snowploughs and snow blowers are the first line of defence against ice and snow build up. Next, many airports use a runway sweeper, a rotary brush with steel bristles that removes snow and ice by abrasion.
The sheer volume of snow that has to be removed can be extraordinary. More than 1,300t of snow was removed from the runways at Southampton Airport, for example, on one day in December 2010.
Specialist teams also go out and check conditions frequently during snowy weather – sometimes as often every 15 minutes - and the teams have specialist equipment on board to check how much grip is available.
Snow clearance is relatively easy if it is dry snow, but once the snow starts to melt and then refreeze problems emerge. Potassium based runway de-icers are used around the world, but they are basically salts that will melt ice and pose a hazard to aircraft as they can cause corrosion.
Cryotech Deicing Technology, a division of General Atomics International Services Corporation, a San Diego based company specialising in energy-related research and product development, for example, markets environmentally compatible acetate-based highway, commercial and airport runway de-icers.
If the de-icing fluid is not washed away by rain or snow, it can keep the surfaces free of ice for up to 24 hours. About half of the de-icing liquid can be recovered with specialist vehicles which suck it up again.
Stockholm Airport uses snow clearance vehicles and de-icers to prevent ice. It also has a secret weapon in the form of an underground aquifer that can be used to pump hot water under the apron although it is not piped under the runways.
But Mr Lindner does not believe that heating systems under runways are necessarily the answer. "They tend to be turned on too late – since they take a couple of days to heat up the runways the snow will already have landed."
Aircraft can also help, particularly at busy airports such as Heathrow because if a runway has a plane landing or taking off every couple of minutes, the heat from the engines helps to keep the surfaces clear.
The element of surprise
The main problem for many airports is the element of surprise, as winter can strike heavily and unexpectedly in many countries. It is therefore vital to prepare a rapid response plan.
Weather and ground temperature sensors near airport runways, together with data from local meteorological offices can help the airport to predict if snow is likely to arrive but usually the data is only good for forecasting what will happen over the next few hours rather than days.
For rapid response to work, operators must be aware of a number problems to deal with, such as refuelling the snow thrower fleet, running out of de-icing fluid, bridges freezing fast and aircraft encountering technical problems after de-icing.
Airports, such as Schipol in Amsterdam regularly conduct training exercises to deal with these scenarios. In reality if the weather gets rough enough the best and only scenario is to shut down shop.
Hopefully the European 2010/2011 season won't be one to forget for travellers and airport staff alike.