12 December 2016 / 0 Comments
Ice on planes: Do passenger jets need winter tyres?
Estonia’s main airport upgrades to cope with increasingly extreme weather —and counter the environmental effect of all the de-icing it has to do
Tallinn gets about a half metre of snow each month in winter. Its record low temperature is -32.2C. Climate change makes the weather in the Estonian capital, which is on the same latitude as St. Petersburg and Stockholm, increasingly unpredictable. This year the snow started early. “We’re not easily surprised here at Tallinn Airport. But snow already in October? That was a surprise,” muses Einari Bambus, the airport’s operations director. By the beginning of this December tons of snow had been moved to dumps near the runways. Often it’s still melting in midsummer.
So when you’re waiting for take-off at the Estonian capital’s airport, you might be wondering: do airplanes need winter tyres?
Sugar and salt and everything anti-ice
“People tend to think the colder it gets, the more de-icing and de-snowing we have to do. That is not the case,” explains Bambus, who’s also a member of the board of Tallinn Airport. “The most critical weather for aircraft is actually when there is a lot of humidity, and the temperature is just below freezing point, between 0 and -5C.”
Such conditions are commonplace in the seaside city of Tallinn. It requires the airport to use a lot of chemicals to fight the sleet and the snow. Upgrading the drainage network to catch the chemicals in the de-icing pellets and liquids, creating a new snow dump area, and replacing the airside lighting system with LED lights that don’t heat up - and thus cause more ice to form on the runway – are all parts of the EUR 80 million upgrade project that the airport is currently undergoing. The European Investment Bank has loaned EUR 30 million toward this upgrade. That’s backed by the European Fund for Strategic Investments, which the Bank operates with its own funds and an EU budget guarantee as part of the Investment Plan for Europe.
While salt products have traditionally been used to de-ice roads and pavements, salt corrodes aeroplanes. Instead, surprisingly, sugar-based liquids – or rather by-products of sugar beet processing – are used to spray aircraft before take-off, so that the moving parts don’t freeze when the plane suddenly ascends into even lower-temperature air.
And they don’t need to scrape their windows either!
We might get by with a couple of litres of anti-freezing windshield wiper liquid in our cars all winter – in addition to the quickly accumulating hours those of us without garages spend scraping the ice each morning. But it can easily take 300 litres of de-icing solution to cover a plane just once.
After that - it’s a race against time.
The de-icing liquid works by lowering the freezing point of water. Depending on the amount used, it only works for 10-15 minutes. At Tallinn Airport, if the wind is blowing from the west, it may easily be 5-7 minutes until the plane reaches the beginning of the runway. If another aircraft arriving late and delays take-off, the ice situation gets critical. Then the plane has to be sprayed again. It’s an expensive process—with an environmental impact.
This is why the airport’s planned improvements also include the capacity to do the de-icing right before the runway, not just at the gate.
“It is key that a Nordic airport like Tallinn applies the best available technology to collect and treat the majority of aircraft deicing fluids used,” says Elena Campelo, EIB air, maritime and innovative transport division engineer. “By doing this, they will ensure adequate groundwater protection against the infiltration of melting snow and de-icing products, and make possible the treatment and monitoring of that water.”
Other investments include reconstruction of the existing runway, an extension of the passenger terminal, and the renewal of fire and rescue equipment.
The project aims to improve environmental and safety performance, alleviating congestion at the main gateway to Estonia, and accommodating future growth in traffic. It will be able to handle 3.4 million passengers each year, up from the current 2.2 million, says Thomas Schmidt, EIB’s loan officer for Estonia.
More passengers usually means more planes. So the airport must make sure it can clear snow and de-ice as efficiently as possible, and in line with environmental considerations, to keep planes continuously taking off and landing.