A lot of snow gives beautiful pictures. Not only in nature but also in airports. While everything is done in airports worldwide to keep the runways of aircraft free of snow and ice in winter weather, there are also places where this is not possible or even deliberately not done.
As soon as winter conditions arise, action is often taken to keep the runways clean. At Schiphol, the snow is pushed to the side of the runway with nine snow shovels. Between these vehicles and behind follows a snow thrower that can throw up to 6750 tons of snow per hour over a distance of 35 meters. For comparison: it is the weight of a passenger car per second. Then one last snow plow arrives to sweep away the last remnants of snow.
All in all, it takes about twenty minutes to clean one of the three-four kilometer long tracks. With a 40-meter-wide sprinkler system, an airport sprinkler wagon ensures that a runway does not freeze and become slippery. This is not done with ‘normal’ salt as on the road, but with the fully biodegradable antifreeze liquid potassium formate (KHCO2) to prevent corrosion of the aircraft. Finally, a slip resistance measurement follows. If the grip on the runway proves to be insufficient for a safe landing, the pilot makes an extra turn in the air.
Snowfall causes delays not only on arrival but also on departure, often triggering a domino effect. After all, a delayed flight affects subsequent flights. An airline may also decide to cancel certain flights in advance based on information provided by KMNI. It is obvious that the choice falls on European flights, ie short-haul flights with a destination that is flown several times a day. One can guess that the occupancy rate has been taken into account: if few seats have been reserved, there is a good chance that the flight will be canceled. In such a case, however, the first and last flight of the day remains out of reach.
If the braking distance of an aircraft becomes longer due to slippery conditions, the runways at some airports are on the short side. Examples include: London City Airport (LCY), Florence Amerigo Vespucci (FLR), Grenoble-Isère (GNB) and Chambéry-Savoie (CMF). Difficult, especially when you consider that the latter two are famous winter sports destinations where winter can really turn out well. Elsewhere, in the event of frost, a problem of a completely different nature arises: the lack of facilities for de-icing aircraft. Accident, for example, if you want to depart from Jerez de la Frontera (XRY) airport in southern Spain, and a snowstorm occurs just then. Last winter, Teuge, where planes heavier than six thousand kilograms are not welcome, even had to have people picking up the snow shovel to clear the track.
Red in the snow
Snow, hail or sleet must always be removed before the aircraft takes off. If this does not happen, the airflow around the appliance will be affected by the frozen ice and it is not only unwanted but also dangerous. In a very special way, Air Greenland takes into account the winter conditions that it is more often than not confronted with in the light of its home country. The airline not only got its entire fleet provided with a red color, because it is the main color of the Greenlandic flag. In the unlikely event of a crash, the wreck of a red machine will be easier to find in a snowy landscape.
Smaller aircraft, such as the Havilland Canada DHC-2 Beaver and DHC-3 Otter, can not only be fitted with wheel suspension or floats as standard, but also with skis. This was already the case at Fokker Universal much earlier. The latter was a design by Robert Noorduyn, who later also constructed the Norseman, a rugged workhorse that coped perfectly with the sometimes harsh Canadian climate. The name Norseman is well chosen for this aircraft, due to its meaning: ‘Inhabitant of the Nordic countries.’ In the period 1935 to 1959, no less than 903 copies rolled out of the factory at the Dutch Noorduyn, in the variants Mk.I to Mk.VI. 759 of these were delivered to the United States during World War II.
With sports aircraft, the skis can be ‘tied up’, which can lead to a very special winter coziness.
Skifly-ins for smaller aircraft are arranged in Isny, Ohlstad and Kempten, among other places, when there is sufficient snow. ‘Ski-Fliegern’ or ‘Brettl-Fliegern’ fun takes place in pleasant winter moods. The inner man is well taken care of with hot chocolate, coffee, mulled wine, cake and hot sausage.
Without skis as a base, landing with a sports plane in the snow is a different story. On March 24, 2014, an unplanned pilot took the advertising slogan for the winter sports holiday ‘From the plane fast on the slopes’ very seriously. In Verbier, Switzerland, the unlucky pilot put his plane down in a place where helicopters are parked to take people on heli-ski trips and other recreational activities. Wind problems that prevented the man from landing on the local runway, combined with a possible gas shortage due to the frequent circling, made him choose this place. A helicopter had to be called to lift his plane off the track.
Snow thanks to planes
Aircraft, in turn, can also cause snowfall, researchers at the U.S. National Center for Atmospheric Research have found. In 2007, they flew at an altitude where clouds do not usually cause precipitation. This is because they consist of supercooled water droplets, water that is colder than freezing but still liquid. These drops are too small and light to be pulled to Earth by gravity. Once in contact with an aircraft, especially the ice-cold metal of the wings, the liquid can freeze. In addition, the drops can only remain liquid if they do not move too much. A small disturbance from an aircraft can give rise to the formation of ice crystals, which are necessary to form precipitation.
Scientists looked at the images from the Earth’s radar after their flight. For example, they saw that exactly in the wake of their flight, there was an empty snow in an elongated area. The snowflakes formed in this way are flatter and have less structure. Nearly eight percent of the clouds consist of supercooled water droplets. The clouds in Western Europe are about two to six percent of the time ideal for being emptied by planes taking off or landing. At such a moment, a hole can appear in the clouds, a so-called flying or pilot hole.