This is down to the physical properties of how the contaminant reacts to the pressure from the tire.Ī runway covered in ice is classified as "poor" braking action. You might be surprised to learn that a snow-covered runway could be a preferred option to a water-covered runway. 11 inches as these are the ideal conditions for aquaplaning. These conditions are found when there is water or slush with a depth greater than. More: Pilots love flying to these 5 US cities - here's why Where things do start to change considerably is when the braking action becomes "medium to poor." Even at this stage, the effects on break efficiency on a "medium" runway are fairly minimal. If the OAT is warmer than 5°, compacted snow gives a braking action of "medium." Within the same classification is dry or wet snow deeper than. Despite being called an "ice runway," the reality is that it was more likely to be a "compacted snow" runway. There, specialist equipment cut groves in the runway to improve the contact between the tire and the surface. If the outside air temperature (OAT) is 60° or colder, compacted snow gives a braking action of "good to medium." These are most likely the conditions experienced by the crew of the HiFly A340 which landed in Antarctica. How the depth of deposit affects the braking efficiency. As a result, when the reported depth is greater than that, the likelihood of aquaplaning is increased, resulting in braking actions outside of "good." Scientific research has shown that aquaplaning is unlikely to occur with deposits less than. For a wheel that is used to steer the aircraft, it can also reduce the efficiency of the steering. When this happens, the surface of the tire is lifted away from the runway, reducing the braking efficiency. The problem arises when a contaminant, such as water or snow, builds up between the firm surface of the runway and the tire. When the brakes are applied, this ensures that they operate at their maximum efficiency, slowing the aircraft down. In normal conditions on a dry runway, the correct surface area of a tire is in contact with the ground. 11 inches is considered contaminated and this is down to an effect known as aquaplaning. 11 inches deep, the aircraft will stop just as effectively as if it were just rainwater on the surface.Īny runway with a deposit greater than. This means that a runway can be entirely covered in snow, but so long as it is less than. This includes frost, slush, dry snow and wet snow. 11 inches will give a 'good' braking action. The braking action has six classifications - good, good to medium, medium, medium to poor, poor and nil.įor the most part, any deposit with a depth less than. ![]() Related: How pilots predict bad weather and keep your flights smooth ![]() As a result, the way in which the airports are physically laid out differs from that of airports in most of the world.īy signing up, you will receive newsletters and promotional content and agree to our Terms of Use and acknowledge the data practices in our Privacy Policy. However, farther afield in the likes of Scandinavia and Canada, snow and ice are a daily factor in airport operations throughout most of the winter. In the U.K., this normally only extends as far as de-icing the aircraft on those frosty mornings with only a handful of days in the year where we get heavy snow that grinds airports to a standstill. Winter OperationsĪs the leaves on the trees begin to fall and we have to scrape ice off our cars in the morning, the world of winter aviation operations isn't far away. However, like with all things in commercial aviation, safety is always the number one priority for pilots so there are a number of precautions that are taken to ensure landing in wintery conditions is always safe. After all, we all know how precarious driving a car on icy roads can be so surely landing a 190-ton aircraft on ice is extremely dangerous? In a way, yes it can be.įor more TPG news delivered each morning to your inbox, sign up for our free daily newsletter. The notion of landing an aircraft on ice may seem slightly perplexing. The crew made the 2,500nm journey from Cape Town before touching down several hours later on the specially created nearly 10,000-ft. Last week, an A340 operated by HiFLy became the first four-engine aircraft to land on an ice runway in Antarctica.
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