Winter Operations
Although colder air means there's less danger of exceeding temperature limits, there are hazards, too, including freezing precipitation, low ceilings and cold temperatures. Rapid changes in these are typical, and it’s possible to get weathered in for days at a time, so don’t forget your chocolate bars (you need lots more calories).
The Weather
In the Frozen North, the best conditions are in late winter or early spring, with one of the major problems being darkness. Once the snow is down, the air is quite dry and it can stay clear and cold for long periods, so you can usually ignore fog and the rest until it gets a bit warmer.
Above the 60th parallel, don’t expect the weather to behave rationally at all. For example, further South, the East wind is responsible for bad flying conditions, but up there the West wind is the culprit, as well as large swings between low and high pressure which will often bear no relation to what the weather is doing (so don’t rely on cloud shadows over the ground as an indicator of surface wind speed). Aside from barometric changes, look out for wind shifts, which will bring changes in wind speed and amounts of blowing snow and less visibility – even a difference of 100 feet in elevation can mean the difference between snow or not. Temperature changes often mean bad weather is approaching from the North – if it drops, expect ice crystal fog, which is the low level equivalent of contrails made at high altitude, and created by air disturbance, which could actually be from the aircraft itself. Rising temperatures will produce melting and poor visibility. The chill factor from rotors can reduce the ambient temperature by several degrees.
When it gets to below -20 or so, contact gloves will prevent your skin freezing when it comes in contact with cold metal, which is a more efficient conductor of heat than air is. You may also need sunglasses. Always dress properly—in a forced landing it could be that the clothes you wear will be the only protection you have. Also, being cold when you are actually flying is a Flight Safety hazard – metal foot pedals will conduct heat away from your boots very quickly. Extra time for planning should always be allowed and the pre-flight inspection should include you—being improperly dressed and making a series of short exposures will fatigue you more quickly, especially when the clothes you are wearing are bulky and awkward to move in. Maintain blood sugar levels as more calories are consumed in the cold (you need 3000 calories a day in Norway). If the air is very dry (like in the Arctic), you will lose fluids more quickly through the usual ways, but especially breathing. Losing 10% causes cause delirium, and a 20% loss is fatal. You could try and eat snow, but the conversion to water takes more energy, so melt it first.