Flying during the winter season can be one of the most spectacular experiences there is. Especially in the mountains. But winter time means that we have to take special preparations to safeguard ourselves and the aircraft, so that flying remains fun even in the cold season and does not become a life threatening situation.
Performing a thorough preflight is one of the important items before the flight. During winter it becomes even more so, think ice or snow covered runways. As you can see winter adds a whole new dimension to all of this.
During this phase the decision to go or no-go is taken. During winter the weather briefing is very important and the briefing should concentrate on three items: departure, enroute and destination weather.
Take a look outside and ask yourself the question: is this the weather that I would want to return to if I needed to do that? What about an alternative airport if you needed to return home for some reason? Marginal winter weather has taken too many lives, play it safe and use higher weather limits in winter time than you would normally do in summer.
If your flight will take you through hilly or mountainous terrain then pay special attention on cloud bases (ceilings), temperature dew point spread, visibility, freezing level and if any precipitation is forecast for the area. Flying with a frozen up airplane without any de-ice or anti-ice protection or one that is not certified for flight into known icing conditions could end up very nasty, very quick. Do not forget to request PIREPs from the weather briefer.
Check the weather minimums for your destination, with attention to visibility and try to figure out if there is a trend like visibility going down the last couple of hours. Due to lower temperatures in winter time fog will be more common, even more so when a high pressure area is present. If the airport is situated lower than surrounding terrain, expect cold air to flow to the airport possibly reducing visibility in early evening.
With snow and icing, expect the runway to be slippery and braking action to be poor to none. Directional control can be a problem then, especially so with tail draggers and a bit of crosswind.
During the winter the hours of daylight are very low, depending on which latitude you are. A VFR night flight might not be an option at all. Daylight will even be shorter under a broken or overcast cloud ceiling. And as the sun sits at a lower azimuth in the sky, landing or flying headings towards the sun can create serious visibility problems.
In short: the aircraft should be clear of any snow or ice. Any frost is very unpredictable in its effect on aerodynamic properties of the aircraft wings and must be removed. Be careful when cleaning the aircraft as not to damage its surfaces. Pitot static systems should be free and clear of any ice or dirt, check if the heater element is operating in the pitot tube during pre-flight walk around.