Flying in the winter 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.

Preflight is one of the important items of safe flight. During winter it becomes even more so, think ice or snow covered runways. Winter adds a whole new dimension to all of this.

Preflight

During this phase the decision 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.

Departure
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.

Enroute
If your flight will take you through hilly or mountaineous terrain then pay special attention on cloud bases (ceilings), temperature dew point spread, visibility, freezing level and if any precipitation is forecast. A frozen up airplane without any protection or one that is not certified for flight into known icing conditions could end up very nasty very soon. Do not forget to request PIREPs from the weather briefer.

Destination and alternate
Check the weather minima 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.

Runway surface
With snow and icing expect the runway to be slippery and braking action poor to none. Directional control can be a problem then especially with taildraggers.

Daylight
During the winter the hours of daylight is at minimum depending on which latitude you are. VFR night flight might not be an option. Daylight will 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 visibility problems.

Cleaning the aircraft
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 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.

Engine starting

With some engines it is recommended to pull the propeller through several times with the ignition off. This will relieve any stress due to oil thickening in the engine and make starting much easier. Only recommended when the aircraft flight manual recommends it (Rotax for example).

Preheating
Engine preheating eases starting by raising the temperature of the engine and oil and reduces warm up time and saving fuel. It can be done in several ways:

• Electric heatings pads attached to the engine sump, this will add to the weight of the aircraft (you could hang a 100 watt light bulb underneath the sump, this burning lamp emittes lots of heat too)
• An electric heater with hoses running to the engine compartment and the cabin
• The use of a heater hanger
• Remove the warm oil after the last flight and keep it inside a warm hanger. Add before the first flight of the next day

Sometimes the battery is preheated as well with a special harness wrapped around the battery and connected to a suitable electrical outlet. With watercooled engines the use of thermostats in coolant and oil system may help to keep the engine running at the correct temperatures.

A winterization kit installed on the engine will help keeping the cylinderhead and oil temperature within limits set by the manufacturer during flight.

Starting an engine can be difficult when temperatures are dropping, it will require more priming (carburetted engines in particular) and therefore increase the change of fire during engine start. Those engines lucky to be equipped with fuel injection and a FADEC should start a whole lot easier in wintertime.

Diesel engine operators should expect to have to glow somewhat longer before starting the engine. FADEC equipped diesels regulate this automatically.