Winter Pre-Flight Tips

by Justin Hetland
WisDOT Bureau of Aeronautics

The beginning of the winter season came in fast and cold this year, bringing back memories of the not so fondly remembered 2013-2014 winter when we were all introduced to the term “Polar Vortex.” I, for one, hope we won’t have a repeat of last year’s harsh conditions. Now that we’re in the thick of the winter flying season, here are some ways to prepare yourself and your airplane for a cold weather flight.

Aircraft Preparation

It’s easy to rush through your preflight when it’s cold; however, this is the time of year when you should do your most thorough preflight inspection. Be sure to check your manufacturer’s cold weather recommendations and operating guidelines.

Aircraft Parking: Regardless of whether or not you have a climate controlled hangar, it’s always better to keep your aircraft tucked away inside. Parking inside a climate controlled hangar can help prevent condensation from forming in fuel tanks. However, if you don’t have access to a hangar, park your airplane facing the sun. Especially in the morning, sunshine on the airplane will melt frost off the airframe and windscreen.

Cover Important Surfaces: You’ve heard of covering plants to protect them from frost. You can do the same thing to wings and other surfaces on your aircraft to prevent frost buildup. Frost reduces lift by a surprising amount and greatly increases takeoff distance. Also, remember to cover vents, engine inlets/intakes, pitot tubes and static ports.

Clear Off Snow & Ice: When I flew corporate, sometimes we would be in Aspen for a week at a time during snow season, and a hangar was not an option. As a result, we would have to sweep off the snow and ice. This is a must if you find your airplane covered in snow and ice.

Fuel Contamination: Checking your fuel for contamination is important any time of the year, but even more so in cold conditions with large temperature fluctuations. Be sure to thoroughly sump fuel before a flight. As mentioned earlier, parking in a climate controlled hangar will help minimize condensation in fuel tanks. If parking indoors is not an option, try to fill up your tanks as soon as practical after landing.

Fuel Vents: Make sure fuel vents are not plugged with ice or other frozen materials.

Baffles: Baffles help restrict large amounts of cold air from entering the engine compartment and may be recommended below certain temperatures by the manufacturer. At times, FAA approval is required prior to installation. On aircraft that experience wide temperature variations during operation, it’s also recommended that you closely monitor cylinder head temperatures if possible.

Oil: Winter flying often means changing to a different weight oil. Check with the manufacturer for recommendations on what oil to use at low temperatures.

Oil Breather Tube: Due to the nature and location of the oil breather tube on some aircraft, it should be carefully checked during preflight to make sure condensation has not frozen in the tube. A frozen oil breather tube can lead to engine failure in flight due to pressure build up in the crank case causing a seal to rupture or the oil filler cap to blow off, resulting in loss of oil pressure.

Propellers: In cold weather, oil, like a lot of fluids, becomes thicker and can congeal in propeller governors, which can lead to prop control difficulties. During training in multi-engine aircraft, feathering should be used with caution to not let the engine sit for an extended period as oil could cool enough to cause difficulty re-starting.

Cabin Heat: If you plan on warming yourself and passengers with a muffler shroud type heater, have a carbon monoxide detector in the cockpit. Also, consider a thorough inspection of the exhaust system to check for cracks that can leak CO into the cockpit.

Wheel Wells & Wheel Pants: These are great places for snow and ice to accumulate while taxiing. Consider removing wheel pants in slushy conditions when the slush could re-freeze in flight causing wheel and brake issues during landing. For retractable gear aircraft, the best thing to do is avoid slush and mud in cold conditions as recycling the gear shortly after takeoff is not recommended unless it’s an emergency situation.

Personal Preparation

Knowing you have to preflight your airplane outside in the cold can help you decide what to wear on a winter flying trip. One should not hurry through the preflight just because it’s too chilly. Bundle up enough to make being outside in the cold tolerable while you do your normal preflight routine. If you’ve dressed for this, you’re dressed appropriately for a winter flight.

Think about how much open space is on the ground when you look out of the cockpit during a flight. In the event an off-airport landing must be made, you’ll no doubt look for a large, clear area to put the airplane down. Are you dressed to walk a long distance for help? What may be a relatively short walk in the summer can seem painfully long in winter when you’re not dressed for it. Throw in the possibility of injuries, and walking for help may be even more difficult.

File A Flight Plan: In the event of an off-airport landing in a sparse area, having filed a flight plan will make chances of rescue more likely.

Dress In Layers: At the very least, bring layers of clothing. You can add them and remove them as necessary. Some airplane cabin heaters don’t warm the cabin very well in cold temperatures, so wearing layers while flying can also add a certain degree of comfort.

Bring A Survival Kit: What goes in a survival kit can depend on the person, the terrain you’re flying over, the weather conditions and so on. Some good winter items would be matches wrapped in plastic, a lighter, a candle, some plastic garbage bags, a knife or utility tool, a small mirror, dry gloves and socks, a sleeping bag, a space blanket, a compact tent, nutrition bars, water, and a first aid kit. A survival kit’s contents should be tailored to the flight and the person making the flight. Use some common sense and ingenuity when packing your own survival kit.

Hopefully, these tips will give you something to think about before your next winter flight. The FAA, AOPA and others have additional information covering all aspects of winter flying, so check them out as well. Stay warm, and as always, have a safe flight!

This entry was posted in Columns, February/March 2015, Wisconsin Aeronautics Report and tagged , , . Bookmark the permalink.

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