Winter Flying

Follow these winter flying tips this season.

(December 2011) If you live in a snowy climate, chances are good your logbook looks a little thin during the winter months.

It’s happened to me.

I started flying for transportation shortly after I moved to Connecticut in the mid-1990s direct from sunny southern California. Even after I had my instrument rating, the winter played havoc on my travel plans, and every year despite my efforts to reverse the trend, I wound up flying a lot less than normal from around late November through early March, give or take an early or late snowstorm. One year I had to cancel four trips in a row up to London, Ontario, Canada, due to heavy snows.

That’s winter life if you live and fly in a cold place. Sometimes, actually, the flying is the easy part. The real challenges are often found while getting ready to go flying or getting back from having flown.

Over time I developed a number of ways to cope with the winter months, and after a few years, I got the hang of it.

The secret is to make like a Boy Scout and be prepared. With winter flying, it’s critical. From your preflight planning to arrival at your destination, cold temperatures and uncertain conditions demand an attention to detail and a discipline that few pilots practice on sunny days. Some of the tricks you can use to make cold weather operations safer and saner are just common sense. Others are tricks developed out of necessity by pilots who have been there before. As you gain experience, you’re likely to come up with your own strategies and techniques to cut down on the chills and lessen the inherent risks associated with off-season aviating.

Understanding the Weather Map
At the risk of stating the obvious, winter weather works differently than summer weather does. Storms are generated in different places. The weather they spawn is for the most part fundamentally different. The ways they develop, evolve and degenerate are also different.

The way storms form can be at once local and the results of phenomena a thousand miles away. Understanding how it works can give you an edge when it comes to planning your flight and also planning your deviations, if necessary. In winter, local knowledge can be key.

Global knowledge helps too. The upper atmosphere is where winter storms are hatched. An area of low pressure aloft — a trough — will generate surface lows, which will spawn storms if given half a chance. The necessary ingredients are cold air — often provided by Canadian continental air masses moving south (remember that trough) — combined with moisture (the Gulf of Mexico is the big contributor here) and lifting, which requires only two air masses meeting and not hitting it off. The result can be widespread storms with snow, ice, sleet, freezing rain, reduced visibility and contaminated runways. All of which ratchet up the risk.

So knowing what the weather is and what it is forecast to be is crucial, as is being prepared to make alternative plans if the weather changes, as it is more apt to do in winter than summer.

Before launching on a trip, study up. As much as a couple of days before the trip, start looking at the weather pattern and seeing how that compares with the forecast for your departure time and return. Over time, you’ll start to see patterns for how storms form and what areas are likely to get precipitation as a result.

In recent years, a number of excellent new or enhanced weather products have come to the fore, particularly in the mysterious realm of icing forecasts. The government’s maximum icing forecasts are better than ever and are highly and easily customizable. Depending on what kind of airplane you fly, the severity of the icing predictions can help you make the call about when to go, how high to fly or whether to go at all or wait it out.

When it comes to making preparations for winter flying, much of a pilot's energy will be spent making sure that the engine will start and that the airframe is free of ice. The best way to do this is to keep your airplane in a hangar (a heated one is that much better) and pull it out only when you're ready to fly. On the other end of the trip, it might not be so easy to find a place to keep your bird, though if you can and if there's precipitation expected, it's hard to imagine a price that would be too high for a couple of nights in a warm hangar. If there's no such option, you need to deal with the buildup of ice and snow on the airframe before you can go flying.

I’ve seen pilots show up at the airport on a windy 20-degree day with nothing more than a thin jacket and light gloves to do their preflight. I’ve seen those same pilots get into airplanes still partially covered with snow and frost and fly away. It’s playing with fire to approach winter flying that way. Dress very warmly; you can always lose layers once you get into the airplane. Wear boots and heavy, waterproof gloves. Wear a good hat and a scarf or ear muffs.

Do whatever you need to do so you can perform a real preflight check, which might include getting the snow and frost off of the airframe. I always bring a couple of big Turkish towels to help with this task. It takes a while but it’s worth every second. If you’re going out of an airport where they can spray the airframe with glycol, that’s a great bet.

Engine care is also critical. Know your engine and what it likes and doesn’t like. Be sure to use the right oil for the temperatures — oil that’s too thick for the conditions will act like glue and effectively prevent your reciprocating engine from reciprocating. The heated hangar, again, is ideal, but lacking that, invest in a preheater. There are several types ranging in price from affordable to something well north of there, but what they have in common is that they are far better than the alternative.

It’s important to follow the manufacturer’s recommendations for starting an engine when it’s cold, especially when it relates to cranking time. Don’t guess. Use a countdown timer or look at a watch with a moving second hand to time the duration of both the start and the rest cycle. Despite the frigid temps that are making the start difficult, starters can heat up quickly if abused. And if they’re abused, they can let you down and leave you in the cold.

Carefully check for ice in the most dangerous location, the fuel tank. If there’s water in the fuel, it will turn to ice, and if it does, it can get into the lines and filters and starve the engine of fuel, perhaps at the most inopportune time. When it’s really cold outside, it’s critical to drain all of the sumps and not just the lowest one. If water in the fuel has indeed frozen, it’s time to head to the hangar, pour yourself a cup of coffee and let things warm up for a while.

Hazards in Flight and on the Ground
The lovely thing about winter flying is that it keeps you on your toes, because there are hazards to be encountered in every phase of flight, and beyond.

Without a doubt the greatest threat to safety in winter is ice. On many a winter day the icing level starts at the surface and climbs high into the flight levels. How you respond to icing threats depends on a number of things: what kind of airplane you’re flying, what kind of equipment it has on it, the severity of the icing and the expected extent of the icing (that is, how widespread it is and how deep the icing layers are).

The scariest kind of ice comes in supercooled large droplets, or SLD. Oddly enough, you get this worst kind of icing most frequently when temperatures are relatively warm and when warm air has climbed above a colder mass. The rain that falls comes down in large droplets and freezes on contact with anything cold and metal — composites are not immune. Unless you’re in it for a very short time — and nobody wants to make that bet — the only option is to get out of Dodge, either by climbing to warmer air, where the precipitation originally started falling as rain, or by turning around and either landing somewhere that’s not getting ice or finding a route that avoids the freezing rain, remembering that such systems can be very widespread. What’s the right answer? Again, that depends on all the factors previously discussed, but any time the wrong answer can ruin your day, it makes sense to fly conservatively. In some cases, that will mean escaping the icing conditions as soon as practical and waiting it out.

On arrival and approach, ice and snow can change the way you fly. Snow falling is very pretty but harder than all but the heaviest rain to see through. Moreover, when you do see the runway environment, you might be greeted with a contaminated runway surface. How contaminated is too contaminated? Again, it depends.

There are so many variables — wind, amount of snow, what’s underneath the snow (dry pavement or a layer of ice?) and what kind of equipment you’re operating, as well as your experience level — that you really need to think carefully about how you make that landing and whether you even want to. The wisdom of those who have landed just before you is invaluable. Get the braking reports, and if there aren’t any offered, ask for them. Controllers are usually very accommodating in asking pilots who have just landed to pass that information along to arriving flights.

Winter comes to play with a long list of unpleasant traits, but with the proper preparation, planning and equipment (not to mention an abundance of caution), flying on those shortest days can be profoundly rewarding. In fact, when you’ve pulled off a well-planned and carefully executed flight despite the cold, the wind and the snow, you have done something to be proud of. Moreover, the lessons learned about planning, preparation and risk management can be applied to your flying every season and every day of the year.


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