Embracing the Cold Weather

After landing just before a strong snowstorm in northern Quebec, we prepared the airplane to stay overnight in the snow. Sarah Rovner

It was a cold February morning on the way to Europe in a single-engine Cessna 210. I was enjoying the performance and steady rumble of the big-bore Continental IO-55O engine. I had my little red booklet on the dash where I continually scribbled down speeds, fuel burn and temperatures as part of my performance log. I needed to know the airplane’s exact performance prior to the long overwater legs ahead. The back seats were filled with survival suits, rafts, and even a hand-crank fuel pump for fueling the airplane in Northern Canada. I was northbound to Milwaukee—one of my favorite overnight stops before launching into Canada.

Though I’m not much for superstition, I do have rituals. In fact, most ferry pilots have rituals. My ritual involved having a tomato-bisque dinner prior to the first day over water. The next morning, I would don my survival suit and cross an icy Lake Michigan on the way to Sault Ste. Marie, Canada.

Ferry flying has always been one of aviation’s most mysterious and thrilling career paths. I receive questions from people all the time wondering how to become a ferry pilot and how to prepare themselves for long-distance flights. My answers are usually the same: planning, knowledge and precision. Although you may not be taking an exotic airplane to an exotic location, the same skills I’ve learned on ferry flights can also apply to a new private pilot. Because of my exposure to far-northern climates, I’ve learned a lot of lessons from ferry flying that could help prepare pilots for the adventures of winter flying.

Though an airplane may be legal for flight into known icing, it’s still possible to end up in a dangerous situation. The Cessna 210 was one of the first single-engine piston aircraft to be certified for flight into known icing in the 1970s. It was equipped for deice boots powered by a vacuum pump, with windshield and prop heat. Though the airplane was certified with this system, the technology is very antiquated and does not meet the certification standards of today’s FIKI aircraft.

View of the runway ­after touchdown when the snowstorm moved in. Sarah Rovner

Along my route, an occluded front had formed that stretched thousands of miles. As I entered the clouds surrounding the boundary of the front, it didn’t take long for ice to start forming on the wings. When enough ice accumulated, I cycled the boots in an attempt to shed the ice. As I looked over to the wings, my heart sunk. The ice was bridging on the left wing while being shed on the right.

I was experiencing a now nearly extinct phenomenon known as ice bridging. Ice bridging is when the boots push the ice out, but the ice doesn’t break off, creating a layer of ice that is separated from the boot by an air gap. Most modern boot systems have more advanced technology to prevent this, but for early boot-equipped aircraft, it was a problem. The wing continued to get heavier, and the performance continued to decline, so I immediately executed Plan B by descending to 5,000 feet where the temperature was above freezing. As the ice melted off the wings, my immediate crisis was averted, but I now had an additional problem: The freezing level across the remainder of my route was at the surface, and I had to avoid icing at all costs.

Spending any amount of time among fellow pilots always produces extravagant stories of survival and ingenuity. I have heard of exaggerated stories and unconventional tricks ferry pilots have used over the years to avoid perilous icing. One pilot swore spraying Rain-X on the wings kept ice from sticking. Another ferry pilot claimed to have descended to 20 feet above the North Atlantic Ocean to use salty seawater spray to clean the wings.

Though I can’t speak to the legitimacy or effectiveness of any of these techniques, I do know they’re not recommended by the aircraft’s manufacturer. As pilots, it’s critical that we operate within the aircraft’s limitations. The good news is, technology can help us forecast icing conditions, and manufacturers have created very thorough procedures for dealing with harsh winter climates in small airplanes.

Parking in the snow on the way to Europe. Sarah Rovner

Knowledge Can Bring Rewards

The most important line of defense against winter hazards is planning and knowledge. Though understanding weather systems and reading charts is a critical skill any time of the year, it’s particularly important when identifying icing hazards in winter. Many of us have not taken an advanced weather course since our initial pilot training, but luckily, there are plenty of ways to gain the knowledge. The FAA Safety Team has published online courses for weather, and there are plenty of FAA advisory circulars dealing specifically with winter weather. Advisory Circular 91-74B, “Pilot Guide: Flight in Icing Conditions,” is a good place to start when learning about icing conditions.

As many of us know or have experienced, not all clouds contain icing. Structural icing is directly related to the liquid-water content of the visible moisture. As mentioned in the advisory circular, ice accumulation is greatest at temperatures just below freezing because clouds contain a high quantity of liquid-water content. Conversely, ice accumulation is nearly negligible when temperatures drop below -4 degrees Fahrenheit as most clouds are made up entirely of ice particles.

When I’d take small airplanes across the ocean in winter, I often aimed for a temperature that was too cold for structural icing to form. But even this precaution is not infallible. While dry snow and very cold clouds are less likely to produce ice than freezing drizzle, we need to keep in mind there is always a risk of structural icing with any visible moisture.

When extreme weather makes the news, it’s usually related to a front, which can be very hazardous to aircraft. Though occluded fronts have a reputation for being especially dangerous, any fronts or convective areas contain the risk of having supercooled water in liquid form. An occluded front consists of a warm air mass trapped in between two cold air masses. This can increase the risk of freezing rain because the warm air produces liquid precipitation, which is then cooled rapidly on descent while remaining in liquid form.

Preheating the frozen engine with a diesel-powered air preheater. Sarah Rovner

Though very cold temperatures provide limited possibilities for icing to form, supercooled liquid water doesn’t play by the same rules. If you are flying through a front or convective activity, and warm air is being forced up, you can still encounter air warm or cool enough in the overall mass to contain enough liquid-water content for structural icing. So even when the thermometer shows very cold temperatures, it’s important to remain alert for icing.

Overwater ferry pilots use every tool at their disposal for weather planning. In fact, before each water leg in a small airplane, I’d look at seven unique tools from several different countries. After all, crossing an ocean in winter in a small aircraft leaves very few options for emergencies and diversions. Some of these include National Oceanic and Atmospheric Administration charts, North Avimet, Gramets (a graphical vertical flight path weather forecast based on the Global Forecast System), Canadian oceanic planning charts, U.K. planning and prognostic charts, and apps such as Windy and ForeFlight.

Most of these tools are free and use multiple sources for their weather observations and forecasts. I like to combine the tools to make my own composite forecast for my flights. Of course, understanding how to use weather tools is critical for survival in a harsh environment such as the North Atlantic, but it is equally as important for taking the local rental airplane out on a cold winter day.

Precision is not only about airmanship but also the ability to operate exactly how the manufacturer intended. Though it seems simple, we must thoroughly understand our aircraft’s capabilities and limitations. Many newer general aviation aircraft now have anti-ice systems installed. While at Oshkosh, Wisconsin, I saw a few companies offering supplemental type certificates to install ice-protection systems on a variety of aircraft.

A common system called TKS, also known as a “weeping wing,” operates by pumping anti-ice fluid out of small holes in the wing, windshield and/or the propeller to prevent ice from forming on the aircraft. While some airplanes are certified for flight into known icing using this system, TKS alone does not always permit the airplane to operate into known icing conditions. If equipped, pilots must keep in mind that a TKS system can be limited by how much fluid is available. It may also require specific speeds and temperatures for operation, and that the system be turned on prior to entering icing conditions. Many systems may also prohibit operation through certain types of visible moisture, such as freezing drizzle or rain.

A spectacular view from the wing of a brand-new Cessna T206 on a clear day over eastern Greenland on the way to Kulusuk Airport. Sarah Rovner

Cold Starts

Setting aside the complexity of North Atlantic weather forecasting and the limitations of anti-ice systems, sometimes even the soloing student grapples with the problem of cold starts. I’m certainly no stranger to the embarrassment that comes from the endless cranking and draining of an already weakened battery in the cold.

The good news is, many airplane manufacturers provide instructions for operating in cold climates. For example, Lycoming recommends an operator should preheat the engine when temperatures are at or below 20 degrees F. If we do manage to get the engine started below the recommended temperature for preheat, we risk running the engine without adequate lubrication, causing damage and excessive wear. For my Super Cub, I have a preheat system mounted on the engine. I preheat the engine when the temperature is below a very conservative 50 degrees F. Preheat kits are inexpensive and usually easy to install, making it a small investment for engine longevity.

Without a kit, another option is to use warm air to preheat the engine. Most major engine manufacturers have published guidelines for using warm air to preheat. This doesn’t mean taking a heat gun to the cylinders on a cold day because too much external heat can melt or damage components. If you live in a southern climate or are on the road with only a few cold days a year, many airports can pull your airplane into a heated hangar the night before your flight for a small fee.

Most discussions about oil temperature revolve around the maximum, but there is a minimum too. Once you get the engine started and you’re ready to launch, make sure that the engine is at its minimum required oil temperature. Oil actually turns into a sludge when it’s cold and does not flow freely through the engine. Most manufacturers also recommend specific types of oil to use in cold climates.

Donning the ­survival suit for the overwater leg to Iceland on a beautiful clear day in Kulusuk, Greenland. Sarah Rovner

If you find yourself operating frequently in subfreezing temperatures, it might be time to think about a winterization kit. In the Arctic, I often witnessed pilots making their own by putting duct tape on the cowling. A better solution is a manufacturer-made winterization kit that includes cowling inlet covers designed to restrict airflow and prevent the engine from cooling too much in flight. Along with other manufacturers, both Cessna and Cirrus offer winterization kits for cold weather operations.

So you’ve done all the planning, but what if you still find yourself in icing conditions? Even after meticulous planning, pilots could still encounter unanticipated icing conditions. Many aircraft have emergency procedures that usually direct the pilot to maintain a minimum airspeed and exit icing conditions as soon as possible. Part of the preflight and weather-planning process should include an icing exit strategy—whether it be an altitude change, flight-path change or even a diversion. I always made it a point to know where warmer air was and where the clouds were. Reviewing the emergency procedures and keeping them fresh in your mind is another way to make sure you’re prepared.

Though most pilots will not fly a small airplane over the North Atlantic, the tools and techniques can apply to everyone. There is no doubt that flying piston singles in far-northern climates will yield very harsh conditions for pilots. Experienced pilots know the importance of planning, knowledge and precision, but it’s something all pilots can easily learn.

Even after some close encounters with the perils of winter flying, I do not hesitate for a moment to fly my Super Cub on a cold day. Having a Plan B, being prepared and maintaining proficiency are the most important risk-mitigation strategies any pilot must have.


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