Flying Through the Winter

I grew up in Central New York State, where, like much of the northern United States, winter is really winter. I learned to fly at a small airport with a turf runway. Needless to say, a snowplow was not welcome on that turf. But the first major snowfall of the season did not mean putting the airplane in the barn till spring. It meant that the Piper PA-17 Vagabond stood proud on skis. Of course, along with the skis came all the other considerations of operating in the seasonal environment. As the years passed, the turf runway was replaced by asphalt and our attention shifted to icy runways, taxiways, and ramps. But regardless of which landing gear was installed, the other considerations remained.

I spent a good portion of my general aviation life operating in climates that hosted a robust winter season. I learned many lessons about winter flying as I progressed from that PA-17 into some very sophisticated and complex airplanes and the higher altitudes and longer ranges they allowed. Perhaps the most important lesson is that winter flying requires considerably more planning and preparation. And we must maintain a mindset that sometimes it is prudent to just stay indoors and read about flying.

Planning and Preparation

The planning and preparation must begin well before the planned departure time. The study of the weather needs to be thorough and detailed. A plan to climb through a cloud layer to clear sky above might be customary in warm weather but might result in acquiring a load of structural ice in winter. Any negative result from an error in planning can be magnified significantly in winter. The likelihood of needing to divert to an alternate airport is increased in winter. As much extra fuel as weight and balance permits is a good idea.

Knowing the surface conditions at all airports of intended landing and at planned alternates must be researched. Snow removal is not equal for all airports. Ice on runways is difficult to control at even the best equipped airports. Also, knowing expected wind conditions at expected arrival times is important. Crosswinds and gusts are more difficult to manage when the runway is slippery. Of course, we should always check NOTAMs, but a call to the airport might also be wise.

The planning and preparation must also consider the need for warm clothing and survival gear. Warm clothing is important not just for survival in an emergency, but also for good pilot performance. Prolonged exposure to cold temperatures decreases human performance over time. And we want to avoid the temptation for an abbreviated preflight inspection because the cold is uncomfortable. Many online resources are available to help determine what survival gear should be carried depending on the flight. My advice is to always assume that you will be spending the night in the terrain over which you are flying and to always file a flight plan regardless of the weather.

The Airplane

Winter flying requires that much more attention must be given to the airplane. An operating carbon monoxide (CO) detector is a must. Virtually all reciprocating powered GA airplanes rely on combustion for the cabin heat source. Single-engine airplanes typically employ a heat shroud around the engine exhaust and duct the flow of fresh air through the shroud. Any crack in the exhaust will feed the deadly CO into the cabin. Many multiengine airplanes rely on a fuel-powered combustion heater in the nose. Combustion produces CO and a malfunction can again send CO into the cabin. A review of procedures in the event CO is detected is also prudent.

Tire pressure should be checked, especially if the airplane has arrived from a warm destination and has spent the night in the cold. The battery also deserves due consideration. A weak battery in a warm climate will probably be a nearly dead battery in the low temperatures. Any airplane that is highly dependent on the electrical system will likely have problems with a low battery. That is especially true if the gear system is electrically operated. If a jump start is necessary to get the engine started, attempting to retract the landing gear after takeoff can cause an electrical failure. Be sure to check the manufacturer’s recommendations regarding the correct engine oil for the anticipated temperatures. Again, an airplane based in a warm climate may have been serviced with an engine oil that will not perform well and can possibly lead to severe engine damage when operated in very cold conditions.

We should also plan for obtaining engine and or cabin preheat if anticipated ambient temperatures call for it. The manufacturer may specify preheat below a certain temperature. The best situation is to keep the airplane in a heated hangar, but that is not always possible or practical. Moving an airplane that has been parked outside into a heated hangar for deicing can be problematic. If there is a substantial amount of snow on the airplane, water may pool in unwanted places as the snow melts. Then, a takeoff into cold air can result in water refreezing and interfering with flight control or trim function. An unheated hangar is of course preferable to using a tie-down on the ramp. At least that largely prevents snow, ice, and frost from accumulating on the airplane, but again obtaining hangar space for transient airplanes is frequently impossible or impractical. In any case, all snow, ice, and frost must be removed from the airplane before flight. Deicing fluid is the best method, but it is usually not available at the smaller GA airports. Mechanically removing the offending material with a broom or something similar is often the next option. Preferably, we will use a broom that has been dedicated for this task. Any broom is better than no broom, the one used to sweep the hangar floor has a good potential for scratching the paint.

For airplanes parked outside, monitor snow accumulation on the rear horizontal surfaces. Excess weight can cause the airplane tail section to strike the ground, sometimes producing damage. For hangared airplanes, monitor the snow accumulation on the hangar roof. Too much weight on the roof can cause a collapse severely damaging the airplane inside. If the snow cannot be removed from the roof, it is better to move the airplane outside and tie it down until the danger of collapse is no longer present.

Preflight Inspection

A few additions must be made to the Preflight Inspection Checklist for operation in winter weather. As mentioned previously, wearing warm clothing for the preflight inspection is essential. Every opening in the fuselage has a purpose and can cause problems if blocked by ice or snow. Many of these openings are vents for a variety of functions. Snow, slush, and ice can block any of the openings and must be removed before flight. Not knowing the purpose of an opening is not an excuse for not checking it before flight. One of the most important vents is the oil breather tube which might be a plastic or metal tube extending from the engine. If you do not know the location of the all-important oil breather tube, be sure to locate it before your next flight. If the breather tube is blocked by ice or frozen, excessive crankcase pressure can blow out seals causing loss of engine oil followed by complete loss of engine power. There are other critical openings as well, including fuel system vents, and of course the pitot and static openings. Regardless of how cold it is outside, taking a fuel sample from each sump is essential. We obviously want to check for water in the fuel system, but also note that a frozen sump valve indicates the presence of water somewhere that it should not be.

Taxi

Extra vigilance is necessary for safe taxi operations in winter conditions. With some exceptions, airport surfaces are generally not chemically treated as are roads, so ice and hard-packed snow are common. These can be extremely slippery, especially if the sun has come out and a thin top layer of water is present. Add some wind to this and taxiing can become a challenge. Correct control position based on relative wind direction is important. Keep the speed slow during taxi and plan on turns being wider than usual. Watch for higher snowbanks that might not be cleared by the wings. Be aware that snow drifts can obscure signage and markings can be covered with a layer of snow. Use the brakes sparingly and gently. Beware of sliding on the slippery surface during run-up. Also, be vigilant for snow removal vehicles which may be on or crossing taxiways and runways.

Takeoff and Landing

The takeoff from a slippery runway again requires attention to the correct control position based on relative wind direction. Also, a go-no go point should be selected closer to the starting point to allow more distance to get stopped in the event of a need to abort.

Like any landing a stabilized approach is essential. Beware of the possibility of snowbanks just before the runway. This is most common if a road passes close to the arrival end of the runway and the plows have cleared the road without regard to the approach path. In some lighting conditions, a snowbank can be very difficult to see. After my second solo flight, my CFI took me to the approach end of the runway and showed me three distinct slots where my tires had passed through a snowbank. Fortunately, the snow was not hard-packed nor frozen. Once on the ground, use aerodynamic braking as much as possible and be alert for a crosswind blowing the airplane off the side of the runway. Use only the minimum brake pressure necessary. Small, GA airplanes do not have anti-lock brakes and other stability mechanisms built into modern automobiles.

Worth mentioning is the temptation to land on a frozen body of water. While a large expanse of open water that is frozen may look inviting, landing is ill-advised. It is nearly impossible to judge the suitability from the air. The thickness of the ice cannot be visually determined, and even thick ice can have cracks that will be opened by the weight of the airplane. It is best to leave landing on frozen lakes to the professional bush pilots. There is only one FAA-certified ice runway in the U.S. It is in New Hampshire, and it is carefully monitored when it is in operation. It is still very slippery and extreme caution is advised.

Summary

So, while winter flying can be fun, it must be taken very seriously and requires extra planning and preparation, as well as very close attention to the weather, the airplane, and the airports of intended use.

Gene Benson has had a lifetime of aviation experience.  He has lived and breathed aviation from his first official flying lesson at the age of 14, to his first solo on his sixteenth birthday, to his 8,000 hours of flight instruction given. He has served as the Dean of Aeronautics for an aviation college, as an instructor for a major domestic airline, consultant to several foreign and domestic airlines, and to business aviation.  His academic background includes degrees in psychology, education, and business. His specialty now is the application of human factors to error reduction and safety in aviation and other industries. He is presently a FAASTeam Lead Representative and has recently served as a member of the NBAA Safety Committee. View Gene’s work at genebenson.comand https://www.vectorsforsafety.com/.

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