A fellow pilot once asked, "How long does it take to check out on skis?" I looked at him and said, “About three years.” He looked back at me with the same tilted head that you get when you talk to your dog, and he’s not quite sure what you’re talking about. The truth is I have almost 25 seasons of flying on skis, and I still don’t feel like I’ve seen it all. Every season, I learn something new, usually as a result of mistakes. Sometimes I bruise my ego, other times I’ve bruised the plane. Bruising the ego is better.
Flying on skis is closer to flying on floats than wheels. So even though you technically don’t need an endorsement, you should absolutely get yourself some instruction before you just strap them on and go.
I’ve heard that the Inuits have over 100 words to describe snow. My vocabulary is much more limited. The variables that’ll have the greatest influence on your performance and technique will be the depth and consistency of the snow. Is the snow deep or shallow? Is it dry powder? Heavy wet? Crusty? Icy hardpack? Temperature will play a huge role in determining consistency. You can take off from hardpack on an early March morning, and come back to land on mashed potatoes in the afternoon. Heavy wet snow equals lots of drag, and as it becomes more on the order of a frozen slushy, you’ll get stuck. Shallow snow of around six to eight inches, or snow that has compressed itself or been matted down to hardpack, is great for learning. Deep powder that can sink the plane above the tail feathers should be avoided until you get some time under your belt. The same goes for pure ice and heavy crust.
There are three basic types of skis. With wheel-replacement skis, the wheel is removed and substituted with a ski. On a penetration ski, the wheel extends down below the ski for operation on snow and pavement. The retractable ski allows the ski to be retracted above or pumped below the tire, usually via a hydraulic pump. In my opinion, the wheel-replacement ski will give you the best performance due to overall flotation and light weight. They’re usually the least expensive, as well. On the downside, you’re pretty much limited to snow, although for many models, you can buy dollies to move the plane around on hard surfaces. The penetration ski will cost a bit more but offers lots of convenience. Downside: The tire sticking below the ski presents more drag and longer takeoff runs. The retractable ski offers the best of both worlds, but it usually means more weight, and plumbing can be a bit spendy.
All skis come with rigging, a front and rear check cable, and a bungee or spring. The check cables run from the tip and tail of the ski to tabs on the fuselage, and a bungee or spring runs from the tip of the ski to another tab. The bungee is there to hold the ski tips up in flight, and the cables are there to stop the ski from spinning around the axle if the bungee snaps. If you’re running in deep snow, then it’s advisable to run a tail ski, as well. In shallow snow a foot or less, I prefer to run without the tail ski because I can use the tailwheel as a brake if I need to by simply pulling back on the stick.
If you keep your plane tied down outside, then you must put a barrier between the skis and snow so you don’t freeze in. I use two-inch PVC pipe—it’s lightweight, and the skis don’t stick to it. I just place a few pieces under the tip and tail of the ski, and when I’m ready, I can just taxi off. I also carry a small shovel and snowshoes. If you get stuck, you may need to dig out around the skis and then use the snowshoes to mat down an area in front of the plane.
Due to the variations in snow depth, consistency and lighting, there’s no “one size fits all” technique. Starting out, you have to remember that on snow, you have no brakes, and your turning radius will be much larger than on wheels. And once you get moving—unless you’re on a hardpack—there’s no stopping. You have to plan your taxi route and turns ahead of time. Do your before-takeoff checks and run-up before you leave your tiedown. It’ll take a fair amount of power just to move the airplane, especially in deep or wet snow—keep an eye on engine temps.
After you get the plane moving, relax the stick, and at times, use forward stick to keep the tail light. This will aid in making turns. By the way, steering is vague at best, sort of like a boat with a rudder that’s too small. If you plan your turns to the left, you’ll get a tighter turning radius due to the left-turning tendencies. As you enter the turn, use forward stick and fairly short, powerful bursts of power to energize the rudder and blow the tail around. As the turn progresses, you may start to slide sideways. It’s fun, but too much can damage your landing gear. You can limit the side-slide with a touch of outside rudder, and then go back to the inside rudder, almost segmenting the turn. Once you’re in line with the takeoff area, don’t hesitate—go right to full power. Allow the tail to rise up out of the snow but keep it tail low. As you accelerate, the skis will begin to plane up, feeling a bit like a floatplane when it gets on the step. There’s a “sweet-spot” pitch attitude that’ll allow quicker acceleration. If you allow the tail to come up too high or hold it too low, you’ll feel the airplane decelerate. Get it right, and it’ll pretty much fly itself off.
If you’re landing on snow that’s already matted down or hardpack, you can pretty much make a normal power-off landing. If you’re landing on virgin snow that may be deep, fly a series of long touch-and-goes and overlap the tracks. This way, you’ll mat yourself a runway. Oh yeah—if you’re landing on a frozen lake and the tracks turn dark, it’s overflow. Don’t land there! If the snow is soft and deep, land with power “soft-field style.” After you touch, keep enough power on to keep the plane moving. When it’s time to turn, jink slightly right then turn left back into your tracks and back-taxi for takeoff. If you’re going to stop, be sure to let your skis cool down for a minute then pull forward onto matted snow. Put something under the skis if you leave the plane for a while. (In a pinch, you can use pine boughs or sticks.) If you try to taxi and the snow is a bit sticky, you can try to break free by slightly raising and lowering the tail; use a fair amount of power and wiggle the rudders left and right. It works...sometimes.
Skis can open up a whole new world of places to land. There’s nothing like landing on fresh powder on a crisp winter’s day where no one else has been. Very cool!
Damian DelGaizo is the owner of Andover Flight (www.andoverflight.com) and has over 15,000 hours of tailwheel time.