The magic of winter flying
PUBLISHED: 09:00 19 March 2021
Caroline Mathon 2021
The magic of winter flying - landing on mountain sides & frozen lakes, soaring over snow covered fields in your own winter wonderland
It’s winter, a season of rainy days, low ceilings, poor visibility, horizontal windsocks and flooded grass airstrips. No more fly-ins, no more flying at all for some of us, no more BBQs at the airfield with friends (and Covid does not help!) Aeroplanes stay in damp hangars and wait for better days. So do many pilots.
A bad time? Well, not always and not for everyone. As everybody knows, periods of low pressure alternate with anticyclonic conditions, which can bring some foggy days over low ground but always provide brilliant flying weather in the mountains. In my opinion, it is the most wonderful time of the year for flying: the air is crisp and calm, there is hardly any wind and the cold OAT allows extra-short takeoffs and astonishing rates of climb, as if your aeroplane was as happy to fly as you are. It would be a pity not to go flying in these conditions. In fact, all year long I look forward for the four or five months, usually from December to April, during which I can practise winter flying, which has for a long time been my favourite activity.
I know at least two ways to put some fun into your flying during winter: landing on mountain strips and on frozen lakes. Of course, both of them call for a ski-equipped aeroplane.
Who remembers Herman Geiger? When I was a schoolboy in the mid sixties, this nowadays forgotten pilot was a hero−a kind of idol for me and some of my schoolmates. Yes, in those days, most kids wanted to become astronauts, or at least pilots, not football players or finalists in The Voice. But I digress... Using Piper Super Cubs in the beginning and Pilatus Porters later, Geiger was the man who really pioneered the technique of landing on slopes. Until he passed away in 1966, he used the method he had discovered to make thousands of rescue flights for both human and animals in the Alps of Switzerland, his native country.
Fast forward thirty years, and I was now a private pilot. I still remembered the achievements of the Swiss pioneer and really wanted do what he did, albeit just for fun and not for rescue purposes (helicopters were now doing this job much better). Flying Piper Super Cubs to get my mountain rating, I discovered the exhilaration of this activity and it turned into an addiction to me. As I could not afford a PA-18, I decided that a Jodel would be just as convenient for mountain landings, as this kind of aeroplane was widely used by private pilots for glacier landings in the Alps. So, I soon become the proud owner of a Jodel D119. The first thing I did as soon as I brought the aircraft to her new home was to have a radio installed. And the second one was to get a pair of skis to fit on her.
So here I was with my new Jodel fitted with new skis, the magnificent Pyrenean range just a few miles from home in France and the gorgeous Alps and their glaciers just four flight hours away. My first landings on snow with this aeroplane were marked by a sort of shyness. But after several seasons of training and a few hundreds of landings on snow, I managed to get some experience (or, more exactly, I assumed that I had got some experience). So, I tried more difficult airstrips and made my first landings at places where no aeroplanes had landed before.
The mountain rating
So, how do we land on those mountain airstrips, known as altisurfaces in France? To be allowed to do so, an FCL 815 ‘mountain rating’ is compulsory for access to all sloping airstrips in France, Italy and Switzerland. In other countries of EASA-land, the landowner’s permission is sufficient, because there are no official mountain airstrips in their respective AIPs. That’s it, as far as the rules go−now let’s get flying!
The first thing to do when you arrive over the place is to have a good look at it. In fact, I should have written a very good look at it. Have aeroplanes already landed here? The shape, length and size of their tracks will give you valuable tips about the quality of snow. Is something moving on the ground? If there are animals, try another place in order not to disturb them. If there are human beings, whether skiers or hikers, carefully check where they are, which way they are proceeding to, and make sure they have heard and seen your plane and will not cross your path when you land or take off. Do not forget to figure out the direction you would follow if, for any reason, you had to go home on foot. Then make several passes over the “runway” you have chosen, to ascertain the aiming point for landing, the point where you will stop after landing or make a U-turn and−most importantly−the takeoff direction. And if you have any doubt about takeoff, do not attempt to land there: try another altisurface, or come back home. Remember; we fly for fun, not to save lives! A last low pass to check the wind, the turbulence and to notice the exact elevation of the strip, and you are ready for the circuit.
And now here we are, on final with full flaps−if we have any−the same approach speed as on a flat runway and a stabilised rate of descent. In the windscreen, there are now just two things: a clear blue sky on top and a huge white area below. We are aiming a few metres before the expected touchdown point. During the roundout, the engine cowling hides the runway, and right after that, we feel the skis smoothly brushing the snow. The speed decreases immediately, so it is time to apply more power to reach the top (you are going uphill). At this point we have to decide: make a slow U-turn, then apply full power and takeoff for another circuit, or stop the engine, jump in the snow and enjoy the gorgeous landscape around us. This second option is not always possible, but when you are lucky enough to do it after a couple of touch-and-goes, do not hesitate. A picnic in the snow at several thousands of feet of altitude on a sunny day, with glittering peaks all around you, is a real treat.
When it is time to leave this wonderland, double-check the takeoff direction by fixing on a landmark in the distance. Does the field seem short? Yes indeed it may be short, but the slope will help acceleration, and the steeper the slope, the shorter the takeoff and landing distances. I am still amazed how the Jodel on skis can use altisurfaces which have an average length of two hundred meters (sometimes less) and would never dare try this on a flat runway of the same length, even unobstructed.
Mountain flying is not just a different technique, it is also an excellent way to discover wildlife. Unlike what lots of people might think, animals are not scared by aeroplanes. They have understood that our little aircraft are not dangerous for them. And they even sometimes enjoy playing with pilots! I remember one day when, just after takeoff from a mountain strip, I saw a fox trotting on the snow. As soon as it heard the plane, it stopped, looked up and saw me. I circled the beautiful little red fox and distinctly saw that it was following the plane with its eyes. I flew away, it was still staring at me. I decided to overfly it once more, and we soon begun to play hide and seek. The game lasted for about ten minutes. The fox could have easily disappeared in the woods if it had been scared, but it stayed on the snow, running from one side to another while looking at the plane. Unfortunately, my ETA had nearly elapsed and I had to give up before somebody on the ground declared an emergency. But when I flew away, I saw the fox sitting in the snow and still following the Jodel with its eyes.
Another day in early winter, my wife Caroline and I were heading for the peaks in our faithful Jodel when she suddenly spotted “something brown moving on the snow”. We flew closer and realized that a family of deer had been surprised by the early snow and was struggling to reach the nearest forest where they knew they would be safe and find some food. All was going rather well for the adults, but the poor little fawn was wading in the snow in spite of encouragements from mum and dad. At last the whole family succeeded in taking cover and disappeared in the woods. If they had not, we would have had to go back to the airfield, load the Jodel with some hay, land up there and provide it to the deer, exactly like Hermann Geiger did when he used his plane, among other things, to feed the alpine chamois.
The meeting with the fox and the deer family occurred randomly and involved a lot of luck. But you can sometimes create some poetic moments by yourself. I took off one morning just before sunrise and headed to the peaks with the idea of landing somewhere to have breakfast up there. The more I climbed, the more luminous the sky became and when I arrived at the planned landing strip, the snow was not white at all, but light blue in the shadows and pink on the sunny areas. That was a fantastic moment to land on what looked like an enormous candy. I stopped the engine to enjoy the silence and ate my freshly baked croissants while looking at the sun rising over the ridges. Even at 6,500ft, the temperature was mild, it was the end of April, the birds woke up and started singing (just for me?). I already knew that it was the last flight on skis for the season. Back to the airfield, I would change the climb prop for the cruise prop, replace the skis with wheel fairings and put away my winter clothes on a hanger, looking forward to the next winter of wonderful flights.
Landing on lakes
As readers know (see Pilot November 2020), Caroline and I now live in Sweden and our fully refurbished Jodel is based in Sveg (ESND), nearly in the geographic centre of the country. And, of course, the skis and climb propeller moved with us, so as soon as the first winter came, I was eager to try them in our new environment.
What a difference! Here in Sweden there are mountains, albeit not as high as the Alps or even the Pyrénées, but no official mountain strips. Or, to be more precise, there were no strips when we arrived, because I have now received permission to use three private landing places on slopes close to a ski resort in Härjedalen. And it was not an easy job to find suitable places, because the ground is mostly covered by rocks, and where there are no rocks it is often a designated natural reserve or an area reserved for reindeer herding by the Sami people. But the lakes seemed welcoming. There are dozens of lakes in our area, some of them short and narrow and some longer and wider than most airfields, but most of the time surrounded by high trees. And as in Sweden the water has no owners, no permission is required to land on them. So far so good, I thought, every frozen lake with a decent size is a place I can land on, as long as the ice is covered by a layer of snow. But I talked with people in our village, especially those using snowmobiles, and they warned me: yes many lakes can be used, but not all of them, and certainly not those which have a dam at one end, because sometimes the water under the ice is pumped by electric power plants for regulation purposes. In these conditions, ice no longer rests on water and therefore becomes weaker.
So sticking to natural lakes is a safe option, and obviously to those with a decent layer of ice. So how thick is thick? There is a lot of literature on this subject, including a rather dubious formula which showed me that a Jodel at MTOW could be landed on a layer of ice as thin as four inches. That is not much, I thought, and even if I double this figure, that is still not enough in my opinion. So I prefer to use the rule of thumb used by some Canadian pilots: three feet thick to land a DC-3 on skis, two feet for a Twin-Otter and one foot for any single-engine aeroplane. And that includes the De Havilland Beaver, which is four times heavier than a Jodel.
But there was another question worrying me: how do you estimate the thickness of the ice from above, just by looking at the lake when overflying it? The answer is simple: it is impossible. Nevertheless one tip can be used: if the temperature has been well below freezing for several days in a row, it is a good omen. But do not take it for granted, the locals warned! So, be content with a touch and go if you have any doubt. Another useful tip is to look at the tracks left by snowmobiles: most of these vehicles are nearly as heavy as a light aircraft. If they do not dive through the ice, a Jodel will not do either.
Red skiing kit
So now, do you fancy a winter flight in the North? Dress in your best red skiing kit and let’s go to the airfield! In Sveg, the runway and apron are kept ‘black’ (that is, free of snow) all year long by the very helpful airport staff, due to the daily arrival from Stockholm of the local airline King Air. To let the engine warm up, we taxi slowly to the fuel station and fill up the tanks to get three hours of endurance. As the expected duration of our flight today is around ninety minutes, that will make for a safe diversion if necessary, because there is not another available airfield just behind every hill around here. And taking off with full tanks, skis, emergency gear and two persons on board would make us overweight.
Right after takeoff, the landscape is revealed: white-capped mountains in the distance, boglands covered in snow and tortuous frozen rivers below contrast with dark pine woods. We don’t need to climb very high today, one thousand feet agl will be more than enough, also because visibility is in excess of fifty miles. The sky is clear blue, but the sun is still quite low on the horizon in this January morning, providing long shadows and distinct details of the ground. At cruise altitude OAT is minus twelve degrees Celsius and it is not much warmer in the cabin, so we keep our gloves and bobble hats on. With such a low temperature, stopping the engine after landing on a lake is out of the question today−I do not want to take this risk when below minus six degrees Celsius. In my opinion, oil temperatures drop too quickly in this scenario and trying to start an engine which is neither hot nor cold is too hazardous without the insulating engine cover (and we do not have it with us today).
Cruising at 85kt, our destination is soon in sight: a wide frozen lake with a village nearby, covered by an immaculate layer of fresh snow. The snowmobile tracks will not help today, but a group of cross-country skiers has gone along the lake and are having a coffee break on the ridge. We need several passes to check for jutting rocks or other obstructions, while the skiers are looking at the aircraft and waving at us. Everything looks good, so we go for a trial. We get established on final with one notch of flaps at 65kt, aiming for something flat, wide and white. The pine trees on the sides help to estimate height over the snow. We begin the roundout and wait until we feel the skis softly brushing against the snow: applying full throttle, we have to judge how the plane gains speed. Well, not so bad... and soon we are airborne again, over the trees at the end of the lake. We take a look at our tracks. There are no dark stains protruding, so that means that there is no water between the snow and the ice. The place is safe and if we wanted to, we could stop on the lake, make a U-turn and use our landing tracks for takeoff. But today we will be content with a couple of touch-and-goes.
The second one is made with full flap and we land a few metres short of our first track, then apply just enough power to keep some lift on the wings and slide along the lake, thus lengthening our tracks before being airborne again. This kind of landing is excellent to keep your skills current and is really exhilarating, as you feel you are a pilot and a skier at the same time. A third landing in our tracks, just for the fun of it, and off we go. Why further disturb the tranquility for the skiers nearby? Let’s try another lake!
A short flight from here lies a rather narrow, but rather long lake in the middle of a little valley. A Super Cub has landed there and its pilot is digging a hole in the ice with what looks like a big corkscrew. No doubt Nils has decided it is a great day for fishing! However, sitting near a little hole on a folding chair and waiting in the cold for the fish to come is not my favourite pastime, not to mention the smell in the cabin if you do not come back empty-handed, so we head for a third place to carry on our own activities.
On the ridge of a big lake surrounded by a pine and birch forest, something is moving among the trees. Something big, brown and rather slow: a moose. No, not one moose, but two, five, seven, a whole family! Undisturbed by the noise of the engine, they continue to graze the fir needles. Even if the place is safe to land, we won’t stop here either: these animals are usually not aggressive, but rather unpredictable and a moose which decides to run just in front of the propeller could ruin our day. Fortunately, these big animals seldom venture on lakes, so this does not prevent us from trying a few additional slides on this white immensity, using the same technique as previously, while keeping a good look at the moose to make sure they have not yet finished their lunch.
But time flies and the sun is already going down. Sveg is just minutes away, so we soon join overhead, lift the skis to expose the wheels and approach the black runway, easy to spot in the middle of all this white. Black it is, but this does not mean it is dry, and a thin layer of ice remaining on the asphalt can generate a slippery surface and consequently, a poor braking action. So the minimum approach speed is required and, most importantly, no braking at all until the plane comes to a stop. Fortunately, the runway is long and a light headwind is welcome.
After a careful taxi to the flying club’s hangar, it is time to rush into the little airport terminal for a cup of coffee or a warm chocolate, the mind still full of these new sensations.
That’s what winter flying is about: a little bit of skill, a permanent communion with nature and wildlife, and above all moments of intense emotion interspersed with periods of subtle poetry. All this reminds me of the very romantic Symphonie fantastique. I bet the great Hector Berlioz would have loved to own a ski-equipped aeroplane. Or maybe he did?
Winterising your aeroplane
Changing from a cross-country aeroplane to a winter machine is not straightforward, but can be completed in a couple of hours at the beginning of the season with the following modifications.
Skis: wooden skis are no longer used. Metal skis are strong, but they are heavy and often create a lot of drag. GRP skis are much lighter, easier to repair and slide very well, so I use a pair of these for my Jodel. Most of the time, the ski lifting device is operated hydraulically by means of a hand pump in the cabin, but I now have SKF electric actuators and two little knobs on the dashboard to change from wheels to skis (or the opposite) in a matter of seconds – this happened thanks to Caroline who wanted a safer system and was fed up with hydraulic oil leaks on her shoes! I also designed a little fixed tail ski with the wheel protruding permanently.
Propeller: a fine-pitch prop is a must, to make takeoffs on skis easier and keep a decent rate of climb to counteract the additional weight of the skis. Mine was made in France by Alain Léger according to figures I had calculated: 1.0m pitch and 1.8m diameter with broadish blades. It suits a Continental O-200-equipped Jodel perfectly, as long as you accept to fly 15kt slower than with a cruise prop. Plate to blank off the oil cooler: this helps keep the engine warm in flight: I get eighty degrees Celsius at cruise power when OAT is minus fifteen degrees Celsius, instead of the too-cold sixty degrees that I noted previously in the same conditions. This is the cheapest and lightest winter-flying modification, but very useful.
On the advice of Swedish aircraft owners, a Tanis engine heater has been installed. Since the aeroplane has moved to Sweden, it has to cope with much colder temperatures than in France. They seldom drop to minus thirty degrees Celsius, but minus fifteen is not uncommon in the middle of winter. This clever device is lightweight (0.5kg for a four-cylinder engine) and requires two hours of work to install it. It warms not only the oil, but also the cylinders, providing a homogeneous heat under the cowling. With the help of an insulated engine cover, oil temperature is forty degrees Celsius and the cylinders are lukewarm when it is minus twenty in the hangar. And the battery housed in the engine compartment appreciates it! An engine heater is not cheap, but more efficient and much safer than improvisations like the a cabin warmer on a wooden chair just in front of the exhaust system I have seen elsewhere.
Thus equipped, Echo Romeo can cope with the harshest of winters.
The first thing to keep in mind is that SAR operations in remote and sparsely populated areas can possibly take a while. Then, safe flying in those conditions involves some key aspects: a ‘flight sheet’ (written plan) for every flight, adequate clothing, an emergency beacon and an emergency kit.
Flight sheet: filing a flight plan is not necessary as long as you have written down where you have planned to land, how much endurance you have, how many POB and, most importantly, your ETA. Give this sheet paper to a reliable person who will stay on ground and who will be in charge of calling the SAR services if you do not come back in due time. And please do respect that ETA!
Clothing: being cold in flight is just unpleasant. Being cold on the ground dsiabled aeroplane may become dangerous. So, dress yourself appropriately (in red!) After several attempts, Caroline and I seem to have found the right way: thermal underwear as base layer, ski socks, one (or occasionally two) layers of fleece and a red ski gear on top of that, with warm boots, gloves and a red bonnet. This enables one to be warm without being too bulky. A pair of snowshoes for each person on board may also be useful. Never follow the example of this young lady I saw once on an alpine glacier, descending from a Jodel Mousquetaire in her fur coat and very pretty shoes with pompoms (absolutely unsuitable if she had to reach the valley by foot).
Emergency beacon: if you have no ELT on board (and even if you have one), carry a PLB which will enable you to move away from the plane and be spotted if necessary.
Emergency kit: fill up a box (again coloured red) with some tools, locking wire and tie-raps, silicon tape, strong tape, a can of WD40, a quart of engine oil, an external battery for mobile phone, a snow shovel, a first aid kit, a knife, a little saw (to cut wood and light a fire), a box of matches, firelighters, one emergency blanket for each person, hand and toe warmers, a storm stove and cooking utensils, dehydrated food, energy bars and a candle. It is useless to carry water: just melt the snow. The total weight of this kit is around 6kg.
In addition, the Swedish authorities demand, among other things, that all aircraft flying over ‘mountainous areas’ have contrasting colours. Once again here – you’ve guessed it – red is a good choice. Remember that the famous Max Conrad owed his life to a red jumper he had bought randomly the day before force-landing the all-white Piper he was ferrying from the USA to Europe in Greenland. His jumper was the only non-white thing for many miles around, and that’s what the SAR guys spotted.