Snow is on my mind. My snow blower has been in daily use for weeks here on the eastern shore of Lake Michigan. My airport, Muskegon County, has recorded more than 90 inches of snowfall so far this winter. That is close to the seasonal average and there are weeks of winter to go.
Flying in the snow is a huge risk for VFR because snow, even moderate snow, cuts visibility to almost nothing. You may as well be inside a cloud as to fly into a snow shower. Unless you’re flying an airplane with automatic landing capability snow reduced visibility is a big problem under IFR, too, because you still have to see to land at the end of the instrument approach.
But most of the hassle of flying in snow is on the ground. The taxiways and runways have to be cleared. With the kind of snow we’ve had this year the snow banks on either side of the taxiways become an issue, especially for low wing airplanes, because the snow piles become higher than the underside of the wing tips.
And then there is the ice that packed snow becomes on pavement. Except for turboprops with their flat pitch “beta” propeller setting it’s impossible to get rid of all of the thrust of an idling engine. Once an airplane starts to slide—with wind gusts often pitching in to add to the fun—we pilots are pretty much along for the ride until the tires find some grip, if they do before you hit the snow bank.
It snows a lot here on the downwind shore of Lake Michigan so my airport is prepared. The maintenance guys have superb equipment and they work long hours. At least one runway is always operational, the taxiways available, and by 7 or so in the morning the T-hangar apron and taxiways are cleared.
But this winter has been so windy clearing the falling snow is not even half the battle because the wind just picks up the snow and moves it back over the pavement. Airports need lots of open space so we don’t have obstructions to avoid and that space gives the wind lots of distance to do its snow moving work. What looks like even a small drift sends the airplane turning toward the drift when one of the main tires hits the drift before the other. Taxiing can be an adventure.
I’ve spent way too much time flying in snow country during the winter but only twice have encountered the absolutely smooth snow cover that destroys all depth perception. It doesn’t happen often, but is a strange and even scary experience on landing.
The first time I encountered the “glassy” snow cover on landing was at Kirksville, Missouri several years ago. I descended out of the clouds into good visibility on the approach to see nothing but white ahead. It was morning, it had snowed overnight, and there was no wind. The snow cover was absolutely uniform and smooth.
The localizer was centered so I knew the was runway straight ahead. I had no way of knowing how deep the snow was because there was no weather reporting on the field and nobody on Unicom. There was not a tire track or windblown ripple on the surface of the snow. The runway is 100 feet wide, and long and I could see some of the edge light stanchions sticking up through the snow. As I descended close to the runway my depth perception evaporated. I didn’t know if I was 10 feet in the air or 10 inches.
I raised the nose, reduced the power a little, and hoped. The airplane settled softly into the snow which turned out to be only about three inches deep. The soft snow cushioned the touchdown but when the wheels actually touched the snow came as a surprise to me.
What I had experienced is the same phenomenon as landing on perfectly smooth glassy water in a floatplane. Our eyes and brain need texture to judge distance. When a surface is perfectly uniform there is no texture and our senses go tilt. The people who design visual displays for simulators learned this many years ago. If the sim shows you a uniform and smooth runway we can’t judge our height. But if there are expansion cracks in the pavement, or a little rough appearance to the surface, we can make decent landings.
The only other time I have experienced the “glassy snow” was landing at Oshkosh on Runway 27 one morning last winter. Again, there was not a single track or tiny drift on the snow, but this time I knew what to expect. I simply held a steady descent rate and nose-up attitude and waited for the wheels to find the surface of the snow.
Being the first to land on perfectly smooth snow is quite an experience, and one I don’t expect to have this winter. It’s blowing more than 30 knots out there again today—and snowing sideways.