Page 26 - Dec21T

“A day without sunshine
is like, you know, night.”
– Steve Martin
From the Flight Deck
by Kevin R. Dingman
Snowf lakes
Will pilots have a “flip-flop” winter?
e all have been told that no two snowflakes Winter solstice is the day with the fewest hours of sunlight are alike. But in 1988, Nancy Knight from the during the year. Our shortest day this winter will have 9 hours National Center for Atmosphere Research, using and 13 minutes of daylight. In the Northern Hemisphere,
a microscope, found two that were. Can you imagine her the points on the horizon where the sun rises and sets
in a freezing cold room sorting snowflakes for months? How did she even move from one flake to the next without damaging them? In modern vernacular, snowflake is used to describe a very sensitive person; someone easily hurt or offended by the statements or actions of others; sometimes inclined to flip-flop their position but not inclined to take criticism for doing so. For this story, snowflakes are ice crystals – not sensitive to anything but aircraft anti-icing equipment, liquid deicing fluids, atmospheric conditions and those molding them into snow forts, snowballs and snowmen – sorry, snow people.
For all life on earth, nothing is as fundamental as the length of daylight. The tilt of earth’s axis affects the duration of daylight and plays a major role in our weather. It’s tilted at an angle of 23.44 degrees to the plane of its orbit, and because of this, at certain times during the orbit, it’s dark longer and we get cold weather. For us aviators, it’s a time of the year that produces fast-moving fronts, icing conditions, strong and gusty winds with drifting snow, and it’s like, you know, winter. The term solstice comes from the Latin words sol (sun) and sistere (to stand still) because, during the solstice, the angle between the sun’s rays and the plane of the equator (declination) appears to stand still. In the Northern hemisphere, the winter solstice always occurs around December 21 or 22. This year, it’s on Tuesday, December 21 at 10:59 am EST and marks the official start of winter in the Northern hemisphere and summer in the Southern Hemisphere.
24 • TWIN & TURBINE / December 2021
advances southward each day and the high point across the sky, which occurs at local noon, also moves southward each day. At the winter solstice, the sun’s path has reached its southernmost position. The next day, the path will advance northward. However, a few days before and after the solstice, the change is so slight that the sun’s path seems to stay in the same place or stand still – to “solstice.” The sun is directly overhead at high noon on winter solstice along only one planetary marker: the latitude called the Tropic of Capricorn. Now that we’re up to speed astronomically and understand why it’s so cold and dark outside, onward to its relevance to our operations.
With the exception of the Northeast having a stormy January and a tranquil February, the Farmers’ Almanac (more accurate than an Ouija board, horoscope and some meteorologists) says the rest of the continental United States will see a “flip-flop” winter with larger than normal temperature swings with a near-normal amount of snow. With the extreme weather patterns seen lately that have been attributed to climate change, their forecast seems intuitive. Winter flying can be more work for pilots: snow removal and preheating are added to the preflight list, taxi speeds are slower and low visibilities can be widespread. Temperatures in the North may cause nostrils to momentarily stick closed, and thin layers of snow will create a squeaky noise when we walk. But, compared to the hot, humid days of summer, from the airplane’s anthropomorphic position, it’s ideal – the kind of weather it loves: cold, dry air for the motor to breathe and tightly-packed molecules for the wings to finesse into lift.
Traveling in our airplanes exposes us to wide-ranging temperatures and weather, even without the f lip-f lop forecast. The biggest wintertime changes for us occur during planning and preflight: preheating motors, adding a fuel system icing inhibitor (FSII) like Prist to our jet fuel when needed, using deice fluids, calculating holdover times and selecting alternates. When inflight, we’ll be monitoring fuel