Page 15 - Dec15

mean dealing with tomorrow’s or yesterday’s weather, as well as today’s.The good weather days are the ones that are cold and clear, miserably frigid under domes of high pressure. Warmer weather brings cloud layers and the threat of precipitation. Most of the time, you’ll find it relatively easy to top the lower layers of cloud, since the clear air is waiting no higher than the low teens. The bad news is that, if there’s any moisture about, you won’t want to linger during the climbout. Icing is going to be found at some level in those clouds, maybe even on the ground under them. Depart without delay, with everything turned on to ward off ice, and expedite your ascents and descents. Do not fool around with “just a little ice”, and don’t count on it sublimating away in the clear, particularly if the sun angle is low or non-existent.Winter precipitation is much more schedule- threatening than summer showers. Light rain is hardly cause for concern, only dropping visibility to a couple of miles unless the air becomes saturated. Light snow, on the other hand, can immediately result in a quarter-mile of whiteout visibility, and it only takes a cloud layer as thick as a handkerchief, it seems, to generate significant snow. Down low, a snow-covered landscape blends into an indistinct cloud base with dangling tentacles of snow. Reported ground visibility might be enchantinglyoptimistic, compared to the forward flight visibility seen from the cockpit. Sure, you can always see the ground straight underneath the airplane in snow, as long as you’re clear of cloud, but as the intensity of falling snow picks up that circle of visibility shrinks.When flying near significant bodies of water, be cognizant of the lake effect snowfall on the downwind side of the moisture source. As an otherwise-mild change in air mass moves across the water, it picks up moisture it can’t hold and readily dumps it the form of airport- closing amounts of snow to the south and east. Chose an alternate on the dry side of the water or far to the south.Circling approaches are particularly risky when snow is falling; there’s nothing much in the way of visual reference to maintain orientation. All of the cockpit aids on the panel need to be supplemented with old- fashioned caution when you’re groping for an airport that passed by under the side window.It’s quite common to encounter temperature inversions during the cold season. Cold air pools at ground level overnight, leaving the previous afternoon’s relatively-warm air floating along a few thousand feet AGL. Pollutants are trapped in the cold layer and cannot rise through the cap of warm air, reducing visibility. When moisture-laden warm air moves over the top of the stubborn cold air, raindrops falling into the sub-DECEMBER 2015TWIN & TURBINE • 13Covington Aircraft Engines Half Page 4/C Ad