Sunday, February 1, 2004
Get The Most Out Of Winter Part 2
Last month, we took a look at how much cold-weather flying depends on groundwork preparation. In this issue, we’ll explore how to safely and effectively maximize wintertime flight once you’re airborne.
|Read the owner’s manuals for several aircraft, and you’ll discover cold-weather starts are different for each engine, but there are some fairly universal rules to follow during cold start attempts. Some pilots refuse to move prop blades under any circumstances, but I always pull them through several times to break any possible hydraulic lock. Fuel is reluctant to vaporize in cold weather, and you’ll need to prime the engine(s) more than normal if you expect to start on the first or second try, an important consideration when two tries may be all you’ll get. |
Assuming the weather between departure and destination is less dramatic (usually the case), your biggest challenge in winter may come when it’s time to put the airplane back on the ground. The temperature at typical cruising altitudes may be well below -10 degrees C, so you’re liable to increase your risk of icing as you descend into warmer air below. If you fly a fairly fast airplane, aerodynamic heating at high cruise speeds may help offset some airframe icing. Slow the airplane to approach speed, and you’ll lose that heating effect. Be especially wary if you’re assigned an altitude in the middle of the ice or a holding pattern that flies you through an area of icing. Don’t be shy about telling the controller you prefer ice in your Gatorade rather than on your airplane.
Letdowns through a layer of ice can present problems, too. In those instances when I have considerable altitude to lose and must descend through a possibly ice-laden overcast, I’ll often stay higher longer, then drop through at a relatively high descent rate. To avoid shock-cooling the engine, I leave power at a tolerable level, but configure the airplane for the approach early. That way, I can penetrate the ice at maximum vertical velocity (1,000 fpm or more), but minimize forward speed to reduce ice buildup. I like to arrest that high descent rate well above my target altitude, but I always keep in mind that, at this stage of the flight, any ice I accumulate probably will stay with me through the landing.
Speaking of landings, you may need to be more attentive during winter than in summer. Winds sometimes are stronger, snow and ice on the runway can be significant considerations, and falling snow during the approach can render landing lights worse than useless. Stay off the brakes after touchdown if there’s any question of ice, and beware of “black ice,” a phenomenon of icing on asphalt that may be nearly invisible. If you must use the brakes because of a short runway, do so very warily, applying them gently and evenly to avoid asymmetric braking across patches of bare asphalt. To paraphrase one of Mother’s old sayings, Take all the runway you want, but don’t use more than you have.
Just as with landing on a dry runway, do your braking in a straight line. Bring the airplane practically to a full stop pointed straight ahead before even considering a turn off the active. Don’t try to make a high-speed turnoff to accommodate the controller if you sense even a hint of directional problems. An icy runway isn’t the place to practice short-field approaches, but don’t wait too long to apply the binders. Braking action at the opposite end of the runway may be especially poor where aircraft residues such as tire rubber, fuel and hydraulic fluid accumulate.
Finally, rethink your summertime attitude regarding alternates in winter. Weather moves faster in the late months. What was clear and 20 two hours ago at your destination may be down to 200 and a half in another hour when you arrive. It’s a mistake to assume early-morning fog at your destination will dissipate as quickly as it might in summer, too. The sun is farther south, arcs lower on the horizon and has to shine diagonally through more atmosphere, so less heat and light reach the ground to burn off the clouds. Shorter hours of daylight also contribute less heating.
If these warnings lead you to believe winter flying isn’t worth it, you might want to reconsider. Winter can be a spectacular time to fly. True, you need to exercise more cautious weather judgment, and there are some different operational considerations to flying when the thermometer is low, but with a little care, winter can be one of the most rewarding times of year to fly.
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