Thursday, January 1, 2004
Get The Most Out Of Winter Part 1
With cool temperatures and great visibilities, autumn-to-spring flying requires a different set of rules—and it all starts on the ground
It may come as a surprise to pilots from southern latitudes, but winter flying can be some of the best there is. I have to be kidding, right? After all, isn’t winter the season of blinding blizzards, chillingly cold temperatures and iced asphalt? Aren’t the dark months the time when weather becomes the most miserable and unpredictable of the year? Don’t many pilots who live in northern climes simply lock up their airplanes from December to March and forget about flying altogether?
Sadly, some of the above is true, but that’s only part of the story. As a pilot raised on airplanes in Alaska, I know there’s another side to the winter flying question, one that too many aviators ignore in deference to the season’s almost overwhelmingly negative image. Winter does have some good news for pilots, and if you’re adventurous of spirit and willing to do some preparation, it can be the best time of year to fly.
As every pilot knows, colder temperatures provide denser air for more efficient engine operation. In fact, when the thermometer really drops, even a normally aspirated engine can develop so much more than sea-level standard power, you may need to back off the throttle on takeoff. Similarly, the thick, grabby air of winter makes airfoils happier. The wing and tail provide better lift, takeoff distances are shorter and climb is enhanced by cold air.
Cold air holds less water vapor, so moisture normally condenses as readily visible clouds rather than lingering in the air as does the heat haze of summer. Partially for that reason, winter flying often is smoother than in summer. Without a high, hot sun to heat the ground, convective activity is reduced and skies are calmer. Similarly, inversions are less common than in summer. The high sky is liable to be cooler and more comfortable than at any other time of year.
If you happen to live in the upper two-thirds of the U.S. or anywhere in Canada, winter is a major consideration, especially when it comes to that vital component, the battery. One of your main operational concerns in winter is conserving electrons, since battery power is at a premium in cold temperatures. For that reason, anything that can improve starting efficiency can make life easier when the thermometer begins to take a dive.
To that end, you should make a realistic assessment of battery condition and replace it if it’s not in top shape. Check the specific gravity (1.265 is a full charge), top up the electrolyte level if necessary with distilled water and clean the terminals of any acid accumulation. Similarly, this is an excellent time to check battery cables, especially on those airplanes with long cables that store the battery under the baggage compartment or in the tail for CG reasons.
Engine tune is important, too, especially when it comes to starting efficiency. Have mag timing and plug condition checked by a mechanic, not only for general engine health, but to assure that winter starts will demand minimum cranking. Heavyweight oil can take on the consistency of taffy in cold temperatures and drag down a battery in a hurry, so plan to switch to a lighter grade of oil if you’re flying into sub-zero conditions.
Have heat-exchanger-style heaters (which draw hot air from radiation off the exhaust manifold) inspected for leaks that might allow carbon monoxide to infiltrate heater air, and check fuel-fed ignition heaters for leaks that might pose a fire hazard. Equally important, make certain the airplane’s heater works reliably and well. A heater failure in severe conditions can represent a very real problem.
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