Last August I was flying home from Quebec City, passing through the tops of some clouds at 8,000 feet when some sparkling crystals on my OAT probe caught my eye. That’s the first place I look when I suspect ice; but on this summer day it caught me a bit by surprise. The tops of the puffy cumulus clouds were unusually soggy, and a glance at the wing leading edges also revealed some light rime. I asked for 10,000 feet, told the controller why, and the sun quickly eliminated the trace of ice.
Now that we’re getting closer to Halloween, it’s time to be that much more aware of frost on the pumpkin — and on our airplanes. Some points to remember include the preflight. If you don’t have a hangar, or if your airplane was stored outside during an overnight trip, you need to be concerned with frost buildup overnight. Be especially concerned if one wing has southeast exposure, since the rising sun could melt the frost off that wing long before it reaches the other. Reduced lift on takeoff from frost buildup is bad — but asymmetrically reduced lift is even worse.
