Ice Country

Mt Jefferson with Three Finger Jack in the Foreground taken 7:30 am March 23,2007 Friday


Ice is a strange thing. Jets don't have a problem with it, they go so fast that the ice doesn't have a chance to stick. They also punch up through the clouds fast. They fly high where there are no clouds and thus no moisture. There must be moisture for there to be ice. Thus clouds and freezing temperatures are a recipe for ice. Ice on airplane wings can do strange things. However certain types of ice is worse than other ice. The most common form of ice is "rime" ice. Rime ice is small even granules that form evenly over the front or leading edges of the wings and other parts of the plane. It is not uncommon to pick up a little rime ice either ascending above or descending below the clouds. Clear ice is entirely different. Clear ice is like the ice you see on your windshields, sometimes when you get freezing rain. It can form streaks. That ice is very dangerous. There also is what is called mixed ice. Mixed ice is a combination of rime and clear ice- it can get pretty ragged. All ice is dangerous, but the last two can accumulate quite fast. Since an airplane travels so fast through frozen moisture there is a potential to accumulate ice. What ice does is deform the wings and if care is not taken to get out, it can cause the plane to stall by the wings not being able to generate lift. The weight isn't the problem, it is the deformation of the wings that causes the problem.

I will never fly if there is clear ice forecast, or an ice storm. They are quite rare but that is a flat rule. If I encounter ice it usually quite easy to determine the rate of accumulation and also to fly at an altitude where the ice does not accumulate or fly above or below the clouds. Remember moisture or clouds are necessary for ice. Having a turbocharged engine allows me to climb high above the clouds ,and at around 1000 feet per minute, which for a small plane is pretty fast.

One time coming back from Klamath Falls I climbed up to over 19,000 feet to get out of the clouds. Usually I never have to climb that high. Last Monday afternoon coming back from Tri Cities I encountered light rime ice. I always report ice to the air traffic controllers I am talking to. It is mandatory. They want to know the outside air temperature, rate of accumulation light, moderate, or heavy and type of ice. They are very willing to facilitate a routing or altitude to get out of the ice. It is always a good feeling when you descend, when you get close to 32 degrees. The ice on the windshield starts to slide off like frosting off of a cake, then peels off the wings. Sometimes you will hear chunks hit parts of the plane as it flies off.