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Feature Article

Matt Debsky, Aircraft Owner WVFC tdebber@alum.mit.edu

Icing Lesson 

In the October 2011 WVFC Newsletter, I wrote about my first trip from the Bay Area to Corvallis, Oregon.  That trip convinced me that if I wanted to make travel via a small plane safe and somewhat predictable, I needed to get my instrument rating.  Less than a year after that trip, I had my freshly minted instrument rating in hand.  Eager to put the hard-won rating to work, I planned a trip with two friends to Portland, Oregon.  I don't especially recall the trip to Portland, though my logbook shows 0.2 hours of actual, so I must have been in the clouds at some point.  Already the rating was paying off!

After a weekend in Portland visiting bookstores, markets, and small breweries, my friends and I piled back into the Piper Archer for our return to the Bay Area.  My recollection of the day is one of light rain and layered clouds; the online METAR archive backs this up (http://vortex.plymouth.edu/sa_parse-u.html).  The freezing level was between 6,500 and 7,500 feet.  Given the layered clouds, I wasn't planning to spend a lot of time in them and was not concerned with icing.  We took off out of the Portland area and headed south.  Before reaching Eugene, roughly in the center of the state, we were spending considerable time in the clouds.  During the periods we weren't in instrument conditions, I interrupted my scan to see ice forming on the leading edge of the wings.  I informed the controller of this, and could tell from the tone of his voice that he thought it was a bigger problem than I did.  He quickly gave us a new routing and assigned a lower altitude.  Descending back below the freezing level and out of the clouds, the ice quickly melted.

In order for us to continue on our path to California over the Siskiyou Mountains, we would need to climb to 10,000 feet.  This would mean entering the clouds again, along with their potential icing. Working with the controller, I elected to begin a climb well north of the mountains.  That way, if the ice returned we would be able to descend to warmer, clearer air instead of being forced into the mountains.  Fortunately, as we climbed back into the clouds the Archer continued her steady ascent without any additional ice and we popped into sunlight for our trip across the border.

I reviewed the flight after making it back to the Bay Area.  I mentioned that the controller sounded more concerned about the ice than I was.  That was because I didn't have an appreciation for how quickly ice accumulation can become a big problem.  The Archer is not an especially powerful aircraft.  Ice could have accumulated quickly enough that the weight and aerodynamic dirtying effects could have caused the plane to be unable to maintain altitude.  Working to get out of the icing conditions as quickly as possible gave us options, including landing at an airport short of the mountains to wait for more favorable weather conditions or choosing a route with fewer clouds.  Following that flight, I have paid more attention to the freezing level, even if I believed I wouldn't be in the presence of visible moisture.  I also made sure that I had a Plan B and Plan C ready if I did happen upon icing conditions.  Additionally, I review the Aviation Weather Center Icing products (http://www.aviationweather.gov/adds/icing/) to help determine the icing potential at different altitudes.  My first icing encounter taught me to pay more attention to icing potential and freezing levels, and reinforced again the importance of constantly evaluating en route conditions and alternative plans.

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