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Hello again from my world of flying! Quite a bit has happened since the last
update. I got my CFII after taking my time to get comfortable
instructing, learn the local area approaches and getting some actual instrument
time. The checkride went very well and I have been lucky enough
to currently be instructing a few instrument students. The weather has been
great for instrument flying with relatively high freezing levels and a few
weeks ago I doubled my actual instrument time in just one week. Oregon is
a great place to build instrument experience and confidence as well as
judgment regarding the go- no go decision. I have learned some valuable
lessons, in particular about icing, which is the focus of this months
article.
I had my first encounter with icing, which luckily I was able to get out of,
however the fact that I allowed myself to get into that situation shook me
up and really made me rethink my go-no go decision. Legally I had covered
myself. No known icing (no pireps), the forecasted freezing level was at
7000 ft, and temperature at 6000ft was forecasted at plus 2 degrees C. I
got two briefings and had current information on DUAT. What I neglected to
take into account was that the MEA on my route of flight was 6000 (the
altitude which I filed and still below the freezing level) and although on a
westerly heading (even thousands) ATC in the area prefers to send departures
up to 7,000. I took off with my student and one additional passenger, and
got sent up to 7,000 as soon as I contacted approach. I studied the
temperature probe and was relieved to see it still above freezing. We were
about 500 feet above the layer and it was clear skies above. It was my first
instrument x-country with a student and it was a beautiful flight to the
coast. I relaxed a bit and took in the amazing sea of clouds below us and
blue skies above. That's when things started turning against us. The tops
started forming from a nice stratus layer to stratocumulus as we approached
the coast range. The clouds marched higher and as we prepared to enter the
first top I advised my student to focus on the attitude indicator and
increase his scan rate.
The ice formed at an incredible rate. Large water droplets hit the
windshield, ran for about 2-3 inches and then froze solid. I looked over at
the temperature probe, which was now suddenly below freezing. We broke out
of the first tops and looked ahead at even higher dark gray cumulus clouds.
The first thing in my head was the numerous articles about not climbing out
of freezing in GA aircraft because of the slow climb rates. We were already
heavy with 3 passengers and full fuel, were picking up ice and all I could
think about was ' Plus two degrees C at six'. I called approach, told them
we had icing and asked for lower. They responded and gave me 6,000ft. We
descended nervously down to 6,000 and almost instantly began to accumulate
clear ice. The windshield was solid ice and the tire and strut were
covered. I knew I had to get out of there, but as I called approach, I was
thinking 'how did I let myself get into this, my student and passenger
trusted me, what did I do wrong?' I quickly pushed those thoughts out of my
head and put all my efforts into the task at hand: getting out of this
situation, flying the plane and going home safe. I called and advised
control of our situation and started back out of the icing conditions. I
received a clearance to head back the opposite direction at 6,000 and at
this point I was at nearly full power to maintain altitude and airspeed. I
knew we had to go back through what we just came out of and I frantically
searched with my student for a MOCA (lower altitude), unfortunately would
not hit one for another 14 NM. We were over the mountains, accumulating
clear ice, with no way to go lower. I was teaching an instrument ground
school at the time and had just covered ATC vectors and obstruction
clearance. I knew we were on radar so I quickly called approach, updated
our situation and requested Minimum Vectoring Altitude. They came back and
luckily go us down to 4,000 within a few minutes and I watched with great
relief as the ice chunks started breaking off. As we touched down safely
back home, I started second guessing myself, 'should I have climbed above
the layer' or 'did I just violate every FAR in the book?' or 'how was I
stupid enough to put other peoples lives at risk?' The only thing I knew
for sure was that I was going to make sure that I figured out how to avoid
putting my passengers or myself in that kind of situation again.
Since that time, I have spent a lot of time studying icing conditions,
avoidance techniques and conditions that have high risks of encountering
structural icing. According to AC 00-6A Aviation Weather, there is a
greatly increased chance of icing over mountain ranges as the moisture is
forced upslope and forms super cooled water droplets. As well, the two
conditions necessary for ice to form are visible moisture and the
temperature at the point where the moisture strikes the airframe to be 0
degrees C or colder. Aerodynamic cooling can lower the temperature of an
airfoil to 0 even though the ambient temperature is a few degrees warmer.
Severe icing is more likely near the tops of the clouds due to increased
moisture levels.
The bottom line is always have an 'Out'. Foolishly I didn't have one. A
MEA of 6000ft and forecasted freezing of 7,000ft is not a sufficient buffer.
I learned a valuable lesson that day, it is not enough to simply use the
forecasted weather or freezing levels, we must learn to anticipate the
situations and conditions which will lead dangerous situations and act
accordingly. A factor was my failure to see the big weather picture and my
lack of 'local knowledge'. Luckily I am at a school were everyone feels
comfortable to admit their mistakes, determine the factors involved and
learn from them. I made deliberate and careful decisions that I thought
were best and luckily turned out OK but it easily could have gone the other
way. By far the most prudent decision would to have not put my passengers
or myself in that kind of situation without a planned escape route.
At the end of the day, icing is where you find it, and if you do, you need
a
way out of it ahead of time.
Fly safe.
Jon Reed
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