Making the safe decision (AKA "I hate AIRMET ZULU")

: This weekend in WI was a perfect case of airmets galore, but good planning
: wouldn't have prevented flying due to ice. Overcast at 2700, clear above
: 3000.(4000 MSL) light to moderate rime ICIP airmet blanketing the entire
: state. VFR both south and north of us, surface temps between 40 and 45F.
: Freezing level 4000 MSL north sloping to 6000 MSL south. ADDS was
: predicting a 80-90% chance of icing at 6000, nothing at 3000, and nothing at
: 9000. The "go" decision could be made because the clouds at 2700-3000 AGL
: were below the freezing level and it was clear above, so the airmet didn't
: have any weather that it applied to. Be careful when using ADDS that you
: remember ceilings are AGL, icing predictions are MSL. So, we could have
: taken off, climbed through the ceiling into clear air.

: What if we come upon a layer at 6000 where ADDS said 80-90% chance of ice?

: What are our outs?
: 1) Climb above it, ADDS predicted 0% at 9000, climb is always my first
: choice. you can climb before you accumulate ice, you can always go down.

: 2) descend below it and continue, MEA is 3000 MSL

: 3) descend through it and land

: 4) turn around and fly back into clear weather

: 5) turn 90 degrees to the system and fly around it, this requires knowledge
: of the area of coverage and conditions surrounding it, plus additional fuel.

6) Stay VFR at 2500 AGL? If it's overcast at 2700, staying out of the iced-up soup
altogether seems like a good plan as well. I'd rather be at 1500 AGL in VMC than
slogging through the soup waiting for ice to start accumulating and have to choose an
"out"

-Cory


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* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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