My name is Brad, and I've flown my -6A into (unknown) icing conditions.
Light icing accumulation on the wing (from a different trip than described below)
Coming back from a trip down south several years ago, descending through a layer at about 9,000 to my fuel stop in Sullivan, MO I accumulated what looked like perhaps 3/8" or 1/2" of rime ice on the leading edges of the wing, among other areas. Twisting around, I could see there was a good bit of ice on the horizontal as well, along with some buildup on the windshield.
But I broke out around 9000", the temperature on the ground was reported to be in the 60's, and it was clear below. I had my test cards on my iPad, so I cancelled IFR and re-ran my stall tests.
What I found was the the stall speed increased by approximately 4 knots - not really a big deal. But the nature of the stall changed; it felt more like "tipping over" with a definite nose-down tendency vs. just mushing forward - classic symptom of a tailplane stall. Dropped some flaps and tried it again, same thing only more pronounced.
Kept the descent going and shed all the ice by about 6000' or so.
Lessons learned:
1) The 23000 series airfoil on the airplane didn't seem to be as affected by *this specific instance* of ice buildup as I would have thought. I figured the stall speed would be more dramatically impacted.
2) Climb rate was subjectively only marginally affected; I didn't measure it but had no issues climbing from 7500' to 8500' with the extra load.
3) AoA was not helpful in predicting the stall. I speculate this is because it was a tailplane stall, not a stall of the wing which the AoA indicator is associated with.
4) Flaps had a noticeable impact on the abruptness of the stall, again I speculate because it was a tailplane stall vs. wing.
I had considered the possibility of icing, and mitigated that risk by having an out (warm temperatures on the ground, ceiling well above the freezing level, etc.). Additionally, I engaged pitot heat before entering the undercast to prevent ice buildup vs. waiting until I suspected a problem.
I've encountered light or more severe levels of ice several other times - and have promptly exited icing conditions by climbing, turning, or otherwise leaving ASAP. Controllers have always been very accommodating once they hear the word "ice". Don't be afraid to ask for a change when seeing ice start to accumulate, and don't be afraid to *tell* them what you are doing if they can't/won't help. A non-event in something with turbines and bleed-air anti ice could be catastrophic in a piston single.
I think of it like this: Winning a fight with icing conditions is like winning a gunfight - the only sure fire approach is to be somewhere else.