ATR's don't like icing with flaps retracted!
Just a couple months ago an ATR-72 and my humble DHC-8-102 were climbing for FL240, in moderate icing for just a little over 20 min. We still had a stable climb rate right up to the top, while the ATR ended up descending because they could not maintain altitude at 17,000. Much different wing between the two (same basic weight as talked with the crew an hour later) resulted in different characteristics. As a crew we discussed that the second we saw a trend towards a level (+200 fpm or less) or negative climb rate, we were going to descend for warmer air, and we had already changed our heading to try and get out of the icing. Prudent discussions anytime you find the white crap on the plane.
As it is, no icing is good icing and many competent (and not so competent) pilots have not reached home base because of staying in icing conditions.
NASA has a great icing training series found here:
Aircraft Icing Training - Courses
It's a great series for those of you who don't encounter icing on a regular basis, and a great refresher for those of us who do.