Originally Posted by
HazelNuts39
The ice detector that I'm familiar with (Rosemount, IIRC) detects the formation of ice due to freezing of super-cooled liquid water on its unheated ice-collecting element (*). It does not detect ice crystals floating in the atmosphere. Ice crystals do not adhere to unheated surfaces, but may be 'caught' inside a pitot tube.
As I recall, the issue with super-cooled droplets as opposed to ice is that while contact with impurities cause them to freeze near-instantaneously, the operative term is "near" - they can progress backwards along a moving surface some way in that fraction of a second, and that was part of what caused the problems with the ATR back in the '90s because the droplets ended up freezing as ice behind the de-icing boot. If the droplets don't freze until they are behind the ice detector then is is possible that the ice detectors can't detect their presence in a similar manner?
@Lyman - it's right there in the DFDR traces.
The aircraft climbed due to elevator movement and rising pitch attitude (see red line), *not* because of an updraft.