Originally Posted by DozyW
If the droplets don't freeze until they are behind the ice detector then is is possible that the ice detectors can't detect their presence in a similar manner?
The referenced paper offers a number of arguments for the prevailing opinion that the high altitude power-loss events, and perhaps also the pitot problems, are caused by convective clouds containing a very high density of tiny ice crystals. The point I was making in my post is that the well-known
Rosemount Icing Detector does not detect ice particles, since it is designed to detect super-cooled liquid water droplets. BEA says that the presence of liquid water at -40° C is unlikely, and must necessarily have been limited to small quantities. If there was liquid water in sufficient quantity to cause icing problems, I think it is highly improbable that it would have been missed by the ice detector(s). If your scenario was valid, how could they ever detect ice?
I don't think that you are correctly describing the cause of the ATR accident at Roselawn. IIRC, the theory is that the airplane encountered unusually large super-cooled droplets at relatively low altitude. Due to the large droplet size, the area of ice accretion extended beyond the deicing boots. While the ice on the boots is periodically shed by inflating the boots, the ice aft of the boots remained and formed a ridge on the upper surface of the wing just aft of the boots. This is just from memory, feel free to correct me. I don't see any connection to the functioning of an ice detector.