TurbineBlade
Doc had it about right, however I would add that the safety concern is associated with penetration of a storm front ala the Easyjet thread above.
It isn't so much freezing weather as it is the ingestion of mixed precipitation in a severe storm front (mixed rain and hail).
In order to keep the engines running stable you need all the improvements he cites.
oops I forgot about low flight idle affecting fan blade icing on approach. Not a biggie but the increase in vibration tend to bother some pilots and Feds
However, as always the Boeing FCOM should supercede any
free advice that you get on this forum
