Originally Posted by
Intruder
1. Wing anti-ice does not work with slats extended.
This is incorrect, on some aircraft there is no wing anti-ice for extended leading edge devices such as the 747 while others like the 727 and 737 range from mostly heated to partially heated while extended. Whether the heated device have as effective anti-icing capabilities when extended, I am not sure but would not be surprised if it is less effective.