And some smart corporate operators, which shall remain unnamed
, have perfected the good idea from Braathens. The black painted area is extended to cover approx 6" of the unheated outboard leading edge slat, as well as the adjoining heated slat. Very easy to detect if any ice accumulation remains on the leading edge after WAI application.
Any windshield frame ice or wiper nut accumulation = wing ice. More so on the NG than CL, due to the smaller radius leading edge wing design.