Answer:
Ice that forms on the wing aft of the active part of the deicing boots.
Explanation:
Larger ice droplets are expected to have greater inertia and thus are less likely to be influenced by the flow of air around an aircraft. For this reason, the surface of the aircraft would have larger ice droplets on it. To detect supercooled large droplets, search for ice that can be seen at the back of the active part of the de-icing boots.
