Originally Posted by
piperboy84
I didn't realize that frost can form in the wings in flight
That is quite a scary statement.
Remember, if it's only just above freezing on the ground it will be below zero at altitude. An hours flying in sub zero temp will cold soak the structure and pick up any moisture as frost.
It doesn't need to be metal either. Years ago I flew a hang glider on a cold New Years day. After a short 30 min flight I landed and noticed frost on the Mylar leading edge.