Hi folks
Judging by the altitude of the aircraft it is more likely this icing has been caused by the aeroplane passing through moist air with cold soaked fuel tanks.
The fuel (and therefore the surface of the wing) would accumulate ice if it came in contact with any moisture in the atmosphere.
The ice appears to cover the area of the fuel tanks (that is, non at the wingtips).
Usually this melts prior to landing, but not always. I've arrived on the ground in Spain, for example, with the upper surfaces of the wings having ice still evident. This melts in the heat on the ground during turnaround, however there would be no chance of departing if any ice remained.
I should hope the cabin crew would point icing like this out as if it did remain on the wings prior to landing then there would be performance issues.
Good CRM is to be commended and I hope all pilots would appreciate a word from the cabin about this or any other suspected problem.
KR
FOK
