B777 Ldg Climb Limit Weight Table

[BMM389EC]

The B777-300 Landing Climb Limit Weight table says one must decrease the weight by 1500kgs if eng and wing anti-ice on.
Then it says"When operating in icing conditions during any part of the flight with forecast landing temperature below 10 C , decrease weight by 19150kgs"
Why the difference? I thought the 1500kgs would allow for the wing and anti ice on? Whats the the story with the 10 c things and then such a big penalty?

[Old Smokey]

The 10°C landing temperature limitation has nought to do with engine bleed deterioration for anti-icing, but to account for ice accumulation on the unheated portion of the airframe after an iceing encounter.

Above 10°C, it is fairly assumed that any accumulated ice will melt before landing.

Regards,

Old Smokey (who has landed with some scary ice accumulations)