Thanks gents ! And thanks John, you' re the best old fat balding Irish man on the net.
Off course, I forgot to put the type. Well, interstingly enough, the penalties on icy runway are similar to the 777. I guess they all follow similar algorythms.
It looks like someone can crunch some OPT figures for me so the problem should be resolved soon. I just need a gross figure of available payload.
I will let you know if the project goes ahead.
Thanks again guys,