What decides if additional GA thrust required

[mfclearner]

Thanks

Thanks alot very well explained. So one has to use ''Landing Climb Limit Weight'' table from performance dispatch section. But again my question would be... won't dispatch take into account landing climb limit weight?
Or this is just in case there is sudden increase of OAT at landing airport? Or your Non Normal is forcing you at airfield which is having high PA and/or OAT